Srinivas

Reviewing AP Inter 2nd Year Zoology Study Material Chapter 2 Reproductive Health Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Zoology 2nd Lesson Reproductive Health Questions and Answers

IV. Very Short Answer Questions

Question 1.
What in your view, are the reasons for population explosion, especially in India?
Answer:

1. Significant reduction in the death rate.
2. Decrease in Maternal Mortality Rate (MMR).
3. Reduction in Infant Mortality Rate (IMR).
4. Increase in the number of people belonging to the reproductive age group.

Question 2.
What is amniocentesis? Name any two disorders that can be detected through amniocentesis.
Answer:
1. Amniocentesis is a prenatal diagnostic technique used to identify genetic abnormalities in an unborn child.
2. Disorders that can be detected include:

• Down syndrome
• Edward’s syndrome
• Tumer’s syndrome

3. In this procedure, a sample of amniotic fluid is collected, and foetal cells are examined.
4. However, misuse of this method for determining the sex of the foetus has led to legal restrictions.

Question 3.
List out the contraceptive methods available to the couples.
Answer:

1. Periodic abstinence
2. Condoms
3. Vasectomy (male sterilization)
4. Tubectomy (female sterilization)
5. Coitus interruptus (withdrawal method)

Question 4.
Mention the advantage of Lactational Amenorrhea. (APMAY-22)(APMAR.-19,24)
Answer:
Advantages of Lactational Amenorrhea (Breastfeeding Method):

1. During the period of exclusive breastfeeding, the likelihood of conception is extremely low.
2. Breastfed infants receive enhanced immunity and protection against allergic conditions.

Question 5.
List the different types of Intrauterine Devices (IUDs) used to avoid pregnancy.
Answer:
The various categories of Intrauterine Devices (IUDs) are:

1. Non-medicated IUDs Example: Lippes Loop
2. Copper-releasing IUDs Examples: Cu-T (Copper-T), Cu-7, Multiload 375
3. Hormone-releasing IUDs Examples: Progestasert, LNG-20

Question 6.
Mention the mode of action of oral contraceptive pills (daily pills) in preventing pregnancy.
Answer:

1. Oral contraceptive pills mainly prevent pregnancy by suppressing ovulation.
2. They also increase the thickness of cervical mucus, thereby restricting sperm entry into the uterus, and alter the endometrium, making it unfavorable for implantation.

Question 7.
What measures should one take to prevent sexually transmitted diseases (STDs)? (AP MAR-17, 23)
Answer:
Measures to Prevent STDs:

1. Avoid sexual contact with unknown individuals or multiple partners.
2. Use condoms consistently during sexual intercourse.
3. Seek medical consultation for early diagnosis of STDs.
4. Complete the prescribed treatment if an infection is detected.

8. What are the reasons for infertility in human beings?
Answer:

1. Infertility may result from physical abnormalities, hormonal imbalances, infections or diseases i (including STIs), and genetic disorders.
2. It may also arise due to a low sperm count or other male reproductive problems.

V. Short Answer Questions 

Question 1.
Why is the introduction of sex education in schools is necessary?
Answer:

1. Sex education is important because adolescents experience many physical and emotional changes and are naturally curious about reproductive processes.
2. Accurate knowledge about reproductive organs, adolescence, bodily changes, and safe hygienic practices helps students understand these developments properly.
3. Awareness about sexually transmitted diseases enables students to recognize the consequences of unsafe sexual behavior.
4. Therefore, school students should receive scientifically correct information regarding sex and reproductive health.

Question 2.
Describe the following contraceptive methods.
(a) Natural Methods
(b) Surgical Methods
Answer:
(a) Natural Methods of Contraception: Natural methods prevent pregnancy by avoiding the meeting of sperm and ovum.

1. Periodic Abstinence: The couple refrains from sexual intercourse during the fertile period (usually from the 10th to 17th day of the menstrual cycle), thereby reducing the chances of fertilization.
2. Withdrawal or Coitus Interruptus: The male partner withdraws the penis before ejaculation, preventing sperm from entering the female reproductive tract.

(b) Surgical Methods of Contraception: These methods are permanent sterilization procedures.

1. Vasectomy: A small incision is made on both sides of the scrotum, and a portion of the vas deferens is cut and tied. This prevents sperm from reaching the seminal fluid, making the semen free of sperms.
2. Tubectomy: Small incisions are made on both sides of the lower abdomen. A section of each fallopian tube is cut and tied, preventing the ovum from reaching the site of fertilization and thereby preventing pregnancy.

Question 3.
Which barrier methods are effectively useful for newly married couples to avoid conception?
Answer:
Barrier methods prevent fertilization by physically blocking the meeting of sperm and ovum.

1. Condoms (Male and Female): These are thin latex or rubber coverings used over the penis or inside the female reproductive tract. They are easily available, disposable, provide privacy, and also offer protection against STIs and AIDS.
2. Diaphragms, Cervical Caps, and Vaults: These devices are inserted into the female reproductive tract to cover the cervix and prevent sperm entry. They can be reused and are effective contraceptive barriers.
3. Spermicidal Agents: Creams, jellies, and foams are used along with barrier devices to destroy or immobilize sperms, thereby increasing contraceptive effectiveness. These methods are safe, reversible, user-friendly, and have very few side effects, making them suitable for newly married couples.

Question 4.
Write short notes on any two of the following.
(a) MTP (Medical Termination of Pregnancy)
(b) RTI (Reproductive Tract Infections)
(c) SAHELI
Answer:
(a) MTP (Medical Termination of Pregnancy): MTP refers to the deliberate termination of pregnancy before full-term development using medical or surgical procedures.

• It is performed in cases of unwanted pregnancy, contraceptive failure, or when pregnancy poses a risk to the mother’s health.
• It is considered safer when carried out during the early stages of pregnancy.
• Proper medical supervision is essential to avoid complications.

RTIs are infections affecting the reproductive organs and may be caused by bacteria, viruses, or other microorganisms.

• They may spread through sexual contact (STIs) or result from poor hygiene.
• Common symptoms include pain, abnormal discharge, itching, and infertility if untreated.
• Early diagnosis and proper treatment help prevent complications.

SAHELT is an oral contraceptive pill developed in India.

• It is a non-steroidal, once-a-week pill that is convenient to use.
• It produces fewer side effects when compared to many hormonal contraceptive pills.
• It is widely used as a method of family planning and birth control.

Question 5.
Write short notes on any two of the following, suggesting some methods that can help infertile couples to have children.
(a) IVF (In Vitro Fertilization)
(b) GIFT (Gamete Intra Fallopian Transfer)
(c) ICSI (Intra-Cytoplasmic Sperm Injection)
Answer:
(a) IVF-In Vitro Fertilization :

• Fertilization of the ovum takes place outside the body under laboratory conditions.
• The developing embryo is cultured up to the early stage and then transferred into the uterus.
• This technique is commonly known as the test-tube baby technique.
• The sperm and ovum may be obtained either from the couple themselves or from donors.
• The embryo may be implanted in the biological mother or a surrogate mother.

(b) GIFT (Gamete Intra Fallopian Transfer):

• GIFT is an Assisted Reproductive Technology (ART) used to help infertile couples achieve pregnancy.
• In this method, an ovum (egg) collected from a donor is transferred into the fallopian tube of another female. Fertilization occurs naturally inside the body (in vivo).
• It is useful for women who cannot produce ova but possess normal fallopian tubes and a healthy uterus capable of supporting embryo development.

(c) ICSI (Intra-Cytoplasmic Sperm Injection):

• ICSI is a specialized ART technique in which a single sperm is directly injected into the ovum to facilitate fertilization.
• This method is especially useful in cases of very low sperm count or poor sperm quality.
• The resulting embryo is later transferred into the uterus for further development.

I. Multiple Choice Questions

Question 1.
Amniocentesis is used to detect genetic diseases like.
1) Hepatitis B
2) HIV
3) Haemophilia
4) Syphilis
Answer:
3) Haemophilia

Question 2.
Identify the Intrauterine device (IUD).
1) Diaphragms
2) Lippes Loop
3) Cervical Caps
4) Condom
Answer:
2) Lippes Loop

Question 3.
The sterilization procedure in the male is called.
1) Vasectomy
2) Tubectomy
3) Periodic Abstinence
4) MTP
Answer:
1) Vasectomy

Question 4.
The Transfer of the Zygote or early embryo (with upto 8 blastomeres) into the Fallopian Tube is called.
1. GIFT
2) ICSI
3) ZIFT
4) IUI
Answer:
3) ZIFT

Question 5.
In vitro fertilization (IVF), followed by the transfer of embryo into the female genital tract, is called.
1. IUI
2) Test Tube baby
3) GIFT
4) IVI
Answer:
3) GIFT

Question 6.
What are the major tasks of “Reproductive and Child Health Care (RCH) programmes”?
a) Creating awareness among people about various reproduction-related aspects,
b) Providing facilities regarding reproductive and child health care;
c) Support for building up a reproductively healthy society,
d) Encouraging population explosion
1. a,b only
2) c,d only
3) a,b,c only
4) a,c,d only
Answer:
3) a,b,c only

Question 7.
Which of the following statements is correct?
1. Abortions could happen spontaneously too.
2. Infertility is defined as the inability to produce a viable offspring and is always due to Abnormalities/ defects in the female partner.
3. Completely lactation could help as a barrier method of Contraception.
4. Tubectomy prevents transportation of gametes in males.
Answer:
3. Completely lactation could help as a barrier method of Contraception.

II. Fill in the Blanks

1. Genetic disorders like Down syndrome, Haemophilia, sickle cell anaemia are detected by method.
Answer:
Amniocentesis

2. Central Drug Research Institute (CDRI) is located in ……………………….. .
Answer:
Lucknow

3. The Terminal surgical method to pregnancy is called ……………………… .
Answer:
Sterilization

4. In India, the medical termination of pregnancy (MTP) is legalized in the year ……………………… .
Answer:
1971

5. In …………………….. technique, semen collected from the husband or healthy donor is artificially introduced into the vagina or into the uterus.
Answer:
Intrauterine insemination

III. One Word Answer Questions

Question 1.
Name the new oral contraceptive pill for the females developed by Central Drug Research Institute.
Answer:
SAHELI

Question 2.
Which age group of persons are more vulnerable to the reproductive tract infections and venereal diseases (VDs)?
Answer:
15 to 24 Years.

Question 3.
What are the commonly known special techniques used to help infertile couples to have children?
Answer:
Assisted Reproductive Technologies (ART).

Question 4.
Name the method in which a sperm is directly injected into the ovum.
Answer:
Intra Cytoplasmic Sperm injection.

Question 5.
In which year was a “family planning” program initiated in India?
Answer:
1951.

Objective Questions

Question 1.
Which of the following is an example of an IUD?
1. Copper-T
2. Condom
3. Vasectomy
4. Pill
Answer:
1. Copper-T

Question 2.
Which substances are present in contraceptive pills?
1. Progesterone and estrogen
2. Spermicidal salts
3. Chemicals causing automatic abortion
4. Chemicals that prevent fertilization of ovum
Answer:
1. Progesterone and estrogen

Question 3.
What does the abbreviation MTP stand for?
1. Multi trade practices
2. Malthusian theory on populations
3. Multiple temporary frequency
4. Medical termination of pregnancy
Answer:
4. Medical termination of pregnancy

Question 4.
Tubectomy is mainly performed to prevent
1. Coitus
2. Eggs formation
3. Fertilization
4. Embryonic development
Answer:
3. Fertilization

Question 5.
Which hormone is an important component of oral contraceptive pills?
1. Thyroxine
2. LH
3. Progesterone
4. GH
Answer:
3. Progesterone

Question 6.
Tubectomy, as a method of population control, is carried out on
1. Both males and females
2. Males only
3. Females only
4. Only pregnant women
Answer:
3. Females only

Question 7.
Which of the following is a commonly adopted method of sterilization?
1. IUCD
2. Diaphragm
3. Tubectomy
4. Loop
Answer:
3. Tubectomy

Question 8.
Which mechanical barrier is commonly used for birth control?
1. Copper-T
2. Diaphragm
3. Loop
4. Dalcon shield
Answer:
2. Diaphragm

Question 9.
Which statement correctly describes surrogacy?
1. Surrogate mother is biological mother for the baby
2. The baby will have two biological fathers
3. A woman provides her uterus for the development of someone else’s embryo
4. None
Answer:
3. A woman provides her uterus for the development of some other’s embryo

Question 10.
Which statement about a test tube baby is correct?
1. Fertilization inside female genital tract and growth in test tube
2. Rearing of prematurely bom baby in incubator
3. Fertilization outside and gestation inside the womb of mother
4. Both fertilization and development outside the female genital tract
Answer:
3. Fertilization outside and gestation inside the womb of mother

Question 11.
W hy is breastfeeding considered the best feeding?
1. enhances immunity
2. protects against allergies
3. reduces chances of immediate conception
4. all the above
Answer:
4. all the above

Question 12.
Assisted Reproductive Technology (ART), in which the ‘Test Tube Baby’ technique is employed, is known as
1. Gamete intrafallopian transfer (GIFT)
2. Intracytoplasmic sperm injection (ICSI)
3. In vitro fertilization and embryo transfer (IVF/ET)
4. Zygote intrafallopian transfer (ZIFT)
Answer:
3. In vitro fertilization and embryo transfer (IVF/ET)

Question 13.
Which of the following is a major constituent of oral contraceptive pills?
1. progesterone
2. oxytocin
3. relaxin
4. oiplex
Answer:
1. progesterone

Question 14.
Oral contraceptive pills help in preventing pregnancy by
1. killing the sperms in uterus
2. preventing implantation
3. preventing ovulation
4. both (2) and (3)
Answer:
4. both (2) and (3)

Question 15.
Amniocentesis is carried out for
1. digestion of amino acids
2. conversion of glucose to amino acids
3. taking out of cells near the foetus
4. killing of child before birth
Answer:
3. taking out of cells near the foetus

Question 16.
The Gamete Intra Fallopian Transfer (GIFT) technique is recommended for women
1. who cannot produce an ovum
2. who cannot retain the foetus inside uterus
3. whose cervical canal is too narrow to allow passage for the sperms
4. who cannot provide suitable environment for fertilization
Answer:
1. who cannot produce an ovum

Question 17.
Which of the following is a legally accepted method of birth control?
1. by abstaining from coitus from day 10 to 17 of the menstrual cycle
2. by having coitus at the time of day break
3. by a premature ejaculation during coitus
4. abortion by taking an appropriate medicine
Answer:
4. abortion by taking an appropriate medicine

Question 18.
Which of the following acts as a hormone-releasing Intrauterine Device (IUD)?
1. Multiload 375
2. LNG – 20
3. Cervical cap
4. Vault
Answer:
2. LNG – 20

Question 19.
Identify the incorrectly matched pair.
1. syphilis – Trichuris trichiura
2. sleeping sickness – Trypanosoma gambiense
3. dengue Fever – arbovirus
4. plague – Yersinia pestis
Answer:
1. syphilis – Trichuris trichiura

Question 20.
Progesterone pill helps to avoid pregnancy mainly by preventing
1. ovum formation
2. fertilization
3. implantation
4. none of these
Answer:
1. ovum formation

Question 21.
GIFT involves the transfer of
1. a mixture of sperms and ova into the uterus
2. embryo into the uterus
3. a mixture of sperms and ova into the Fallopian tube
4. zygote into the Fallopian tube
Answer:
3. a mixture of sperms and ova into the Fallopian tube

Question 22.
In vitro fertilisation is a technique that involves transfer of which of the following into the Fallopian tube? ( 2 )
1. Embryo only, up to 8-cell stage
2. Either zygote or early embryo up to 8-cell stage
3. Embryo of 32-cell stage
4. Zygote only
Answer:
2. Either zygote or early embryo up to 8-cell stage

Question 23.
Amniocentesis is mainly permitted for
1. detecting sex of the unborn foetus
2. artificial insemination
3. transfer of embryo into the uterus of a surrogate mother
4. detecting any genetic abnormality
Answer:
4. Detecting any genetic abnormality

Question 24.
Up to how many weeks is Medical Termination of Pregnancy (MTP) considered safe?
1. Eight weeks
2. Twelve weeks
3. Eighteen weeks
4. Six weeks
Answer:
2. Twelve weeks

Question 25.
Which of the following cannot be identified in a developing foetus through amniocentesis?
1. Down’s syndrome
2. Jaundice
3. Klinefelter’s syndrome
4. Sex of the foetus
Answer:
2. Jaundice

Question 26.
Tubectomy is a sterilization method in which
1. small part of the Fallopian tube is removed or tied up
2. ovaries are removed surgically
3. small part of vas deferens is removed or tied up
4. uterus is removed surgically
Answer:
1. small part of the Fallopian tube is removed or tied up

Question 27.
Copper-releasing intrauterine devices (IUDs) release Cu ions to
1. make uterus unsuitable for implantation
2. increase phagocytosis of sperms
3. suppress sperm motility
4. prevent ovulation
Answer:
3. suppress sperm motility

Question 28.
In assisted reproductive technology, IVF involves the transfer of
1. ovum into the Fallopian tube
2. zygote into the Fallopian tube
3. zygote into the uterus
4. embryo with 16 blastomeres into the Fallopian tube
Answer:
2. Zygote into the Fallopian tube

Question 29.
Which of the following is not a sexually transmitted disease?
1. Trichomoniasis
2. Encephalitis
3. Syphilis
4. Acquired Immunodeficiency Syndrome (AIDS)
Answer:
2. Encephalitis

Question 30.
Which virus is not transmitted through the semen of an infected male? ( 1 )
1. Chikungunya virus
2. Ebola virus
3. Hepatitis B virus
4. Human immunodeficiency virus
Answer:
1. Chikungunya virus

Question 31.
A childless couple can be helped through a technique called GIFT. What is the full form of GIFT?
1. Gamete Internal Fertilisation and Transfer
2. Germ cell Internal Fallopian Transfer
3. Gamete Inseminated Fallopian Transfer
4. Gamete Intra Fallopian Transfer
Answer:
4. Gamete Intra Fallopian Transfer

Question 32.
In embryo transfer, embryos produced by in vitro fertilisation are transferred into the
1. uterus
2. Fallopian tube
3. fimbriae
4. cervix
Answer:
1. uterus

Question 33.
Genital warts are caused by
1. Herpes simplex virus (HSV)
2. Treponema pallidum
3. Trichomonas vaginalis
4. Human papillomavirus (HPV)
Answer:
4. Human papillomavirus (HPV)

Question 34.
Which of the following techniques involves the direct introduction of gametes into the oviduct?
1. MTPS
2. ET
3. IVF
4. GIFT
Answer:
4. GIFT

Question 35.
Which of the following is a method of birth control?
1. IUDS
2. GIFT
3. HTF
4. IVF-ET
Answer:
1. IUDS

Question 36.
Syphilis is caused by
1. Treponema pallidum
2. Plasmodium
3. Neisseria gonorrhea
4. Entamoeba histolytica
Answer:
1. Treponema pallidum

Reviewing AP Inter 2nd Year Zoology Study Material Chapter 1 Human Reproduction Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Zoology 1st Lesson Human Reproduction Questions and Answers

IV. Very Short Answer Questions

Question 1.
What are the functions of Sertoli cells of the seminiferous tubules and the Leydig cells in man? (AP MAY-22)
Answer:
Sertoli cells :

1. Sertoli cells act as supporting and nourishing cells for developing sperm cells.
2. They also secrete Inhibin, a hormone that helps regulate FSH secretion.
3. These cells are present within the seminiferous tubules along with germ cells.

Leydig Cells

1. Leydig cells are found in the spaces between seminiferous tubules.
2. They produce and release androgens, particularly testosterone, which is essential for male reproductive functions.

Question 2.
Define spermiogenesis and spermiation. (AP MAR-25)
Answer:

1. Spermiogenesis: The process through which spermatids differentiate and mature into spermatozoa (sperms).
2. Spermiation: The process in which mature spermatozoa are released from the seminiferous tubules into their lumen.

Question 3.
Draw a labelled diagram of a sperm.
Answer:

Question 4.
What are the major components of seminal plasma?
Answer:
The important constituents of seminal plasma include:

1. Fructose
2. Calcium
3. Mucus
4. Ascorbic Acid (Vitamin C)

Question 5.
What is the menstrual cycle? Which hormones regulate menstrual cycle?
Answer:
1. The menstrual cycle is the regular reproductive cycle seen in human female primates.
2. During each cycle, the endometrium undergoes preparation for pregnancy and is shed if fertilization does not occur.
3. In human females, these cyclic changes generally occur every28-29 days.
4. The cycle is mainly controlled by the following hormones:

• Follicle-stimulating hormone (FSH) – Pituitary gland
• Luteinizing Hormone (LH) – Pituitary gland
• Estrogen – Ovary
• Progesterone – Ovary.

Question 6.
What is parturition? Which hormone are involved in inducing parturition?
Answer:

1. Parturition is the process of childbirth or the delivery of a baby from the uterus.
2. Oxytocin plays a major role in initiating and facilitating parturition.

Question 7.
How many eggs are released by a human ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins were fraternal?
Answer:

1. Normally, one ovum is released from a human ovary during each menstrual cycle.
2. In the case of identical twins, only one egg is released and later divides into two embryos.
3. In the case of fraternal twins, two separate eggs are released and fertilized independently.

V. Short Answer Questions 

Question 1.
Describe the microscopic structure of the testis in man.
Answer:

1. The testes of males are located in the scrotal sac, outside the abdominal cavity, because sperm production requires a temperature lower than normal body temperature.
2. Each testis is enclosed by a tough fibrous covering known as the tunica albuginea.
3. This covering extends inward and forms partitions called septa.
4. These septa divide the testis into nearly 250 lobules.
5. Every lobule contains 1 – 3 highly coiled seminiferous tubules.
6. The seminiferous tubules are lined by spermatogonia (germ cells) and Sertoli cells.
7. Spermatogonia develop into primary spermatocytes, which undergo meiosis to form spermatids.
8. Spermatids are transformed into mature sperm cells through spermiogenesis.
9. Sertoli cells provide nourishment to developing sperm and secrete Inhibin, which regulates FSH secretion.
10. Between the seminiferous tubules are Leydig (interstitial) cells.
11. Leydig cells synthesize and release androgens, mainly testosterone.
12. Seminiferous tubules open into the rete testis, which further connects to the vasa efferentia.
13. The vasa efferentia open into the epididymis, which is divided into the caput, corpus, and cauda regions.
14. The epididymis is highly coiled and serves as the site for sperm maturation and storage.

Question 2.
Describe the microscopic structure of the ovary of a woman.
Answer:

1. The ovaries are the primary female reproductive organs responsible for producing ova and female sex hormones.
2. A pair of ovaries is located in the lower abdominal region.
3. Each ovary is attached to the dorsal body wall by a fold of peritoneum called the mesovarium.
4. The outer surface of the ovary is covered by a simple cuboidal germinal epithelium.
5. Beneath this epithelium lies a dense connective tissue layer called the tunica albuginea.
6. The ovarian tissue is differentiated into an outer cortex and an inner medulla.
7. The medulla contains connective tissue, blood vessels, lymph vessels, and nerve fibers.
8. The cortex contains ovarian follicles at different stages of development.
9. Structures such as Graafian follicles, corpus luteum, and corpus albicans are found within the cortex.

Question 3.
Draw a labelled diagram of the male reproductive system.
Answer:

Question 4.
Draw a labelled diagram of the female reproductive system.
Answer:

Question 5.
What is spermatogenesis? Briefly describe the process of spermatogenesis in man.
Answer:
Spermatogenesis It is the process by which male gametes (sperms) are formed. In humans, this process begins at puberty.

Process :

1. Spermatogonial stem cells are present in the seminiferous tubules and divide repeatedly by mitosis.
2. Some spermatogonia differentiate into primary spermatocytes (2n = 46 chromosomes).
3. Each primary spermatocyte undergoes the first meiotic division to produce two haploid secondary spermatocytes (n = 23 chromosomes).
4. Secondary spermatocytes undergo the second meiotic division to form spermatids.
5. Each primary spermatocyte ultimately gives rise to four haploid spermatids.
6. Spermatids transform into mature spermatozoa through spermiogenesis.
7. Mature sperm heads remain embedded in Sertoli cells and are finally released by spermiation.
8. Hormones such as GnRH, FSH, and LH regulate spermatogenesis.
9. A mature sperm consists of a head, neck, middle piece, and tail.
10. The head bears an acrosome containing enzymes such as hyaluronidase that aid in fertilization.
11. The middle piece contains numerous mitochondria, which provide energy for sperm movement.

Question 6.
Describe the structure of a sperm cell with the help of a neat labelled diagram.
Answer:
A sperm cell is a microscopic, motile male gamete specialized for fertilization and enclosed by a plasma membrane.
It is divided into four major parts:
i) Head :

• Contains a haploid nucleus carrying genetic material.
• Covered by the acrosome, a cap-like structure.
• The acrosome contains enzymes that help the sperm penetrate the ovum during fertilization.

ii) Neck:

• A short connecting region between the head and middle piece.
• Contains centrioles involved in cell division after fertilization.

iii) Middle Piece:

• Contains numerous mitochondria arranged around the axial filament.
• Mitochondria generate ATP required for sperm motility.

iv) Tail (Flagellum):

• Long and slender structure responsible for locomotion.
• Propels the sperm through the female reproductive tract toward the ovum. Thus, the sperm is structurally adapted for movement and successful fertilization.

Question 7.
What is oogenesis? Give a brief account of oogenesis in a woman.
Answer:
Oogenesis is the process of formation of a mature female gamete (ovum). Unlike spermatogenesis, it begins during embryonic development.

1. Embryonic Stage :

• Millions of oogonia are formed in the fetal ovary.
• No new oogonia are produced after birth.
• Oogonia enter meiosis I and become primary oocytes.
• These primary oocytes remain arrested in prophase I.

2. Follicular Development:

• Each primary oocyte becomes surrounded by granulosa cells, forming a primary follicle.
• At puberty, about 60,000 – 80,000 primary follicles remain in each ovary.

3. Maturation:

• Primary follicles develop into secondary follicles and later into tertiary follicles.
• The tertiary follicle develops a fluid-filled cavity known as the antrum.

4. First Meiotic Division :

• The primary oocyte completes meiosis-I within the tertiary follicle.
• This unequal division produces a large secondary oocyte and a small first polar body.

5. Ovulation: The mature Graafian follicle ruptures and releases the secondary oocyte from the ovary.

6. Second Meiotic Division :

• Meiosis-II is completed only after fertilization.
• It produces a mature ovum and a second polar body.

Question 8.
Name the functions of the following :
(a) Corpus Luteum
(b) Fimbriae
(c) Acrosome
(d) Sperm Tail
Answer:
(a) Corpus Luteum :

• Secretes large amounts of progesterone.
• Progesterone maintains the endometrium and supports implantation and pregnancy.

(b) Fim briae :

• Finger-like projections present at the infundibulum of the fallopian tube.
• They help in collection of the ovum released from the ovary after ovulation.

(c) Acrosome:

• Cap-like structure present on the sperm head.
• Contains enzymes that help the sperm penetrate the coverings of the ovum during fertilization.

d) Sperm Tail:

• Responsible for sperm motility.
• Helps propel the sperm through the female reproductive tract toward the ovum.

VI. Long Answer Questions

Question 1.
Describe the Female Reproductive System of a woman with the help of a labelled diagram.
Answer:
The female reproductive organs are located in the pelvic cavity and include :
1) Ovaries :

• Ovaries are the primary female reproductive organs responsible for producing ova (female gametes) and female sex hormones.
• A pair of ovaries is situated on either side of the lower abdominal region.
• Each ovary is attached to the abdominal wall through a fold of peritoneum called the mesovarium.
• Every ovary consists of three main regions :

1. Germinal (ovarian) epithelium
2. Tunica albuginea
3. Stroma
The stroma is differentiated into an outer cortex and an inner medulla.

2. Fallopian Tubes:

• Each fallopian tube extends from the ovary to the uterus.
• The ovarian end of the tube is expanded into a funnel-shaped structure known as the infundibulum.
• The infundibulum bears finger-like projections called fimbriae.
• Fimbriae help in collecting the ovum released during ovulation.
• The fallopian tube is the usual site of fertilization and transports the ovum towards the uterus by peristaltic movements.

3. Uterus:

• The uterus is a single, hollow, muscular organ.
• It is located between the urinary bladder and rectum.
• It resembles an inverted pear and is richly supplied with blood vessels.
• The narrow lower region connecting the uterus to the vagina is called the cervix.
• The cervix and vagina together constitute the birth canal.
• The uterine wall consists of three layers: Outer Perimetrium, Middle Myometrium, Inner Endometrium
• The endometrium undergoes cyclic changes during the menstrual cycle.

4. Vagina:

• The vagina is a fibromuscular tube extending from the cervix to the vaginal opening.
• It is lined by non-keratinized stratified squamous epithelium and is highly vascular.

5. Vulva (External Genitalia):

• The term vulva (pudendum) refers to the external genital organs of the female.
• The vestibule is the region that contains the external openings of the urethra and vagina.
• The vaginal opening is partially covered by a thin mucous membrane called the hymen.
• The clitoris is homologous to the penis in males and contains erectile tissue.
• A fatty tissue pad covered by skin and pubic hair above the labia majora is called the mons pubis.

Accessory Reproductive Glands of Females: These include :
a) Bartholin’s glands,
b) Skene’s glands.

a) Bartholin’s glands:

• Also called Greater Vestibular Glands.
• They are located on either side of the vaginal opening and secrete mucus.

b) Skene’s Glands:

• Also known as Lesser Vestibular Glands.
• They are situated on the anterior wall of the vagina near the lower end of the urethra.

c) Mammary Glands:

• Mammary glands are paired structures composed of glandular tissue and varying amounts of fat.
• They contain alveoli, which produce and secrete milk after childbirth.
• Mammary ducts join to form a mammary ampulla, which opens into a lactiferous duct through which milk is delivered to the infant.

Question 2.
Describe the Male Reproductive System of a Man. Draw a Labelled Diagram of it. (AP MAR-16,17, 19,20,23,24)
Answer:
The male reproductive organs located in the pelvic region include:

1. Testes
2. Epididymis
3. Vas Deferens
4. Urethra
5. Penis
6. Accessory Glands

1. Testes :

• Testes are paired oval-shaped male primary reproductive organs.
• They are enclosed within a pouch called the scrotum, located outside the abdominal cavity.
• Sperm production requires a lower temperature; therefore, testes remain within the scrotum.
• The tunica albuginea forms septa that divide each testis into nearly 250 lobules.
• Each lobule contains 1 -3 highly coiled seminiferous tubules.
• Seminiferous tubules contain germinal epithelium and Sertoli cells. Germ cells produce sperm, while Sertoli cells nourish developing sperm.
• Testosterone regulates spermatogenesis and secondary sexual characteristics.
• Seminiferous tubules open into the rete testis, which continues into the vasa efferentia and epididymis

2. Epididymis:

• The epididymis is a long, tightly coiled tube located along the posterior side of each testis.
• Vasa efferentia open into the epididymis.
• It serves as a site for sperm maturation and temporary storage.

3. Vas Deferens :

• The vas deferens is a long, muscular tube.
• It begins from the tail of the epididymis, enters the abdominal cavity through the inguinal canal, and loops around the urinary bladder.

4. Urethra:

• The urethra originates from the urinary bladder and extends through the penis.
• It acts as a common passage for urine and semen.
• It opens to the exterior through the urethral meatus.

5. Penis:

• The penis functions as both a urinary organ and a copulatory organ that transfers sperm into the female reproductive tract.
• It consists of three columns of erectile tissue: Two corpora cavernosa and one corpus spongiosum
• The enlarged terminal part is the glans penis, covered by a loose fold of skin called the prepuce (foreskin).

6. Accessory Glands :
a) Seminal Vesicles :

• A pair of glands located behind the urinary bladder.
• Their secretion contains fructose, which provides energy for sperm.

b) Prostate Gland:

• Situated below the urinary bladder.
• Contributes about 15-30% of the seminal fluid.

c) Bulbourethral (Cowper’s) Glands :

• Located below the prostate gland.
• They secrete an alkaline fluid that lubricates and neutralizes the urethra during ejaculation.

Question 3.
Describe the Spermatogenesis and Oogenesis with Diagrammatic Representation.
Answer:
I) Spermatogenesis: Spermatogenesis is the process of sperm formation in the seminiferous tubules of the testes. It begins at puberty under the influence of GnRH.

1. Multiplication Phase: Immature germ cells called spermatogonia (2n = 46) divide repeatedly by mitosis.
2. Meiosis I: Primary spermatocytes undergo the first meiotic division to produce two haploid secondary spermatocytes.
3. Meiosis II: hi Secondary spermatocytes complete the second meiotic division to form four haploid spermatids.
4. Spermiogenesis: Spermatids differentiate into mature spermatozoa.
5. Spermiation: Mature sperm are released from Sertoli cells into the lumen of seminiferous tubules.

II) Oogenesis :
Oogenesis is the process of formation of a mature female gamete (ovum). It begins during embryonic life.

1. Embryonic Initiation: Millions of oogonia enter meiosis-I and become primary oocytes arrested in prophase I.
2. Follicular Development: Each primary oocyte is surrounded by granulosa cells to form a primary follicle. At puberty, about 60,000 – 80,000 follicles remain in each ovary.
3. Maturation: Primary follicles develop into secondary follicles and then tertiary follicles containing an antrum.
4. First Meiotic Division: The primary oocyte completes meiosis I, producing a large secondary oocyte and a first polar body.
5. Ovulation: The Graafian follicle ruptures and releases the secondary oocyte.
6. Second Meiotic Division: This division is completed only after fertilization, producing a haploid ootid (ovum) and a second polar body.

Question 4.
Explain the process of Fertilization and Implantation in Humans. Describe the major features of Embryonic Development at various months of pregnancy.
Answer:
1. Fertilization: Fertilization is the fusion of a sperm and ovum to form a zygote. It usually occurs in the ampullary region of the fallopian tube.

• Insemination and Transport: Semen is deposited in the vagina. Sperms travel through the cervix and uterus to reach the fallopian tube, where fertilization takes place.
• Contact and Entry: A sperm binds to the zona pellucida of the ovum and prevents entry of additional sperms.
• Acrosomal Reaction: Enzymes released from the acrosome help the sperm penetrate the ovum.
• Completion of Meiosis: Sperm entry stimulates completion of meiosis-II in the secondary oocyte, producing an ovum and second polar body.
• Zygote Formation: Fusion of male and female pronuclei results in a diploid zygote (2n). The sex of the baby depends on whether the fertilizing sperm carries an X or Y chromosome.

2. Implantation: Implantation is the process by which the developing embryo becomes attached to and embedded within the endometrium.

• Cleavage and Morula Formation: The zygote undergoes repeated mitotic divisions, producing blastomeres. The 8-16 cell stage is called the morula.
• Blastocyst Formation: The morula develops into a blastocyst composed of an outer trophoblast and inner cell mass.
• Attachment to Endometrium: The trophoblast attaches to the uterine endometrium.
• Embedding: The blastocyst becomes completely embedded within the uterine lining.
• Hormonal Support: Progesterone secreted by the corpus luteum maintains the endometrium and supports implantation.

3. Major Stages of Embryonic Development:

• End of First Month: The embryonic heart is formed.
• End of Second Month: Limbs and digits become visible.
• End of 12 Weeks (First Trimester): Most major organ systems are formed, and external genitalia become distinguishable.
• Fifth Month: Foetal movements can be felt, and hair appears on the head.
• End of 24 Weeks (Second Trimester): Fine body hair develops, eyelashes appear, and eyelids separate.
• End of Nine Months: The foetus becomes fully developed and ready for birth (parturition).

I. Multiple Choice Questions

Question 1.
Humans are ………………………….
1. Oviparous
2. Viviparous
3. Ovoviviparous
4. Parthenogenetic
Answer:
2. Viviparous

Question 2.
The reason behind the presence of testes outside the abdomen is :
1. To decrease the temperature up to 2°C to 2.5°C for spermatogenesis.
2. To increase the temperature up to 2°C to 2.5°C for spermatogenesis.
3. There is no sufficient space in abdominal cavity.
4. To prevent excessive production of sperms.
Answer:
1. To decrease the temperature up to 2°C to 2.5°C for spermatogenesis.

Question 3.
Which of the following depicts the correct pathway of transport of sperms?
1. Vasa Efferentia → Rete Testis → Vas Deference → Epididymis
2. Rete Testis → Epididymis → Vasa Efferentia → Vas Deference
3. Rete Testis → Vas Deference → Vasa Efferentia → Epididymis
4. Rete Testis → Vasa Efferentia → Epididymis → Vas Deferens
Answer:
4. Rete Testis → Vasa Efferentia → Epididymis → Vas Deferens

Question 4.
Which of the following acts as temporary endocrine tissue after ovulation in human females?
1. Corpus albicans
2. Corpus luteum
3. Graafian follicle
4. Tertiary follicle
Answer:
2. Corpus luteum

Question 6.
The correct sequence of milk passage in mammary gland, beginning from alveoli, would be:
1. Mammary tubules → Mammary ampulla → Mammary ducts → Lactiferous ducts
2. Lactiferous ducts → Mammary ducts → Mammary ampulla → Mammary tubules
3. Lactiferous ducts → Mammary ampulla → Mammary ducts → Mammary tubules
4. Mammary tubules → Mammary ducts → Mammary ampulla → Lactiferous ducts
Answer:
4. Mammary tubules → Mammary ducts → Mammary ampulla → Lactiferous ducts

Question 7.
Assertion: The seminal plasma along with the sperms constitute the semen.
Reason: For normal fertility, at least 40 per cent of ejaculated sperms must have normal shape and size, and at least 60 per cent of them must show vigorous motility. ,
1. If both assertion and reason are true and reason is the correct explanation of assertion.
2. If both assertion and reason are true but reason is not the correct explanation of assertion.
3. If assertion is true but reason is false.
4. If Assertion false and Reason is true.
Answer:
3. If assertion is true but reason is false.

Question 8.
The second meiotic division of oocyte is completed during
1. Childbirth
2. Puberty
3. Ovulation
4. Fertilization
Answer:
4. Fertilization

Question 9.
Most of the major organ systems in foetal stage are formed
1. By the end of 151 month
2. By the end of 2nd month
3. By the end of 3rd month
4. By the end of 3rd week
Answer:
3. By the end of 3rd month

Question 10.
The signal for foetal ejection reflex in human female originates from
1. Progesterone
2. Differentiation of mammary glands
3. Fully developed foetus and placenta
4. Sudden drop of oxytocin
Answer:
3. Fully developed foetus and placenta

Question 11.
The act of delivering a foetus at the end of pregnancy is called …………………….. .
1. Parturition
2. Gestation
3. Coitus
4. Lactation
Answer:
1. Parturition

II. Fill in the Blanks

1. Testes are situated outside the abdominal cavity within a pouch called ……………………….. .
Answer:
Scrotum

2. The seminiferous tubules of the testis open into the vasa efferentia through …………………. .
Answer:
Rete testis

3. The part of fallopian tube closer to the ovary with funnel-shaped structure called ……………………. .
Answer:
Infundibulum

4. The process of release of ovum from a mature follicle is called ………………………. .
Answer:
Ovulation

5. Ovulation is induced by a hormone called ………………………… .
Answer:
Luteinizing hormone (LH)

6. The uterine layer that exhibits strong contraction during delivery of the baby is ………………………….. .
Answer:
Myometrium.

7. The fusion of male and female gametes is called …………………………….. .
Answer:
Fertilization

8. The first menstruation is called ………………………….. .
Answer:
Menarche.

9. Zygote divides to form …………………………… which is implanted in uterus.
Answer:
Blastocyst

10. The structural and functional unit between foetus and uterus is called ………………………… .
Answer:
placenta

III. One Word Answer Questions

Question 1.
How many seminiferous tubules are present in every testicular lobule in which sperm are produced?
Answer:
1 to 3

Question 2.
Name the hormones that are synthesized and secreted by Leydig cells.
Answer:
Androgens

Question 3.
The fingerlike projections of the infundibulum of fallopian tube are called as?
Answer:
Fimbriae

Question 4.
What is the tiny finger-like structure which lies at the upper junction of the two labia minora above the urethral opening?
Answer:
Clitoris

Question 5.
Which layer undergoes cyclic changes in menstrual cycle?
Answer:
Endometrium

Question 6.
By the end of which month of gestation is the heart formed in a human embryo?
Answer:
By the end of the first month

Question 7.
The milk produced in the initial few’ days of lactation which is rich in antibodies called ?
Answer:
Colostrum

Question 8.
How many eggs do you think were released by the ovary of a female dog which gave birth to 6 puppies?
Answer:
6 (Six) eggs

Question 9.
What is the cessation of menstrual cycle called?
Answer:
Menopause

Objective Questions

Question 1.
In which type of reproduction are genetic variations commonly observed?
1. Schizogony
2. Sexual reproduction
3. Multiple fission
4. Budding
Answer:
2. Sexual reproduction

Question 2.
Which structure forms the outer covering of the ovary?
1. Mesovarium
2. Germinal epithelium
3. Columnar epithelium
4. Ciliated epithelium
Answer:
2. Germinal epithelium

Question 3.
Cleavage in human beings is classified as :
1. Equal
2. Holoblastic
3. Meroblastic
4. Determinate
Answer:
2. Holoblastic

Question 4.
What is the primary role of the epididymis?
1. Activation of the sperms only
2. Temporary storage of the sperms until they mature
3. Spermatogenesis and spermiogenesis
4. Nourishing of the sperms only
Answer:
2. Temporary storage of the sperms until they mature

Question 5.
What is the basic characteristic feature of sexual reproduction?
1. Fusion of two adult individuals
2. Fusion of male and female gametes produced by meiosis
3. Fusion of gametes produced by mitosis
4. Fusion of male and female haploid gametes produced by mitosis
Answer:
2. Fusion of male and female gametes produced by meiosis

Question 6.
Testes remain attached to the scrotal sac posteriorly through :
1. Dartos muscle
2. Spermatic cords
3. Gubernaculum
4. Rachis
Answer:
3. Gubernaculum

Question 7.
Meiosis takes place in :
1. Both (3) and (4)
2. Spermatogonia and oogonia
3. Primary and secondary oocytes
4. Primary and secondary spermatocytes
Answer:
1. Both (3) and (4)

Question 8.
Seminal plasma receives secretions from :
1. Bulbourethral glands
2. Seminal vesicles
3. Prostate gland
4. All of the above
Answer:
4. All the above

Question 9.
Which part of the fallopian tube is nearest to the ovary?
1. Cervix
2. Ampulla
3. Infundibulum
4. Isthmus
Answer:
3. Infundibulum

Question 10.
Which enzyme helps sperm penetrate the corona radiata and zona pellucida?
1. Citric acid
2. Hyaluronidase
3. Hydrochloric acid
4. Protease
Answer:
2. Hyaluronidase

Question 11.
Implantation in humans generally occurs on :
1. 12th day after copulation
2. 6th day after ovulation
3. 6th day after fertilization
4. 6th day after menstruation
Answer:
4. 6th day after menstruation

Question 12.
Which enzyme plays an important role during implantation?
1. Lipases
2. Amylases
3. Progesterone
4. Proteases
Answer:
4. Proteases

Question 13.
At what stage does the foetal heart begin to beat?
1. End of first trimester
2.2nd month
3. 4th week
4. 14th day
Answer:
3. 4th week

Question 14.
Which gland secretes the highest amount of fructose?
1. Cowper’s gland
2. Prostate gland
3. Tyson gland
4. Seminal vesicle
Answer:
4. Seminal vesicle

Question 15.
In mammals, failure of testes to descend into the scrotum is termed :
1. Castration
2. Impotency
3. Paedogenesis
4. Cryptorchidism
Answer:
4. Cryptorchidism

Question 16.
The vas deferens originates from :
1. Rete testis
2. Corpus epididymis
3. Caput epididymis
4. Cauda epididymis
Answer:
4. Cauda epididymis

Question 17.
Which accessory reproductive gland is unique to male mammals?
1. Prostate gland
2. All
3. Pineal gland
4. Bartholin’s gland
Answer:
1. Prostate gland

Question 18.
Seminal vesicle opens at the junction of:
1. Vas deferens and testis
2. Prostate and urethra
3. Prostate and vas deferens
4. Prostate and Cowper’s gland
Answer:
3. Prostate and vas deferens

Question 19.
Developing sperms receive nourishment from :
1. Connective tissue cells
2. Interstitial cells
3. None
4. Sertoli cells
Answer:
4. Sertoli cells

Question 20.
The egg released during ovulation in humans is at which stage?
1. Mature ovum stage
2. Secondary oocyte stage
3. Oogonial stage
4. Primary oocyte stage
Answer:
2. Secondary oocyte stage

Question 21.
The endocrine structure formed after ovulation from the ruptured Graafian follicle is:
1. Corpus albicans
2. Corpus luteum
3. Corpus striatum
4. Corpus callosum
Answer:
2. Corpus luteum

Question 22.
Which female structure is considered homologous to the male prostate gland?
1. Bulbourethral gland
2. Bartholin’s gland
3. Clitoris
4. None of the above
Answer:
4. None of the above

Question 23.
The luteal phase is also known as:
1. Secretory phase
2. Menstrual flow phase
3. Follicular phase
4. Proliferative phase
Answer:
1. Secretory phase

Question 24.
Which extraembryonic membrane prevents the embryo from drying out inside the uterus?
1. Allantois
2. Yolk sac
3. Chorion
4. Amnion
Answer:
4. Amnion

Question 25.
Which membrane contributes to the formation of the urinary bladder of the embryo?
1. Yolk sac
2. Chorion
3. Minion
4. Allantois
Answer:
4. Allantois

Question 26.
Spermatogenesis is mainly regulated by the influence of:
1. LH
2. ADH
3. STH
4. FSH
Answer:
4. FSH

Question 27.
Which statement is incorrect regarding oogenesis?
1. Growth phase
2. Equal meiotic division
3. Formation of polar bodies
4. Unequal meiotic division
Answer:
2. Equal meiotic division

Question 28.
Prostaglandins are synthesized from:
1. Carbohydrate
2. Steroid
3. Fatty acids
4. Amino acids
Answer:
3. Fatty acids

Question 29.
The embryo at the sixteen-cell stage is known as:
1. Blastomere
2. Gastrula
3. Morula
4. Blastula
Answer:
3. Morula

Question 30.
Which phase of the menstrual cycle normally continues for about 7-8 days?
1. Ovulatory phase
2. Menstruation
3. Follicular phase
4. Luteal phase
Answer:
3. Follicular phase

Question 31.
Corpus luteum and macula lutea share the common feature that they are:
1. Characterised by yellow colour
2. Source of hormones
3. Found in human ovaries
4. Contributory in maintaining pregnancy
Answer:
1. Characterised by yellow colour

Question 32.
Fertilin is produced and released by :
1. Epididymis
2. Testes
3. Egg surface
4. Sperm head tip
Answer:
3. Egg surface

Question 33.
The secretory phase of the menstrual cycle is alternatively termed :
1. Follicular phase and lasts for about 13 days
2. Follicular phase and lasts for about 6 days
3. Luteal phase and lasts for about 13 days
4. Luteal phase and lasts for about 6 days
Answer:
3. Luteal phase and lasts for about 13 days

Question 34.
The signals responsible for initiating parturition arise from:
1. Fully developed foetus only
2. Placenta as well as fully developed foetus
3. Oxytocin released from maternal pituitary
4. Placenta only
Answer:
2. Placenta as well as fully developed foetus

Question 35.
The second maturation division of the mammalian ovum takes place:
1. Until nucleus of sperm and ovum fuse
2. Shortly after ovulation before entry into fallopian tube
3. In Graafian follicle soon after first maturation division
4. Until after sperm has penetrated into ovum
Answer:
4. Until after sperm has penetrated into ovum

Question 36.
Following ovulation, the follicle transforms into :
1. Corpus callosum
2. Corpus cavemosum
3. Corpus luteum
4. Corpus albicans
Answer:
3. Corpus luteum

Question 37.
Bartholin’s glands are located :
1. On either side of vas deferens in humans
2. On either side of vagina in humans
3. On the reduced tail end of birds
4. On the sides of the head of some amphibians
Answer:
2. On either side of vagina in humans

Question 38.
What will be the consequence if the vas deferens is cut?
1. Sperms are non-nucleated
2. Spermatogenesis does not occur
3. Semen is without sperms
4. Sperms are nonmotile
Answer:
3. Semen is without sperms

Question 39.
Functional maturation of sperms occurs in :
1. Epididymis
2. Vagina
3. Oviduct
4. All of these
Answer:
1. Epididymis

Question 40.
Which hormone promotes the development of female secondary sexual characters?
1. Testosterone
2. Androgen
3. Estrogen
4. Progesterone
Answer:
3. Estrogen

Reviewing AP Inter 2nd Year Botany Study Material Chapter 6 Ecosystem Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Botany 6th Lesson Ecosystem Questions and Answers

IV. Very Short Answer Questions

Question 1.
Define an ecosystem.
Answer:

1. An ecosystem is the basic functional unit of the biosphere where organisms interact with one another as well as with their surrounding physical environment.
2. These interactions involve the transfer of energy and cycling of nutrients within the system. Examples: Pond, Lake.

Question 2.
Name any two decomposers found in a pond ecosystem.
Answer:
Common decomposers present in a pond ecosystem include :

1. Fungi
2. Bacteria
3. Flagellates

Question 3.
What is humus?
Answer:
Humus is a dark-coloured, amorphous organic substance formed during the decomposition of organic matter through the process of humification.

Question 4.
Mention any two climatic factors that affect the rate of decomposition.
Answer:
Two important climatic factors influencing decomposition are :

1. Temperature
2. Soil moisture.

Question 5.
What is meant by a trophic level?
Answer:
A trophic level refers to the feeding position occupied by an organism in a food chain based on the source from which it obtains food and energy.

Question 6.
What is an ecological pyramid?
Answer:
An ecological pyramid is a diagrammatic representation that illustrates the relationship among organisms at different trophic levels in terms of number, biomass, or energy.

V. Short Answer Questions

Question 1.
Describe the types and importance ecological pyramids.
Answer:
An ecological pyramid is a diagrammatic representation that illustrates the feeding and energy relationships among organisms at different trophic levels in an ecosystem. It generally has a broad base consisting of producers and a narrow top occupied by top consumers.

Types of Ecological Pyramids :
1. Pyramid of Numbers:

• Represents the number of individuals present at each trophic level.
• Generally remains upright. Example: Grassland ecosystem.
• May become inverted in certain ecosystems. Example: A single tree supporting numerous insects.

2. Pyramid of Biomass:

• Shows the total biomass (living matter) present at each trophic level.
• Usually upright in terrestrial ecosystems.
• Can be inverted in aquatic ecosystems where the biomass of fishes exceeds that of phytoplankton.

3. Pyramid of Energy:

• Depicts the amount of energy available at successive trophic levels.
• It is always upright and never inverted.
• Since energy is lost as heat at every trophic level (10% law), higher trophic levels possess progressively less energy.

Importance of Ecological Pyramids :

• Illustrates energy transfer Helps in understanding how energy moves through different trophic levels and flows the 10% law.
• Explains trophic relationships: Shows the relationship between producers and consumers in terms of number, biomass, and energy.
• Facilitates ecosystem comparison: Upright and inverted pyramids help compare different ecosystems such as grasslands and aquatic systems.
• Indicates ecosystem stability: Helps in understanding the balance, structure, and functioning of ecosystems.

Question 2.
Distinguish between gross primary productivity and net primary productivity.
Answer:

Question 3.
Explain the different steps involved in the process of decomposition.
Answer:

1. Decomposition is the breakdown of dead organic matter (detritus) into simpler inorganic substances such as carbon dioxide, water, and nutrients by decomposers.
2. It is predominantly an oxygen-dependent process and occurs through several stages.
3. The first stage is fragmentation, where detritivores like earthworms break detritus into smaller pieces, increasing the surface area available for microbial activity.
4. This is followed by leaching, in which water dissolves soluble nutrients and carries them into deeper soil layers.
5. The next stage is catabolism, where bacteria and fungi release enzymes that convert complex organic compounds into simpler substances.
6. Subsequently, humification occurs, resulting in the formation of humus, a dark-coloured amorphous substance.
7. Humus is resistant to further decomposition and serves as a nutrient reservoir.
8. Finally, mineralisation takes place, where microbes break down humus and release inorganic nutrients into the soil, making them available to plants.
9. Fragmentation, leaching and catabolism often occur simultaneously.
10. The rate of decomposition is influenced by factors such as temperature, moisture and the chemical composition of detritus.

Question 4.
Differentiate between grazing food chain and detritus food chain.
Answer:

VI. Long Answer Questions

Question 1.
Describe the components of an ecosystem.
Answer:

• An ecosystem is a functional unit of nature where living organisms interact with one another and with their surrounding environment.
• It consists of abiotic (non-living) and biotic (living) components, along with structural and – Wabr functional features.

Abiotic Components (Non-living): Abiotic factors include all physical and chemical elements that influence living organisms.
i) Physical and inorganic materials :

• Air supplies oxygen for respiration and carbon dioxide for photosynthesis.
• Water is essential for life processes.
• Soil provides minerals and support for plant growth.

ii) Dissolved substances:

• Nutrients such as nitrogen, phosphorus, and minerals occur in soil and water.
• These nutrients are absorbed by plants and transferred through food chains.

iii) Climatic factors:

• Sunlight, temperature, rainfall, humidity, and wind regulate photosynthesis, growth, and reproduction.
• Sunlight serves as the primary source of energy in most ecosystems.

2. Biotic Components (Living): Biotic components include all living organisms classified according to their role in energy transfer.
i) Producers (Autotrophs):

• Green plants, algae, and phytoplankton convert solar energy into chemical energy through photosynthesis.
• They form the foundation of food chains.

ii) Consumers (Heterotrophs):

• Depend on producers or other organisms for food.
• Primary consumers feed on plants.
• Secondary and tertiary consumers feed on other animals.

iii) Decomposers (Saprotrophs):

• Bacteria and fungi decompose dead plants, animals, and organic matter.
• They convert complex substances into simple nutrients and recycle them back to the environment.

3. Structural Features of an Ecosystem :

• Species composition: Refers to the variety and abundance of species present in an ecosystem. Greater diversity generally indicates higher stability.
• Stratification: Organisms are arranged in different vertical layers. For example, forests show canopy, shrub, and ground layers.

4. Functional Aspects of an Ecosystem :

• Productivity: Rate at which producers synthesize organic matter through photosynthesis.
• Decomposition: Breakdown of dead organic matter into simpler substances.
• Energy flow: Energy moves from the sun to producers and then to consumers in a unidirectional manner.
• Nutrient cycling: Continuous circulation of nutrients such as carbon, nitrogen, and phosphorus between living and non-living components.

Question 2.
Give an account of energy flow in an ecosystem.
Answer:
Flow of Energy in an Ecosystem :

1. The Sun is the ultimate source of energy for all ecosystems.
2. Solar energy is captured by plants and transferred through various trophic levels.
3. Less than 50% of the incoming solar radiation is photosynthetically active radiation (PAR).
4. Plants utilize only about 2-10% of PAR, which supports the entire living world.
5. All organisms depend directly or indirectly on producers for energy.
6. According to the First Law of Thermodynamics, energy can neither be created nor destroyed; it only changes from one form to another.
7. The Second Law of Thermodynamics states that some energy is lost as heat at every trophic level, reducing the amount available to the next level.
8. Energy transfer through trophic levels is known as energy flow.
9. Available energy decreases progressively at higher trophic levels.
10. When organisms die, their stored energy becomes available to decomposers.
11. Each trophic level possesses a certain amount of living material called the standing crop.
12. Standing crop represents biomass and may be expressed as fresh weight or dry weight, with dry weight being more accurate.

I. Multiple Choice Questions

Question 1.
An ecosystem can best be defined as :
1. A collection of similar species living in a habitat.
2. A group of plants and animals living together without interaction.
3. A functional unit where living organisms interact with each other and the environment.
4. The population of a single species in a given area.
Answer:
3. A functional unit where living organisms interact with each other and the environment.

Question 2.
Which of the following is not a natural ecosystem?
1. Desert
2. Forest
3. Aquarium
4. Lake
Answer:
3. Aquarium

Question 3.
Vertical distribution of different species occupying various levels ¡n an ecosystem is called:
1. Stratification
2. Speciation
3. Decomposition
4. Succession
Answer:
1. Stratification

Question 4.
The rate of biomass production per unit area and time is known as:
1. Decomposition
2. Productivity
3. Energy flow
4. Respiration
Answer:
2. Productivity

Question 5.
Net Primary Productivity (NPP) is calculated as:
1. GPP+R
2. GPP-R
3. R-GPP
4. GPP × R
Answer:
2. GPP-R

Question 6.
The process of breaking down complex organic matter into simple inorganic substances is known as :
1. Mineralization
2. Decomposition
3. Stratification
4. Catabolism
Answer:
2. Decomposition

Question 7.
The energy transfer from one trophic level to another follows the
1. 50% law
2. 25% law
3. 10% law
4. 90% law
Answer:
3. 10% law

Question 8.
In a terrestrial ecosystem, the major conduit for energy flow is the
1. Detritus food chain
2. Grazing food chain
3. Inverted pyramid
4. Microbial chain
Answer:
1. Detritus food chain

Question 9.
Which ecological pyramid is always upright?
1. Pyramid of numbers
2. Pyramid of biomass
3. Pyramid of energy
4. Pyramid of productivity
Answer:
3. Pyramid of energy

Question 10.
The pyramid of biomass in the sea is generally inverted because:
1. Phytoplankton have a higher biomass than that of fishes.
2. Fishes have more biomass than that of phytoplankton.
3. Energy flow in the sea is bidirectional.
4. Decomposers dominate the marine ecosystem.
Answer:
2. Fishes have more biomass than that of phytoplankton.

II. Fill in the Blanks

1. The natural interconnection of food chains make ………………………… .
Answer:
Food web

2. Each trophic level has a certain mass of living material at a particular time called …………………………. .
Answer:
Standing crop

3. …………………………… is the process through which water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
Answer:
Leaching

Question 4.
Common decomposers in pond ecosystems are ……………………………….. .
Answer:
Bacteria, fungi, and flagellates

5. Measurement of biomass in terms of ……………………….. weight is more accurate
Answer:
Dry

6. In aquatic ecosystems, the limiting factor for the productivity is ………………………….. .
Answer:
Light

7. The rate of decomposition is slower if detritus is rich in lignin and ……………………….. .
Answer:
Chitin

8. Only about ………………………….. percent of the incident solar radiation is photosynthetically active radiation (PAR).
Answer:
Less than 50

9. ………………………… play a vital role in the ecosystem but not given any place in ecological pyramids.
Answer:
Saprophytes

10. Plants are called …………………………. because they fix carbon dioxide.
Answer:
Producers

III. One Word Answer Questions

Question 1.
What is the natural structural and functional unit where living organisms interact with their environment?
Answer:
Ecosystem

Question 2.
What do we call organisms that prepare their own food using sunlight?
Answer:
Producers

Question 3.
Which term describes the rate of production of biomass or organic matter per unit area over time?
Answer:
Productivity

Question 4.
Which organisms break down dead organic matter into inorganic nutrients?
Answer:
Decomposers

Question 5.
What is the dark, amorphous substance formed during the process of humification?
Answer:
Humus

Question 6.
What is the primary source of energy for all ecosystems on Earth?
Answer:
Sun

Question 7.
What is the sequence of organisms through which energy is transferred in an ecosystem called?
Answer:
Food chain

Question 8.
Which trophic level is occupied by herbivores in a food chain?
Answer:
Second trophic level

Question 9.
Which ecological pyramid is always upright and never inverted?
Answer:
Pyramid of Energy

Question 10.
Which process releases inorganic nutrients from humus through microbial activity?
Answer:
Mineralisation

Objective Questions

Question 1.
The interaction between organisms and their physical surroundings leads primarily to:
1. Species extinction
2. Formation of functional units
3. Random associations
4. Only energy loss
Answer:
2. Formation of functional units

Question 2.
A pond is regarded as a self-sustaining ecosystem because it exhibits components such as productivity, energy flow, and:
1. Mutation
2. Decomposition
3. Evolution
4. Stratification
Answer:
2. Decomposition

Question 3.
The layered arrangement of trees, shrubs, and grasses in a forest ecosystem is known as:
1. Biomagnification
2. Food chain
3. Stratification
4. Trophic collapse
Answer:
3. Stratification

Question 4.
In pond ecosystems, the chief autotrophic organisms are:
1. Earthworms
2. Phytoplankton and algae
3. Fishes
4. Zooplankton
Answer:
2. Phytoplankton and algae

Question 5.
Consumers in a pond ecosystem are organisms that:
1. Decompose matter
2. Feed on producers or other consumers
3. Produce their own food
4. Fix nitrogen
Answer:
2. Feed on producers or other consumers

Question 6.
Decomposers primarily convert organic matter into:
1. Proteins
2. Lipids
3. Inorganic substances
4. Complex polymers
Answer:
3. Inorganic substances

Question 7.
Energy flow in an ecosystem is considered unidirectional because it:
1. Remains constant
2. Moves only upward
3. Flows and is lost as heat
4. Cycles continuously
Answer:
3. Flows and is lost as heat

Question 8.
Productivity is generally expressed in units such as:
1. kg/hour
2. mol/L
3. g/m²/year
4. m/s
Answer:
3. g/m²/year

Question 9.
Gross Primary Productivity (GPP) includes the total organic matter produced along with:
1. Decomposition
2. Respiration losses
3. Secondary production
4. Only stored biomass
Answer:
2. Respiration losses

Question 10.
Net Primary Productivity (NPP) represents the biomass available to:
1. Only decomposers
2. Only bacteria
3. Heterotrophs
4. Only producers
Answer:
3. Heterotrophs

Question 11.
Although oceans occupy nearly 70% of Earth’s surface, their productivity is comparatively low mainly due to:
1. High salinity
2. Excess sunlight
3. Lack of nutrients
4. High oxygen
Answer:
3. Lack of nutrients

Question 12.
Biomass production by heterotrophic organisms is referred to as:
1. Parasites
2. Producers
3. Consumers
4. Decomposers
Answer:
3. Consumers

Question 13.
In the decomposition process, fragmentation is mainly performed by:
1. Carnivores
2. Parasites
3. Detritivores
4. Plants
Answer:
3. Detritivores

Question 14.
The downward transport of nutrients into the soil due to water is called:
1. Water action
2. Photosynthesis
3. Chemical reactions
4. Evaporation
Answer:
1. Water action

Question 15.
During decomposition, catabolism is associated with:
1. Energy storage
2. Reproduction
3. Breaking down substances
4. Building complex molecules
Answer:
3. Breaking down substances

Question 16.
Which substance is produced as a result of humification?
1. Proteins
2. Humus
3. Lipids
4. Glucose
Answer:
2. Humus

Question 17.
Humus is characterized by being:
1. Rich in microbes
2. Inorganic
3. Resistant to decomposition
4. Highly degradable
Answer:
3. Resistant to decomposition

Question 18.
Decomposition proceeds more rapidly when detritus is rich in:
1. Chitin
2. Wax
3. Nitrogen
4. Lignin
Answer:
3. Nitrogen

Question 19.
Warm and moist environmental conditions accelerate decomposition by:
1. Preventing leaching
2. Enhancing microbial activity
3. Slowing microbial activity
4. Stopping reactions
Answer:
2. Enhancing microbial activity

Question 20.
The rate of decomposition generally declines under :
1. Increase respiration
2. Increase decomposition
3. Decrease decomposition
4. Have no effect
Answer:
3. Decrease decomposition

Question 21.
Plants can utilize only a small fraction of solar radiation because :
1. It is reflected by soil
2. Only PAR is useful
3. It is converted to heat
4. It is absorbed by animals
Answer:
2. Only PAR is useful

Question 22.
Approximately what percentage of PAR is captured by plants?
1. 80 – 90%
2. 50 – 70%
3. 2 – 10%
4. 20 – 30%
Answer:
3. 2 – 10%

Question 23.
Producers are important in ecosystems because they :
1. Consume energy
2. Reduce oxygen
3. Fix solar energy
4. Decompose matter
Answer:
3. Fix solar energy

Question 24.
Primary consumers are mainly
1. Decomposers
2. Carnivores
3. Omnivores
4. Herbivores
Answer:
4. Herbivores

Question 25.
The grazing food chain originates from:
1. Carnivores
2. Producers
3. Detritus
4. Decomposers
Answer:
2. Producers

Question 26.
The detritus food chain originates from:
1. Omnivores
2. Dead organic matter
3. Live plants
4. Herbivores
Answer:
2. Dead organic matter

Question 27.
Decomposers are commonly known as saprotrophs because they:
1. Fix nitrogen
2. Store nutrients
3. Decompose organic matter
4. Produce sap
Answer:
3. Decompose organic matter

Question 28.
Food webs are formed due to:
1. Absence of consumers
2. Interconnection of food chains
3. Single feeding relationships
4. Lack of producers
Answer:
2. Interconnection of food chains

Question 29.
Producers occupy which trophic level in a food chain?
1. Third trophic level
2. First trophic level
3. Fourth trophic level
4. Second trophic level
Answer:
2. First trophic level

Question 30.
Herbivores are placed in which trophic level?
1. Fourth level
2. First level
3. Second level
4. Third level
Answer:
3. Second level

Question 31.
Energy availability decreases at higher trophic levels mainly because of:
1. Increased consumption
2. Storage
3. Heat loss
4. Transfer efficiency
Answer:
3. Heat loss

Question 32.
The term “standing crop” refers to:
1. Decomposition rate
2. Number of crops harvested
3. Biomass at a given time
4. Productivity rate
Answer:
3. Biomass at a given time

Question 33.
Biomass estimation is more accurate when measured as dry weight because:
1. It simplifies counting
2. It removes water variability
3. It increases value
4. It is lighter
Answer:
2. It removes water variability

Question 34.
According to the 10% law:
1. Energy is constant
2. 90% energy is transferred
3. Only 10% energy is transferred
4. Energy increases upward
Answer:
3. Only 10% energy is transferred

Question 35.
The number of trophic levels in an ecosystem is mainly restricted by:
1. Oxygen
2. Water
3. Energy loss
4. Space
Answer:
3. Energy loss

Question 36.
Ecological pyramids depict relationships based on:
1. Only biomass
2. Energy, biomass, number
3. Only energy
4. Only number
Answer:
2. Energy, biomass, number

Question 37.
The base of an ecological pyramid is occupied by:
1. Carnivores
2. Producers
3. Consumers
4. Decomposers
Answer:
2. Producers

Question 38.
Which ecological pyramid is never inverted?
1. Variable
2. Upright
3. Inverted
4. Irregular
Answer:
2. Upright

Question 39.
In marine ecosystems, the biomass pyramid often appears inverted because:
1. Decomposers dominate
2. Fish biomass is higher
3. Producers dominate
4. Energy flow is cyclic
Answer:
2. Fish biomass is higher

Question 40.
Ecological pyramids in most ecosystems are upright mainly because:
1. Consumers dominate
2. Energy increases upward
3. Producers are more abundant
4. Producers are fewer
Answer:
3. Producers are more abundant

Question 41.
Humans are generally categorized as:
1. Producers
2. Only herbivores
3. Omnivores
4. Only carnivores
Answer:
3. Omnivores

Question 42.
Which of the following is not represented in ecological pyramids?
1. Consumers
2. Herbivores
3. Decomposers
4. Producers
Answer:
3. Decomposers

Question 43.
In forest ecosystems, stratification minimizes competition among plants by:
1. Eliminating weaker species
2. Allowing species to occupy different vertical levels
3. Preventing decomposition
4. Increasing energy loss
Answer:
2. Allowing species to occupy different vertical levels

Question 44.
Autotrophs in pond ecosystems synthesize organic matter using :
1. Thermal energy
2. Solar energy
3. Mechanical energy
4. Chemical energy
Answer:
2. Solar energy

Question 45.
Net Primary Productivity (NPP) mainly denotes :
1. Energy lost in decomposition
2. Energy used in respiration
3. Total biomass
4. Growth rate of plants
Answer:
2. Energy used in respiration

Question 46.
Earthworms are called farmers’ friends because they improve soil fertility through:
1. Increasing temperature
2. Breaking down organic matter
3. Producing oxygen
4. Fixing nitrogen
Answer:
2. Breaking down organic matter

Question 47.
Humus serves as a nutrient reservoir because it is:
1. Rich in oxygen
2. Colloidal in nature and resistant to decomposition
3. Easily degradable
4. Water-soluble
Answer:
2. Colloidal in nature and resistant to decomposition

Question 48.
The decomposition rate in an ecosystem is strongly influenced by:
1. Population density
2. Chemical composition of detritus
3. Light intensity
4. Wind speed
Answer:
2. Chemical composition of detritus

Question 49.
Lignin-rich detritus decomposes slowly because:
1. It absorbs oxygen
2. It resists microbial degradation
3. It contains excess nitrogen
4. It is water-soluble
Answer:
2. It resists microbial degradation

Question 50.
In terrestrial ecosystems, energy primarily moves through the:
1. Food web
2. Detritus food chain
3. Grazing food chain
4. Pyramid of energy
Answer:
2. Detritus food chain

Question 51.
Grazing food chains dominate aquatic ecosystems because:
1. Consumers are few
2. Producers are directly consumed by herbivores
3. Decomposers are absent
4. Detritus is abundant
Answer:
2. Producers are directly consumed by herbivores

Question 52.
The number of trophic levels remains limited because:
1. Consumers are few
2. Energy is lost at each transfer
3. Biomass increases upward
4. Producers are limited
Answer:
2. Energy is lost at each transfer

Question 53.
A pyramid of numbers may become inverted when:
1. Energy flow increases
2. A single large producer supports many consumers
3. Small producers support fewer consumers
4. Decomposers dominate
Answer:
2. A single large producer supports many consumers

Question 54.
The biomass pyramid in aquatic ecosystems is inverted because:
1. Producers have high biomass
2. Consumers reproduce slowly
3. Producers have low standing biomass but high turnover
4. Energy flow is reversed
Answer:
3. Producers have low standing biomass but high turnover

Question 55.
The pyramid of energy always remains upright due to:
1. Increased biomass
2. Energy recycling
3. Loss of energy as heat at each trophic level
4. Constant energy supply
Answer:
3. Loss of energy as heat at each trophic level

Question 56.
Saprotrophs play a major role in ecosystems because they:
1. Consume producers
2. Recycle nutrients by decomposition
3. Produce organic matter
4. Fix nitrogen
Answer:
2. Recycle nutrients by decomposition

Question 57.
Ecological pyramids have limitations because they:
1. Show decomposition
2. Do not account for food webs
3. Include all organisms
4. Show exact biomass
Answer:
2. Do not account for food webs

Question 58.
Why are decomposers generally excluded from ecological pyramids?
1. They do not consume energy
2. They are absent in ecosystems
3. They operate across multiple trophic levels
4. They are autotrophs
Answer:
3. They operate across multiple trophic levels

Question 59.
Biomass is usually expressed as dry weight instead of fresh weight because:
1. Dry weight is easier to measure
2. Water content varies greatly among organisms
3. Water is insignificant
4. Dry weight is higher
Answer:
2. Water content varies greatly among organisms

Question 60.
Energy flow in ecosystems is said to be irreversible mainly because:
1. Producers dominate
2. Nutrients are reused
3. Energy dissipates as heat
4. Energy cycles continuously
Answer:
3. Energy dissipates as heat

Question 61.
If energy transfer efficiency between trophic levels increased greatly, what would happen to the number of trophic levels?
1. Remain unchanged
2. Increase as more energy becomes available
3. Become zero
4. Decrease due to instability
Answer:
2. Increase as more energy becomes available

Question 62.
Excessive accumulation of detritus in an ecosystem suggests that:
1. Mineralisation is rapid
2. Catabolism is enhanced
3. Decomposition rate is reduced
4. Fragmentation is high
Answer:
3. Decomposition rate is reduced

Question 63.
An increase in lignin content of plant litter would cause nutrient cycling to:
1. Remain unaffected
2. Become irregular
3. Decrease due to slow decomposition
4. Increase rapidly
Answer:
3. Decrease due to slow decomposition

Question 64.
The greatest energy loss in an ecosystem occurs through:
1. Food web formation
2. Nutrient cycling
3. Respiration at each trophic level
4. Photosynthesis
Answer:
3. Respiration at each trophic level

Question 65.
What is the Immediate effect of completely removing herbivores from a grazing food chain?
1. Collapse of decomposers
2. Increase in carnivores
3. Increase in plant biomass
4. Decrease in producers
Answer:
3. Increase in plant biomass

Question 66.
Secondary consumers obtain energy indirectly from producers through:
1. Parasites
2. Herbivores
3. Decomposers
4. Detritus
Answer:
2. Herbivores

Question 67.
Long food chains are uncommon in nature primarily because :
1. Producers are limited
2. Decomposers are absent
3. Energy loss increases with each transfer
4. Consumers dominate
Answer:
3. Energy loss increases with each transfer

Question 68.
A highly productive ecosystem is typically characterized by:
1. Reduced nutrient cycling
2. Low biodiversity
3. High rate of biomass production
4. Low energy flow
Answer:
3. High rate of biomass production

Question 69.
A noticeable decrease in temperature within an ecosystem is most likely to result in:
1. Increased productivity
2. Faster decomposition
3. Increased mineralisation
4. Slower decomposition
Answer:
4. Slower decomposition

Question 70.
A detritus-based ecosystem becomes dominant when:
1. Consumers dominate
2. Dead organic matter accumulation is high
3. Producers are absent
4. Live plant consumption is high
Answer:
2. Dead organic matter accumulation is high

Question 71.
Ecological pyramids do not accurately represent omnivores because they:
1. Are producers
2. Occupy multiple trophic levels simultaneously
3. Consume plants
4. Decompose matter
Answer:
2. Occupy multiple trophic levels simultaneously

Question 72.
If trophic-level energy transfer were 100%, ecosystems would theoretically:
1. Support infinite trophic levels
2. Stop functioning
3. Collapse
4. Lose energy rapidly
Answer:
1. Support infinite trophic levels

Question 73.
Multiple feeding links within a food web help in:
1. Reduced biomass
2. Energy loss
3. Greater ecosystem resilience
4. Reduced productivity
Answer:
3. Greater ecosystem resilience

Question 74.
Elimination of top carnivores from an ecosystem is most likely to cause:
1. No change
2. Increase in herbivore population
3. Stable system
4. Decrease in producers
Answer:
2. Increase in herbivore population

Question 75.
The primary reason for the inverted biomass pyramid in aquatic ecosystems is:
1. Absence of decomposers
2. Rapid turnover of phytoplankton
3. High producer biomass
4. Low consumer population
Answer:
2. Rapid turnover of phytoplankton

Reviewing AP Inter 2nd Year Botany Study Material Chapter 5 Biotechnology Principles, Processes and Applications Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Botany 5th Lesson Biotechnology Principles, Processes and Applications Questions and Answers

IV. Very Short Answer Questions

Question 1.
Define biotechnology.
Answer:
Biotechnology is a branch of science that makes use of microorganisms, living cells, or their components at an
industrial level to produce useful products and services that benefit human fife and welfare.

Question 2.
What are molecular scissors? Where are they obtained from?
Answer:

1. Molecular scissors refer to restriction enzymes that cut DNA at specific recognition sites.
2. These enzymes are naturally isolated from bacteria.

Question 3.
What is EcoRI? How does it function?
Answer:

1. EcoRI is a restriction endonuclease obtained from the bacterium Escherichia coli.
2. It recognizes the specific DNA sequence 5′ GAATTC 3′ and cleaves the DNA between G and A.

Question 4.
What are cloning vectors? Give an example.
Answer:
1. Cloning vectors are DNA molecules used to carry and multiply foreign DNA fragments inside a host cell.
2. Examples include plasmids, bacteriophages, cosmids, and artificial chromosomes.

Question 5.
What is recombinant DNA?
Answer:
Recombinant DNA (rDNA) is a hybrid DNA molecule formed by joining a desired DNA fragment with another DNA molecule using the enzyme DNA ligase.

Question 6.
What is the full form of PCR? How is it useful in biotechnology? [AP MAR-23,25]
Answer:
1- PCR stands for Polymerase Chain Reaction.
2. PCR is widely used in:

• DNA cloning
• Gene amplification
• DNA fingerprinting

Question 7.
What is downstream processing? [AP MAR-17,19]
Answer:
The process of separating, purifying, and preparing a product for commercial use after its production is known as downstream processing.

Question 8.
How can one visualize DNA on an Agar gel? [AP MAR-15,20]
Answer:
DNA fragments separated on agarose gel can be visualized by staining them with ethidium bromide and then exposing the gel to ultraviolet (UV) light.

Question 9.
How can you differentiate exonucleases from endonucleases? [AP MAR-24]
Answer:

1. Exonucleases: Remove nucleotides one by one from the ends of DNA molecules.
2. Endonucleases: Cut DNA internally at specific sites within the DNA strand.

Question 10.
Write any two beneficial aspects of Genetically Modified plants.
Answer:

1. Reduced use of pesticides: Genetically modified plants can be made resistant to insect pests, thereby reducing the need for chemical pesticides. Example: Bt crops.
2. Improved nutritional quality: Genetic modification can enhance the nutritional value of crops. Example: Golden Rice enriched with Vitamin A (β-carotene).

V. Short Answer Questions

Question 1.
Give brief account of amplification of gene of interest using PCR.
Answer:

1. PCR stands for Polymerase Chain Reaction.
2. It is a technique used to produce a large number of copies of a desired DNA segment in vitro.
3. The process requires two sets of primers (short synthetic oligonucleotides complementary to specific regions of DNA), DNA polymerase enzyme, free nucleotides, and template DNA.
4. During PCR, primers bind to the target DNA sequence, and DNA polymerase synthesizes new DNA strands using the available nucleotides and the original DNA as a template.
5. Repeated cycles of DNA replication result in exponential amplification of the target DNA. After several cycles, millions to billions of copies of the desired DNA fragment can be produced.
6. This amplification is made possible by the use ofa thermostable DNA polymerase, such as Taq polymerase, isolated from the bacterium Thermus aquaticus. This enzyme remains active even at the high temperatures required during the process.
7. The amplified DNA fragment can then be inserted into a suitable vector for cloning or used for various molecular biology applications.
8. PCR-based gene amplification is also widely used in DNA fingerprinting, where DNA fragment patterns are analyzed for identification purposes.

Question 2.
What is a bioreactor? Describe briefly the stirring type of bioreactor?
Answer:

1. Bioreactors are large vessels, generally having a capacity of 100-1000 litres, used for carrying out biological processes on a large scale.
2. In these vessels, raw materials are converted into used products such as enzymes, antibiotics, vaccines, and other biomolecules with the help of microorganisms, plant cells or animal cells.
3. A bioreactor provides ideal conditions required for maximum product formation, such as optimum temperature, pH, substrate concentration, salts, vitamins, and oxygen supply.
4. The stirred-tank bioreactor is usually cylindrical in shape and is designed to ensure proper mixing of the contents.
5. Continuous stirring helps in uniform distribution of nutrients and efficient oxygen supply throughout the culture medium.

6. A stirred-tank bioreactor generally consists of:

• Agitator (stirring) system
• Oxygen delivery system
• Foam control system
• Temperature regulation system
• pH monitoring and control system
• Sampling outlet for withdrawing small quantities of culture at regular intervals.

Question 3.
Discuss different methods of insertion of recombinant DNA into the Host cell?
Answer:
1. Introduction through competent cells: Recombinant DNA can be introduced into competent bacterial cells by keeping them on ice, exposing them briefly to 42°C (heat shock), and then returning them to ice. This facilitates uptake of recombinant DNA.

2. Microinjection Method: In this method, recombinant DNA is directly injected into the nucleus of an animal cell using fine microscopic needles called microneedles.

3. Gene Gun (Biolistic) Method: This technique is mainly used for plant cells. Tiny particles of gold or tungsten coated with DNA are fired into cells at high velocity to deliver the recombinant DNA.

4. Vector-Mediated Transfer: Disarmed pathogens are used as vectors. When these vectors infect host cells, they transfer the recombinant DNA into the host cell where it can be expressed.

Question 4.
Write a short note on Bt cotton. [Ap MAR – 25]
Answer:

1. Bt cotton is a genetically modified (GM) cotton variety developed to provide protection against insect pests, particularly bollworms.
2. It is produced by introducing specific genes obtained from the bacterium Bacillus thuringiensis (Bt) into cotton plants.
3. This bacterium synthesizes insecticidal proteins that are effective against several groups of insects, including Lepidopterans (tobacco budworm, bollworm, armyworm), Coleopterans (beetles) and Dipterans (flies and mosquitoes).
4. During a particular stage of bacterial growth, Bt produces protein crystals that contain a toxic insecticidal protein.
5. The Bt toxin is initially present in an inactive form known as a protoxin. When an insect feeds on the plant, the alkaline pH of its gut converts the protoxin into an active toxin.
6. Most Bt toxins are specific to particular insect groups. These toxins are encoded by Cry genes. For example, Cry IAc and Cry IIAb provide resistance against cotton bollworm, while Cry IAb is effective against corn borer.

Question 5.
Explain the process of RNA interference.
Answer:
RNA interference (RNAi) is a natural biological mechanism in eukaryotic organisms that functions as a cellular defence system. It suppresses the expression of a specific gene by preventing the corresponding mRNA from producing a protein.

Steps involved :

• Entry of dsRNA: The process begins when double-stranded RNA (dsRNA) enters the cell. This dsRNA is complementary to the target mRNA and may originate from viruses, transposons or experimental introduction.
• Formation of complementary RNA strands: In biotechnology, genes are introduced in such a way that both sense RNA and antisense RNA are produced. These complementary strands pair with each other to form dsRNA.
• Activation of the RNAi pathway: The dsRNA activates the RNA interference machinery, which cuts the dsRNA into small RNA fragments. These fragments help identify and target the matching mRNA molecule.
• Silencing of mRNA: The target mRNA is cleaved or degraded, preventing it from being translated into a protein.
• Protection of the host organism: Since the harmful protein is not produced, disease- causing organisms such as the nematode Meloidogyne incognita are unable to survive effectively. This protects the host plant from infection and damage.

VI. Long Answer Questions

Question 1.
Explain briefly the various processes of Recombinant DNA Technology. [AP MAR-16,17,24,25]
Answer:
Steps involved in Recombinant DNA Technology :
1. Isolation of DNA:

• DNA serves as the hereditary material in living organisms.
• It is enclosed within the cell and surrounded by various cellular components.
• Cell walls are broken down using enzymes such as lysozyme and cellulase to release cellular contents.
• Membranes, proteins, and RNA are removed with the help of detergents and enzymes like ribonuclease.
• Pure DNA is finally precipitated by adding ethanol.

2. Fragmentation of DNA: The purified DNA is cut into smaller fragments using restriction enzymes. This produces DNA pieces of different lengths.
3. Isolation of Desired DNA Fragment: The required DNA fragments are separated using agarose gel electrophoresis. Since DNA carries a negative charge, it migrates through the gel, and the desired fragment is recovered from the gel.
4. Amplification of the Desired Gene by PCR: In Polymerase Chain Reaction (PCR), numerous copies of the selected DNA fragment are produced in vitro using primers and DNA polymerase. Repeated cycles generate millions to billions of copies.

5. Ligation of the DNA Fragment into a Vector: This step requires both a vector DNA and the desired DNA fragment.

• The vector and source DNA are cut using the same restriction enzyme to generate compatible sticky ends.
• The desired gene is then joined to the vector with the help of DNA ligase, resulting in the formation of recombinant DNA

6. Introduction of rDNA into the Host Cell: Recombinant DNA can be introduced into host cells through different methods.

• Host cells can be made competent and exposed to recombinant DNA under suitable conditions to facilitate uptake.
• In microinjection, recombinant DNA is directly injected into the nucleus of an animal cell.
• In the gene gun (biolistic) method, DNA-coated gold or tungsten particles are fired into plant cells.

7. Production of the Desired Gene Product: Once recombinant DNA enters a cloning vector and host cell, the foreign DNA replicates and expresses itself, producing the required product.

8. Downstream Processing: After biosynthesis is complete, the product undergoes processing before commercial use. This includes separation, purification, and formulation of the final product.

Question 2.
Give a brief account of the tools of Recombinant DNA Technology.
Answer:
Tools of Recombinant DNA Technology: The major tools used in recombinant DNA technology are:
1. Restriction Enzymes
2. Polymerase Enzymes
3. Ligases
4. Vectors
5. Host Organisms

1. Restriction Enzymes: Restriction enzymes belong to a broader group of enzymes called nucleases.

• Exonucleases: These enzymes remove nucleotides sequentially from the ends of DNA molecules.
• Endonucleases: These enzymes cleave DNA at specific internal recognition sites. Each restriction endonuclease identifies a particular palindromic sequence.

Example: EcoRI recognizes the sequence 51 GAATTC 3′ and cuts between G and A.
5′ G A A T T C 3′
3′ C T T A A G 5′

2. Polymerase Enzymes:

• DNA polymerase is used in PCR to synthesize multiple copies of a target DNA sequence.
• Through repeated cycles, a very large number of DNA copies can be produced.
• Amplification is carried out using Taq polymerase, which remains active even at high temperatures.
• The amplified DNA fragment can subsequently be inserted into a vector for cloning.

3. Ligases :

• DNA ligase joins the ends of vector DNA and the desired DNA fragment through covalent bonds.
• This results in the formation of a circular recombinant DNA molecule.

4. Vectors: Vectors are DNA molecules that carry foreign DNA into a suitable host cell.

• Function: They help in the multiplication and maintenance of foreign DNA.
• Examples: Plasmids, Bacteriophages, Cosmids

Properties of Cloning Vectors:

• They should possess a relatively low molecular weight.
• They must contain one or more unique restriction sites.
• They should be capable of autonomous replication inside the host cell.
• They should possess a selectable marker for identifying transformed cells.

5. Host Organisms: A suitable and competent host organism is essential for the successful introduction, replication, and expression of recombinant DNA.

I. Multiple Choice Questions

Question 1.
Being a negatively charged molecule, DNA in Electrophoresis moves towards
1. Anode
2. Cathode
3. Equator
4. None of the above
Answer:
1. Anode

Question 2.
Which of the following are used in gene cloning?
1. Ribosomes
2. Plasmids
3. Mesosomes
4. Histones
Answer:
2. Plasmids

Question 3.
What is the function of restriction enzymes? ‘
1. Restrict the elongation of DNA
2. Amplify the DNA molecules
3. Cut the DNA at specific locations
4. Separate the DNA fragments based on length
Answer:
3. Cut the DNA at specific locations

Question 4.
Agarose extracted from the seaweeds is used in
1. Downstream Processing
2. DNA Isolation
3. PCR
4. Electrophoresis
Answer:
4. Electrophoresis

Question 5.
Which of following bacterium is used for production of transgenic plants
1. Agrobacterium
2. Staphylococcus
3. Pseudomonas
4. Thiobacillus
Answer:
1. Agrobacterium

Question 6.
In genetic engineering, antibiotic resistance gene is used as
1. PCR
2. Selectable marker
3. Replicator
4. Vector
Answer:
2. Selectable marker

Question 7.
The technique of producing large number of plants in a very short time is known as
1. Gene transfer
2. Conventional bree
3. Micropropagation
4. Somatic Hybridisation
Answer:
3. Micropropagation

Question 8.
Somatic hybrids are formed by
1. Meristem Culture
2. RNA interference
3. Microinjection
4. Protoplast fusion
Answer:
4. Protoplast fusion

Question 9.
Which part of the plant is grown in vitro to obtain virus-free plants
1. Meristem
2. Ovule
3. Anther
4. Leaf
Answer:
1. Meristem

Question 10.
Meloidogyne incognita, which infects the roots of a tobacco plant, is a
1. Bacterium
2. Virus
3. Algae
4. Nematode
Answer:
4. Nematode

II. Fill in the Blanks

1. Large volume of culture can be processed by using ………………………. .
Answer:
Bioreactors.

2. Genes are located on long molecules ……………………….. of intertwined with histone proteins.
Answer:
DNA

3. ……………………., in animal cells have the ability to transform normal cells into cancerous cells.
Answer:
Retrovirus

4. The separated bands of DNA are cut out from the agarose gel and extracted from gel piece. This step is known as …………………………………. .
Answer:
Elution.

5. Restriction enzymes belong to a larger class of enzymes called ……………………… .
Answer:
Nucleases.

6. Inactive Bt toxin is converted into an active form due to the ……………………… pH of the insect’s gut.
Answer:
Alkaline.

7. Cells in continuous culture system are maintained in ………………………… phase of growth.
Answer:
Log / Exponential

8. Golden rice is a genetically modified crop enriched with ………………………………….. .
Answer:
Vitamin A

9. The inherent capacity of a plant cell to produce a whole plant is known as ………………………. .
Answer:
Totipotency.

III. One Word Answer Questions

Question 1.
After 10 PCR cycles, how many DNA molecules are formed from one DNA molecule?
Answer:
1024

Question 2.
In plants, which enzyme is used to dissolve cell wall during DNA isolation?
Answer:
Cellulase

Question 3.
Agarose is a natural polymer and is extracted from? ,
Answer:
Seaweeds

Question 4.
What do you call a group of letters that form the same word when read in both forward and backward directions?
Answer:
Palindromic sequence

Question 5.
Which enzyme is commonly used-to join DNA fragments?
Answer:
DNA ligase

Question 6.
Name the plasmid extracted from Agrobacterium and used to deliver the gene of interest into a variety of dicot plants?
Answer:
Ti Plasmid

Question 7.
Which sequence is responsible for controlling the copy number of the linked DNA?
Answer:
Origin of Replication (Ori)

Question 8.
Any part of the plant used to culture in vitro to obtain plantlets is known as?
Answer:
Explant

Question 9.
What do you call the plants that are genetically identical to the original plant from which they were grown?
Answer:
Somaclones

Objective Questions

Question 1.
Restriction enzymes are commonly referred to as
1. Antibiotics
2. Chromosomes
3. Restriction enzymes
4. Genes
Answer:
3. Restriction enzymes

Question 2.
The carrier used to introduce foreign DNA into a host organism is
1. r-DNA
2. Messenger RNA
3. Plasmid
4. Chromosome
Answer:
3. Plasmid

Question 3.
Which enzymes cut DNA strands at specific recognition sites?
1. Ligases
2. Exonucleases
3. Endonucleases
4. Polymerases
Answer:
2. Exonucleases

Question 4.
A palindromic sequence in DNA
1. Serves as the recognition site for restriction enzymes
2. Functions as a plasmid
3. Acts as a vector
4. Represents the origin of replication
Answer:
1. Serves as the recognition site for restriction enzymes

Question 5.
Polymerase Chain Reaction (PCR) is mainly employed for
1. DNA precipitation
2. Gene amplification
3. Cutting DNA with restriction enzymes
4. Isolation of a desired gene
Answer:
2. Gene amplification

Question 6.
In the naming of restriction enzymes, the first letter denotes
1. Species
2. Order of isolation
3. Name of the strain
4. Genus
Answer:
4. Genus

Question 7.
Which of the following represents recombinant (chimeric) DNA?
1. Plasmid DNA
2. rDNA
3. Gene of interest after cutting
4. Primer
Answer:
2. rDNA

Question 8.
Which technique is extensively used in DNA fingerprinting?
1. Restriction digestion
2. Isolation of desired genes
3. Gene amplification
4. Extraction of DNA from agarose gel
Answer:
3. Gene amplification

Question 9.
Introduction of a DNA fragment into a bacterial host cell is known as
1. Translation
2. Transformation
3. Transcription
4. Transduction
Answer:
2. Transformation

Question 10.
DNA fragments stained after electrophoresis appear as
1. Fine crystal clusters
2. Thread-like structures
3. Bright violet bands
4. Bright orange bands
Answer:
4. Bright orange bands

Question 11.
The initial step in recombinant DNA technology is
1. Insertion of gene into vector
2. Selection of transformed cells
3. Isolation of the desired gene
4. Ligation of gene with vector
Answer:
3. Isolation of the desired gene

Question 12.
The major enzyme involved in DNA replication in E. coli is
1. DNA-dependent DNA polymerase
2. Restriction endonuclease
3. Ligase
4. DNA-dependent RNA polymerase
Answer:
1. DNA-dependent DNA polymerase

Question 13.
The chief enzyme responsible for PCR is
1. DNA ligase
2. Restriction enzyme
3. Taq polymerase
4. Hydrolase
Answer:
3. Taq polymerase

Question 14.
A commonly used vector for producing transgenic organisms is
1. Ti plasmid
2. Cos sites
3. pBR322
4. Coliphage lambda
Answer:
1. Ti plasmid

Question 15.
pUC101 belongs to the category of
1. Virus
2. Mutagen
3. Plasmid
4. Cosmid
Answer:
3. Plasmid

Question 16.
The first recombinant DNA molecule was constructed using the plasmid of
1. E. coli
2. Bacillus thuringiensis
3. Yeast
4. Salmonella typhimurium
Answer:
4. Salmonella typhimurium

Question 17.
Which among the following are known as molecular scissors?
1. Hind III
2. Bam I
3. EcoRI
4. All of these
Answer:
4. All of these

Question 18.
A labelled nucleic acid fragment used to detect a specific gene is called
1. DNA probe
2. Plasmid DNA
3. T-DNA
4. cDNA
Answer:
1. DNA probe

Question 19.
The enzyme that cuts host DNA during the restriction-modification system in E. coli is
1. Restriction exonuclease
2. Plasmid
3. Restriction endonuclease
4. Type III restriction enzyme
Answer:
3. Restriction endonuclease

Question 20.
EcoRI digestion produces the sticky end sequence
1. AATTC
2. TTAA
3. GAATTC
4. CTTAA
Answer:
2. TTAA

Question 21.
Which gene transfer method is most suitable for animal cells?
1. Gene gun method
2. Calcium-mediated uptake
3. Microinjection
4. Electroporation
Answer:
3. Microinjection

Question 22.
The ‘rop’ gene present in plasmids is associated with
1. Cloning site
2. Replication site
3. Selectable marker
4. Proteins involved in replication
Answer:
4. Proteins involved in replication

Question 23.
A nucleic acid probe tagged with a radioactive molecule can be
1. Double-stranded DNA only
2. Single-stranded RNA only
3. Single-stranded DNA only
4. Both single-stranded DNA and RNA
Answer:
4. Both single-stranded DNA and RNA

Question 24.
Which of the following is NOT required for PCR?
1. DNA template
2. Helicase enzyme
3. Oligonucleotide primer
4. Taq polymerase
Answer:
2. Helicase enzyme

Question 25.
The matrix most commonly employed in gel electrophoresis is
1. Ethidium bromide
2. Sulphite bromide
3. Agarose
4. Sulphate bromide
Answer:
3. Agarose

Question 26.
Which of the following can serve as the recognition site for EcoRI?
1. AATCT
2. GAATTC
3. ATCATC
4. ATGCAT
Answer:
2. GAATTC

Question 27.
After six PCR cycles, the number of DNA molecules produced is
1. 64
2. 16
3. 4
4. 32
Answer:
1. 64

Question 28.
If foreign DNA is inserted into the Sail site of pBR322, transformants can grow on
1. Ampicillin
2. Both antibiotics
3. Tetracycline
4. None
Answer:
1. Ampicillin

Question 29.
Which vector is commonly used to transfer genes into animal cells?
1. Ti plasmid
2.E. coli
3. Retroviruses
4. Disarmed retroviruses
Answer:
4. Disarmed retroviruses

Question 30.
The ratio of triple hydrogen-bonded to double hydrogen-bonded base pairs in an EcoRI recognition site is
1. 2: 1
2. 1: 2
3. 3: 2
4. 3: 4
Answer:
2. 1: 2

Question 31.
The Ti plasmid used for developing transgenic plants is obtained from
1. Rhizobium
2. Yeast plasmid
3. Agrobacterium
4. Azotobacter
Answer:
3. Agrobacterium

Question 32.
Identify the incorrectly matched pair
1. Restriction endonuclease – PstI
2. Retroviruses – T-DNA
3. Recognition sequence of EcoRI – 5′ GAATTC 3′
4. Plasmid – Ringlet of DNA
Answer:
2. Retroviruses – T-DNA

Question 33.
The thermostable DNA polymerase used in PCR is isolated from
1. Beggiatoa
2. Thiobacillus
3. Thermus aquaticus
4. Thermobacter
Answer:
3. Thermus aquaticus

Question 34.
Gene amplification using primers is carried out by
1. ELISA
2. Polymerase Chain Reaction
3. Gene gun
4. Microinjection
Answer:
2. Polymerase Chain Reaction

Question 35.
An antibiotic resistance gene in a vector is mainly used for selecting
1. Recombinant cells
2. Transformed cells
3. Competent cells
4. None of these
Answer:
2. Transformed cells

Question 36.
Gene-specific probes are employed in
1. Colony isolation
2. Colony identification
3. Colony hybridization
4. Colony hybridization
Answer:
3. Colony hybridization

Question 37.
DNA fragments generated by the same restriction enzyme can be joined together using
1. DNA polymerase
2. Restriction enzyme
3. DNA ligase
4. E. coli
Answer:
3. DNA ligase

Question 38.
If nitrogen bases are randomly distributed, the minimum number of nucleotides required for the sequence GAATTC to appear once is
1. 256
2. 512
3. 1024
4. 4096
Answer:
2. 512

Question 39.
The most essential feature of a plasmid is
1. Selectable marker
2. Restriction sites
3. Origin of replication (ori)
4. All of these
Answer:
3. Origin of replication (ori)

Question 40.
In genetic engineering, antibiotics are mainly used as
1. Selectable markers
2. Sources of replication
3. Culture-protecting agents
4. Healthy vector selectors
Answer:
1. Selectable markers

Question 41.
PCR primarily functions in
1. Translation
2. DNA amplification
3. Transduction
4. None of these
Answer:
2. DNA amplification

Question 42.
While cutting DNA, molecular scissors cleave
1. Phosphodiester bonds only
2. Hydrogen bonds only
3. Both phosphodiester and hydrogen bonds
4. Hydrogen and peptide bonds
Answer:
3. Both phosphodiester and hydrogen bonds

43. Agarose gel is
1. A natural polymer obtained from seaweeds
2. A natural polymer from fungi
3. A synthetic polymer from red algae
4. An artificial polymer
Answer:
1. A natural polymer obtained from seaweeds

Question 44.
Which primers are used to initiate PCR?
1. RNA primers
2. DNA primers
3. Both DNA and RNA primers
4. None of these
Answer:
1. RNA primers

Question 45.
The ori sequence in a plasmid refers to
1. The site from which replication begins
2. A sequence controlling copy number
3. A restriction site
4. Both (1) and (2)
Answer:
4. Both (1) and (2)

Reviewing AP Inter 2nd Year Botany Study Material Chapter 4 Microbes in Human Welfare Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Botany 4th Lesson Microbes in Human Welfare Questions and Answers

IV. Very Short Answer Questions

Question 1.
Why does Swiss cheese have big holes? Name the bacteria responsible for it.
Answer:

1. The large holes seen in Swiss cheese are formed due to the release of significant amounts of carbon dioxide (CO₂) during fermentation.
2. The bacterium Propionibacterium sharmanii is responsible for producing these holes.

Question 2.
What are fermentors?(AP MAY-17, 22)
Answer:
Fermentors are large-scale containers used for the commercial production of beverages, antibiotics, and other microbial products.

Question 3.
Name any two industrially important enzymes. (AP Mar-19)(AP Mar-17,19, 22)
Answer:
Examples of industrially important enzymes are: Amylase, Lipase, Streptokinase.

Question 4.
What are Baculoviruses?
Answer:

1. Baculoviruses are viruses that specifically infect insects and other arthropods.
2. They are widely used as biological control agents, and most belong to the genus Nucleopolyhedrovirus.

Question 5.
Which group of bacteria is found in both the rumen of cattle and sludge of sewage treatment plants?
Answer:
Methanogens.

Question 6.
Name the scientists who were credited with showing the role of penicillin as an antibiotic.
Answer:

1. Alexander Fleming discovered penicillin.
2. Ernst Chain and Howard Florey demonstrated and established its effectiveness as an antibiotic.

Question 7.
Name any one species of fungi used in the production of antibiotics.
Answer:

1. A fungus commonly used in antibiotic production is Penicillium notatum.
2. It is the source of the antibiotic Penicillin.

Question 8.
What is sewage? In what way can sewage be harmful to us?
Answer:
Sewage refers to municipal wastewater, which contains human excreta, organic matter, and numerous microorganisms.

1. Many of these microorganisms may be disease-causing pathogens. Therefore, sewage should not be discharged directly into rivers, lakes, or other natural water bodies without treatment.
2. Before disposal, it is treated in sewage treatment plants (STPs) using naturally occurring heterotrophic microbes.
3. If untreated sewage contaminates drinking water sources, it can spread diseases and create health problems in humans and domestic animals.

Question 9.
What is the key difference between primary and secondary sewage treatment?
Answer:

1. Primary Sewage Treatment: It is a physical process that removes suspended particles through methods such as filtration and sedimentation. It is relatively simple and less costly.
2. Secondary Sewage Treatment: It is a biological process in which the primary effluent is transferred to aeration tanks where microorganisms degrade organic matter. This method is comparatively more complex, time-consuming, and expensive.

Question 10.
How do biofertilizers enrich the fertility of the soil?
Answer:
Biofertilizers improve soil fertility through the action of living organisms such as bacteria, fungi, and cyanobacteria that enhance soil nutrient availability.

They increase soil fertility through the following processes :

1. Nitrogen fixation
2. Phosphate solubilization
3. Addition of organic matter to the soil.

V. Short Answer Questions

Question 1.
Why are floes important in the biological treatment of waste water?
Answer:
Floes are clusters of aerobic bacteria associated with fungal filaments, forming mesh-like aggregates.
Role of floes in biological treatment:

1. The primary effluent is transferred into large aeration tanks, where air is continuously supplied, and the contents are mechanically agitated.
2. These conditions promote the rapid multiplication of beneficial aerobic microorganisms, resulting in the formation of flocs.
3. While growing, these microbes break down a major portion of the organic matter present in the effluent and thereby reduce its Biochemical Oxygen Demand (BOD).
4. The treated effluent is then sent to a settling tank where the bacterial flocs settle down.
5. This settled material is known as activated sludge.
6. A small portion of the activated sludge is recycled back into the aeration tank to serve as inoculum, while the remaining sludge is transferred to anaerobic sludge digesters.

Question 2.
Name the bacterium responsible for the conversion of milk into curd. Mention two benefits of curd formation.
Answer:
The bacterium responsible for converting milk into curd is Lactobacillus, a member of the group known as Lactic Acid Bacteria (LAB).

Two advantages of curd formation are:

1. Improved Nutritional Value: The process enhances the nutritional quality of milk by increasing the amount of Vitamin B₁₂.
2. Protection Against Harmful Microbes: LAB helps maintain a healthy gut environment by suppressing the growth of disease-causing microorganisms in the digestive system.

Question 3.
What is BOD? Why is it an important parameter in sewage treatment?
Answer:
BOD (Biochemical Oxygen Demand) is the quantity of oxygen required by microorganisms to decompose the organic matter present in one litre of water.

Importance in sewage treatment:

• Measure of Organic Pollution: BOD reflects the amount of biodegradable organic matter present in water.
• Indicator of Water Quality: A higher BOD value indicates greater pollution and a larger amount of organic waste.
• Useful in Biological Treatment: During secondary treatment, aerobic microbes consume organic matter and help reduce BOD.
• Assessment of Treatment Efficiency: A decrease in BOD indicates successful sewage treatment and improved water quality.

Question 4.
Define methanogens. Give one example and their role in biogas production.
Answer:
Methanogens are anaerobic microorganisms that grow on cellulosic substrates and produce methane gas along with carbon dioxide and hydrogen in the absence of oxygen. Example: Methanobacterium Role in biogas production:

• Methanogens function in anaerobic sludge digesters and decompose organic matter.
• They help break down cellulose-rich material and release biogas.
• These organisms are also present in the rumen of cattle, where they assist in cellulose digestion.
• The methane-rich biogas produced is combustible and serves as a valuable fuel for cooking and lighting.

Question 5.
Write two advantages of mycorrhizal association of plants.
Answer:
Mycorrhiza is a mutually beneficial association between the roots of higher plants and certain fungi, commonly belonging to the genus Glomus. In this association, both the plant and the fungus benefit from each other.

Advantages of mycorrhizal association :

1. Improved Nutrient Absorption: The fungal hyphae spread extensively in the soil and increase the surface area for absorption. They help the plant absorb essential minerals, especially phosphorus, from the soil and transfer them to the plant roots, thereby enhancing plant growth.
2. Increased Resistance and Better Growth: Plants associated with mycorrhiza show greater resistance to root-borne pathogens and improved tolerance to drought and salinity. As a result, the plants grow healthier and exhibit better overall development.

Question 6.
What is meant by biocontrol? Give one example of microbial biocontrol agent.
Answer:
Biocontrol refers to the use of living organisms or biological methods to manage plant diseases and’pests instead of relying on chemical pesticides.
Example of a microbial biocontrol agent: Bacillus thuringiensis (Bt)

1. It is a bacterial biocontrol agent used against butterfly caterpillars.
2. It is available as dried spores that are mixed with water and sprayed on crops.
3. When insect larvae feed on the treated plants, the toxin becomes active in their gut and kills them.
4. It specifically targets caterpillars without affecting beneficial insects

VI. Long Answer Questions

Question 1.
Describe the role of microbes in the production of household products with suitable examples.
Answer:
Microorganisms are essential components of the biosphere and occur along with plants and animals. They include bacteria, fungi, protozoa, viruses, and other microscopic forms of life. Many microbes are beneficial and are widely used in the preparation of household products through fermentation.

Important characteristics of microbes:

1. Wide Distribution: Microorganisms are found everywhere-in soil, water, air, and inside the bodies of plants and animals. They can survive even in extreme habitats such as hot springs, deep oceans, frozen regions, and highly acidic environments.
2. Microscopic Nature: Most microbes are microscopic and cannot be seen with the naked eye. However, some bacteria and fungi can be grown on nutrient media to form visible colonies for study.
3. Importance to Human Life: Although some microbes cause diseases, many are useful and play an important role in producing several everyday products.
4. Dairy Products (Curd): Microorganisms such as Lactobacillus and other Lactic Acid Bacteria (LAB) convert milk into curd. During this process, LAB produce acids that coagulate milk proteins and partially digest them. A small quantity of curd acts as a starter culture and multiplies rapidly under suitable conditions. This process also enhances the nutritional value of milk by increasing Vitamin B12 content.
5. Fermented Dough (Dosa, Idli and Bread): The batter used for preparing foods such as dosa and idli undergoes fermentation by microbes. The soft and fluffy texture develops because of the release of carbon dioxide (CO₂) gas. Similarly, bread making involves the use of baker’s yeast (Saccharomyces cerevisiae).
6. Traditional Fermented Foods and Drinks: A traditional beverage called Toddy is prepared by fermenting palm sap. Microorganisms are also used in fermenting fish, soybean, and bamboo shoots to prepare different food products.
7. Cheese Production: Microbes contribute to the manufacture of different varieties of cheese by providing characteristic texture, flavour and aroma. The holes in Swiss cheese are formed due to CO₂ produced by Propionibacterium sharmanii. Roquefort cheese develops its special flavour through the action of selected fungi.

Question 2.
Explain the steps involved in secondary sewage treatment and the role of microbes in the process.
Answer:
Secondary sewage treatment, also called biological treatment, utilizes naturally occurring microorganisms to remove organic pollutants from wastewater. Unlike primary treatment, which is mainly physical, this stage depends on microbial activity.

The process involves the following steps:
1. Aeration and Aerobic Digestion:
Process: The primary effluent is transferred into large aeration tanks where it is continuously stirred and supplied with air.
Role of Microbes: Aeration promotes the growth of aerobic microorganisms that form floes, which are aggregates of bacteria associated with fungal filaments.
Reduction of BOD: As these microbes consume organic matter, the Biochemical Oxygen Demand (BOD) of the wastewater decreases considerably.

2. Sedimentation and Activated Sludge:
Process: After BOD is reduced, the effluent is moved into a settling tank.
Role of Microbes: The microbial flocs settle at the bottom and form activated sludge. Inoculum: A small amount of activated sludge is recycled back into the aeration tank to initiate treatment of the next batch.

3. Anaerobic Sludge Digestion:
Process: The remaining activated sludge is transferred into anaerobic sludge digesters.
Role of Microbes: Anaerobic bacteria digest the bacterial and fungal biomass present in the sludge.
Biogas Formation: During digestion, gases such as methane, hydrogen sulphide and carbon dioxide are produced, collectively forming biogas.

4. Final Disposal:

• After the biological treatment is complete, the treated effluent is generally considered safe enough to be released into natural water bodies like rivers and streams.
• This microbial methodology has been the primary way of treating millions of gallons of wastewater worldwide for over a century, as no man-made technology has yet rivaled its efficiency. Thus, Secondary sewage treatment relies on microbes to remove organic pollutants, reduce BOD, and produce useful by-products like biogas, making wastewater safe for disposal.

Question 3.
Discuss the industrial applications of microbes in the production of fermented beverages, antibiotics, and bioactive molecules.
Answer:
Microorganisms are extensively employed in industries for producing fermented beverages, antibiotics, and various bioactive compounds. These products are manufactured in large fermenters under controlled environmental conditions.
1. Fermented Beverages: Yeasts are commonly used to prepare alcoholic beverages such as wine, beer, whisky, brandy and rum.

• Microbe Used: The most widely used yeast is Saccharomyces cerevisiae (brewer’s yeast).
• Process: It ferments malted cereals and fruit juices to produce ethanol.
• Products: Wine and beer are obtained without distillation, whereas whisky, brandy and rum are produced after distillation of the fermented broth.

2. Antibiotics:

• Antibiotics are microbial substances that suppress or destroy disease- causing organisms.
• Penicillin was the first antibiotic discovered by Alexander Fleming from the fungus Penicillium notatum.
• The therapeutic value of penicillin was later demonstrated by Ernst Chain and Howard Florey.
• Antibiotics have greatly reduced deaths caused by diseases such as plague, diphtheria, whooping cough, and leprosy.

3. Bioactive Molecules and Chemicals: Microorganisms are used to manufacture several organic acids, enzymes, and bioactive compounds:

Organic Acids: Examples :

• Citric acid – Aspergillus niger
• Acetic acid – Acetobacter aceti
• Butyric acid – Clostridium butylicum
• Lactic acid – Lactobacillus

Industrial Enzymes:

• Lipases – used in detergents for removing oily stains.
• Pectinases and Proteases – used in clarifying bottled fruit juices.
• Streptokinase – produced by Streptococcus and used as a ‘clot-buster’.

Bioactive Molecules:

• Cyclosporin A, produced by Trichoderma polysporum, is used as an immunosuppressant during organ transplantation.
• Statins, produced by Monascus purpureus, help lower blood cholesterol levels by inhibiting the enzyme responsible for cholesterol synthesis.

Question 4.
Explain the process of biogas production in a typical biogas plant and name the main microbes involved.
Answer:
Biogas is a gaseous fuel mainly consisting of methane (CH₄), carbon dioxide (CO₂), traces of hydrogen sulphide (H₂S), and moisture. It is generated by the anaerobic decomposition of cattle dung, domestic waste, and agricultural residues by microorganisms.

a) Biogas Production from Sludge:

1. A small amount of activated sludge is recycled back into the aeration tank as inoculum.
2. In anaerobic digesters, methanogenic bacteria digest the bacterial and fungal biomass present in the sludge.
3. During digestion, gases such as methane, carbon dioxide, and hydrogen sulphide are released, forming biogas.

b) Biogas Production from Dung:

1. A biogas plant contains a deep concrete tank in which dung slurry is collected.
2. A floating cover is placed over the slurry and rises as gas accumulates.
3. The plant has an outlet connected to pipelines for supplying biogas to nearby houses.
4. The spent slurry is removed through a separate outlet and is used as an organic fertilizer.

Main Microbes Involved: Methanogens (e.g., Methanobacterium) are the primary microorganisms responsible for biogas production.

I. Multiple Choice Questions

Question 1.
Which microbe is commonly used to convert milk into curd?
1. Acetobacter
2. Rhizobium
3. Lactobacillus
4. Clostridium
Answer:
3. Lactobacillus

Question 2.
Penicillin was discovered by :
1. Robert Koch
2. Edward Jenner
3. Louis Pasteur
4. Alexander Fleming
Answer:
4. Alexander Fleming

Question 3.
Which enzyme is used to remove blood clots in heart patients?
1. Lipase
2. Amylase
3. Streptokinase
4. Cellulase
Answer:
3. Streptokinase

Question 4.
The bacterium that produces butyric acid is:
1. Clostridium
2. Acetobacter
3. Lactobacillus
4. Azotobacter
Answer:
1. Clostridium

Question 5.
Swiss cheese holes are due to release of CO₂ produced by :
1. Propionibacterium sharmanii
2. Saccharomyces cerevisiae
3. Lactobacillus
4. Penicillium
Answer:
1. Propionibacterium sharmanii

Question 6.
Methanogens are found in :
1. Aerobic soil
2. Vinegar
3. Cold water bodies
4. Rumen of cattle
Answer:
4. Rumen of cattle

Question 7.
The fungus used to produce cyclosporin A is:
1. Penicillium notatum
2. Trichoderma polysporum
3. Aspergillus niger
4. Saccharomyces
Answer:
2. Trichoderma polysporum

Question 8.
Which of the following microbes helps in nitrogen fixation in paddy fields?
1. Acetobacter
2. Penicillium
3. Glomus
4. Nostoc
Answer:
4. Nostoc

Question 9.
The ‘clot buster’ enzyme is produced by:
1. Streptomyces
2. Streptococcus
3. Bacillus
4. Pseudomonas
Answer:
2. Streptococcus

Question 10.
Which gas is predominantly present in biogas?
1. Carbon dioxide
2. Nitrogen
3. Oxygen
4. Methane
Answer:
4. Methane

II. Fill in the Blanks

1. The microbe used for the commercial production of ethanol is ………………………. .
Answer:
Saccharomyces cerevisiae

2. The puffed-up appearance of dough is due to the production of ………………………… .
Answer:
CO₂

3. …………………………… beverages are produced without distillation.
Answer:
Wine & Beer

4. ……………………….. antibiotic was extensively used to treat American soldiers wounded in the World War II.
Answer:
Penicillin.

5. …………………………… is used in the production of Swiss cheese.
Answer:
Propionibacterium sharmanii

6. During biological treatment, microbes significantly reduce ………………………. by consuming organic matter in effluent.
Answer:
Biochemical Oxygen Demand (BOD)

7. ………………………………. is an immunosuppressive drug obtained from Trichoderma polysporum.
Answer:
Cyclosporin A

8. …………………………….. are the enzymes helpful in removing oily stains from the laundry.
Answer:
Lipases

9. ………………….. is a free-living fungus which is an effective biocontrol agent of several plant pathogens.
Answer:
Trichoderma

10. ……………………….. is an example of a methanogen.
Answer:
Methanobacterium

III. One Word Answer Questions

Question 1.
Which bacterium is responsible for the production of acetic acid?
Answer:
Acetobacter aceti

Question 2.
Name the enzyme commonly used as a ‘clot buster’ in heart attack patients.
Answer:
Streptokinase

Question 3.
Which fungus is known for producing Cyclosporin A?
Answer:
Trichoderma polysporum

Question 4.
Name the yeast that is commercially used for producing statins.
Answer:
Monascuspurpureus

Question 5.
What is the full form of BOD?
Answer:
Biochemical Oxygen Demand

Question 6.
Mention one methanogenic bacterium present in the rumen of cattle.
Answer:
Methanobacterium

Question 7.
Which bacterium acts as a biocontrol agent against butterfly caterpillars?
Answer:
Bacillus thuringiensis

Question 8.
Name a fungal genus that forms mycorrhizal associations.
Answer:
Glomus.

Question 9.
Which group of viruses is used as a biological control agent for insect pests?
Answer:
Nucleopolyhedroviruses

Question 10.
Name the traditional Indian beverage prepared by fermenting palm sap.
Answer:
Toddy

Objective Questions

Question 1.
Which bacterium is widely used in converting milk into curd?
1. Bacillus
2. Thiobacillus
3. Lactobacillus
4. Ferrobacillus
Answer:
3. Lactobacillus

Question 2.
LAB (Lactic Acid Bacteria) enhances the nutritional value of curd by increasing the amount of:
1. Vitamin B₁₂
2. Vitamin B₁
3. Vitamin B₂
4. Vitamin B₆
Answer:
1. Vitamin B₁₂

Question 3.
Bread dough fermentation is mainly carried out by:
1. Candida utilis
2. Lactobacillus
3. Saccharomyces cerevisiae
4. Candida lipolytica
Answer:
3. Saccharomyces cerevisiae

Question 4.
The batter used for preparing Idli and Dosa undergoes fermentation by:
1. Bacteria
2. Algae
3. Protozoans
4. Viruses
Answer:
1. Bacteria

Question 5.
Cheese and yoghurt are obtained through the process of:
1. Pasteurisation
2. Fermentation
3. Distillation
4. Dehydration
Answer:
2. Fermentation

Question 6.
Which acid is commonly formed during microbial fermentation?
1. Oxaloacetic acid
2. Lactic acid
3. Fumaric acid
4. Acetic acid
Answer:
2. Lactic acid

Question 7.
Who discovered Penicillin?
1. Louis Pasteur
2. Waksman
3. Alexander Fleming
4. Edward Jenner
Answer:
3. Alexander Fleming

Question 8.
Which one of the following is NOT a beverage?
1. Beer
2. Rum
3. Penicillin
4. Wine
Answer:
3. Penicillin

Question 9.
Large-scale vessels used for culturing microbes are called:
1. Sterilizers
2. Fermenters
3. Autoclaves
4. Stabilizers
Answer:
2. Fermenters

Question 10.
Which was the first antibiotic discovered?
1. Aureomycin
2. Penicillin
3. Ampicillin
4. Tetracycline
Answer:
2. Penicillin

Question 11.
Citric acid is commercially produced by:
1. Yeasts
2. Aspergillus niger
3. Penicillium notatum
4. Chaetomium cellulolyticum
Answer:
2. Aspergillus niger

Question 12.
The first artificially synthesized hormone was:
1. Inulin
2. Casein
3. Insulin
4. Collagen
Answer:
3. Insulin

Question 13.
Beer is commonly prepared from:
1. Grapes
2. Molasses
3. Barley
4. Rye
Answer:
3. Barley

Question 14.
Penicillin is obtained from:
1. Fungus
2. Virus
3. Bacterium
4. Algae
Answer:
1. Fungus

Question 15.
Select the incorrect statement regarding antibiotics:
1. Antibiotics are effective only against specific microbes
2. The first antibiotic discovered was penicillin
3. Some individuals may develop allergy to antibiotics
4. An antibiotic can cure any disease
Answer:
1. Antibiotics are effective only against specific microbes

Question 16.
Ethanol production from starch is carried out using:
1. Lactobacillus
2. Azotobacter
3. Acetobacter
4. Saccharomyces
Answer:
4. Saccharomyces

Question 17.
A vaccine is:
1. A treated bacterial, viral, or protein preparation
2. A treated phage
3. A treated alga
4. A treated fungus
Answer:
1. A treated bacterial, viral, or protein preparation

Question 18.
The term “antibiotic” was introduced by:
1. Edward Jenner
2. Waksman
3. Dr. Y. Subba Rao
4. Alexander Fleming
Answer:
2. Waksman

Question 19.
After a viral infection, infected host cells release:
1. Antibody
2. Interferon
3. Antigen
4. Interleukin
Answer:
2. Interferon

Question 20.
What is the scientific name of baker’s yeast?
1. Candida utilis
2. Saccharomyces cerevisiae
3. Candida lipolytica
4. Chaetomium cellulolyticum
Answer:
2. Saccharomyces cerevisiae

Question 21.
Statins are commercially used as:
1. Blood cholesterol-lowering agents
2. Immunosuppressive agents
3. Clot busters
4. Oil-stain removers
Answer:
1. Blood cholesterol-lowering agents

Question 22.
Which enzyme is commonly used to remove oily stains?
1. Pectinase
2. Lipase
3. Urease
4. Sucrase
Answer:
2. Lipase

Question 23.
BOD stands for:
1. Biological Oxygen Demand
2. Biogeographical Oxygen Demand
3. Biochemical Oxygen Demand
4. Biophysical Oxygen Demand
Answer:
3. Biochemical Oxygen Demand

Question 24.
The major constituent of biogas is:
1. Acetone
2. Methane
3. Ethane
4. Ammonia
Answer:
2. Methane

Question 25.
The microorganisms mainly involved in gobar gas plants are:
1. Denitrifying bacteria
2. Nitrogen-fixing bacteria
3. Methanogens
4. Nitrifying bacteria
Answer:
3. Methanogens

Question 26.
Sewage purification is carried out by:
1. Antibiotics
2. Microbes
3. Fertilizers
4. Antiseptics
Answer:
2. Microbes

Question 27.
Baculoviruses specifically infect:
1. Arthropods
2. Coelenterates
3. Annelids
4. Nematodes
Answer:
1. Arthropods

Question 28.
Which of the following is a symbiotic nitrogen-fixing bacterium?
1. Azotobacter
2. Rhizobium
3. Clostridium
4. Azospirillum
Answer:
2. Rhizobium

Question 29.
Which among the following acts as a biofertilizer?
1. Rhizobium and legume association
2. Blue-green algae and Azolla
3. Nostoc and grasses
4. E. coli and legume association
Answer:
2. Blue-green algae and Azolla

Question 30.
Farmers can enhance paddy yield by nearly 50% through the use of:
1. Rhizobium
2. Farmyard manure
3. Cyanobacteria
4. Cyanobacteria and Azolla
Answer:
4. Cyanobacteria and Azolla

Reviewing AP Inter 2nd Year Botany Study Material Chapter 3 Molecular Basis of Inheritance Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Botany 3rd Lesson Molecular Basis of Inheritance Questions and Answers

IV. Very Short Answer Questions

Question 1.
Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?
Answer:

Question 2.
Who proved that DNA is genetic material? On which organism they worked?
Answer:

1. Alfred Hershey and Martha Chase demonstrated that DNA is the genetic material.
2. They conducted their experiment using bacteriophages, which are viruses that infect bacteria.

Question 3.
What is the function of DNA polymerase?
Answer:

1. DNA polymerase is a highly efficient enzyme that catalyses the polymerisation of a large number of nucleotides within a very short period.
2. It also carries out the polymerisation process with a high level of accuracy.

Question 4.
What are the components of a nucleotide?
Answer:
A nucleotide consists of 3 components, nitrogen base, pentose sugar and phosphate group.

Question 5.
Given below is the sequence of coding strand of DNA in a transcription unit. 5′-AATGACGCCTATTAGG-3 ′. Write the sequence of
a) Its complementary strand
b) The mRNA
Answer:
a) 3 ‘TTACTGCGGATAATCC’ 5
b) 5 ‘AAUGACGCCUAUUAGG’ 3

Question 6.
Name any two viruses which have RNA as genetic material.
Answer:

1. Influenza virus
2. Polio virus
3. HIV

Question 7.
What are the components of a transcriptional unit?
Answer:
The components of transcription unit are Promoter, structural gene, and terminator.

• A promoter,
• the structural gene, and
• A Terminator.

Question 8.
What is the difference between exons and introns?
Answer:

1. Exons: These are the coding regions of a gene. They are retained in the mature (processed) RNA after RNA processing.
2. Introns: These are the non-coding regions of a gene. They are removed during RNA processing and are absent in the mature (processed) RNA.

Question 9.
What is meant by capping and tailing?
Answer:

1. Capping: The addition of a modified nucleotide, methylguanosine triphosphate (mwG), to the 52 end of hnRNA is known as capping.
2. Tailing: The addition of 200 – 300 adenylate (poly-A) residues to the 32 end of hnRNA is called tailing.

Question 10.
What is meant by point mutation? Give an example.
Answer:

1. A point mutation is a mutation that occurs due to a change in a single base pair of a DNA molecule.
2. Example: Sickle cell anaemia.

Question 11.
What is meant by charging of tRNA?
Answer:
Charging of tRNA is the process in which an amino acid is activated in the presence of ATP and then attached to its corresponding (cognate) tRNA.

Question 12.
What is the function of the codon AUG? (AP MAY-22) (AP-20)
Answer:
AUG performs two important functions:

1. It serves as the start (initiation) codon during protein synthesis.
2. It specifies the amino acid methionine.

Question 13.
What do you understand ‘Stop codon’, and mention them. (AP MAR-15,19)
Answer:

1. Stop codons are codons that signal the termination of protein synthesis.
2. The three stop codons are UAA, UAG, and UGA.
3. These codons do not specify any amino acid.

Question 14.
What is the difference between the template strand and a coding strand in a DNA molecule?
Answer:

1. During transcription, the two strands of the DNA molecule separate from each other.
2. The template strand serves as the complementary strand that guides the synthesis of mRNA.

The coding strand has the same nucleotide sequence as the mRNA (except that thymine is replaced by uracil in RNA) and does not directly serve as the template for transcription.

Question 15.
Write any two chemical differences between DNA and RNA.
Answer:

Question 16.
In a typical DNA molecule, the proportion of Thymine is 30%. Find out the percentage
Answer:

• Adenme =30%,
• Guanine = 20%,
• Cytosine = 20% (Total 70%).

Question 17.
The proportion of nucleotides in a given nucleic acid are: Adenine 18%, Guanine 30%, Cytosine 42%, and Uracil 10%. Name the nucleic acid and mention the number of strands in it.
Answer:

1. It is RNA (presence of uracil)
2. It is only single-stranded.

V. Short Answer Questions

Question 1.
Define transformation. Give a brief account of Griffith’s experiment,
Answer:

1. Transformation: Transformation is the process in which a cell undergoes a genetic change by taking up and incorporating genetic material from its surroundings through the cell membrane.
2. In 1928, Frederick Griffith performed a series of experiments on the bacterium Streptococcus pneumoniae, which causes pneumonia.
3. During his study, he observed that the bacteria could change from one form to another when grown in a culture medium.

4. He identified two strains of the bacterium:

• Smooth strain (S-type) – forms smooth colonies due to the presence of a capsule.
• Rough strain (R-type) – lacks a capsule and forms rough colonies.

5. The S-type bacteria were disease-causing (virulent), whereas the R-type bacteria were harmless (non-virulent).
6. When living S-type cells were injected into mice, the mice developed pneumonia and died.
7. When living R-type cells were injected into mice, the mice remained healthy and survived.
8. Injection of heat-killed S-type cells did not cause disease in mice.
9. However, when heat-killed S-type cells were mixed with living R-type cells and injected into mice, the mice died, and living S-type bacteria were recovered from them
10. Griffith concluded that the living R-type bacteria had been converted into S-type bacteria by some substance released from the dead S-type cells.
11. He called this substance the transforming principle, which was later identified as DNA.

Question 2.
Discuss the significance of heavy isotope of nitrogen in Meselson and Stahl’s experiment?
Answer:
In 1958, Meselson and Stahl used the heavy nitrogen isotope 15N to demonstrate that DNA replication follows a semi-conservative mode.
1. Importance of ¹⁵N:

• Labelling DNA: E. coli bacteria were grown in a medium containing ¹⁵NH₄Cl, allowing ¹⁵N to become incorporated into DNA, producing heavy DNA.
• Density Difference: Since ¹⁵N is heavier than ¹⁴N, DNA containing ¹⁵N could be easily distinguished from normal DNA based on density.
• Separation by Centrifugation: DNA samples were separated using CsCl density gradient centrifugation.
  Heavy DNA (¹⁵N) formed a lower band.
  Light DNA (¹⁴N) formed an upper band.

2. Tracking DNA Replication:
When bacteria were shifted to a medium containing ¹⁴N:
After one generation: Only hybrid DNA (intermediate density) was observed.
After two generations: Both hybrid DNA and light DNA were present in equal proportions. Proof of

Semi-Conservative Replication:
These observations proved that every newly formed DNA molecule contains:

1. One parental strand (old strand) (¹⁵N)
2. One newly synthesized strand (new strand) (¹⁴N). Thus, the use of ¹⁵N enabled scientists to trace DNA replication and provided the first experimental evidence for the semi-conservative replication of DNA.

Question 3.
How does t-RNA act as an adaptor molecule?
Answer:
t-RNA (transfer RNA), also known as soluble RNA (s-RNA), functions as an adaptor molecule because it connects the genetic information present in mRNA with the amino acids required for protein synthesis. This concept was proposed by Francis Crick.

How t-RNA Functions as an Adapter:
1. Two Functional Ends: t-RNA possesses two important binding regions:

• Anticodon loop – recognizes and binds to the complementary codon on mRNA.
• Amino acid acceptor end – attaches to a specific amino acid.

This enables t-RNA to link codons with their corresponding amino acids.

2. Specificity: Each type of t-RNA carries only a particular amino acid, ensuring accuracy during protein synthesis.
3. Charging (Aminoacylation): Before translation begins, amino acids are attached to their respective t-RNAs using ATP. This process is called charging of t-RNA or aminoacylation.
4. Structure: t-RNA has a cloverleaf-shaped secondary structure, while its three-dimensional structure resembles an inverted L-shape, which helps it function efficiently.

During Translation:

• The anticodon of t-RNA pairs with the codon on mRNA and delivers the correct amino acid to the ribosome.
• Thus, t-RNA serves as a bridge between mRNA codons and amino acids, ensuring proper synthesis of proteins.

Question 4.
How many types of RNA polymerases exist in eukaryotic cells? Write their names and functions.
Answer:
Eukaryotic cells contain three major RNA polymerases in the nucleus (apart from those present in organelles). They are:

1. RNA Polymerase I: Responsible for the synthesis of rRNA molecules (28S, 18S, and 5.8S rRNA).
2. RNA Polymerase II: Synthesizes hnRNA (heterogeneous nuclear RNA), the precursor of messenger RNA (mRNA).
3. RNA Polymerase III: Carries out the transcription of tRNA, 5S rRNA, and snRNA (small nuclear RNA).

Question 5.
Identify the A, B, C, and D in the given picture.

Answer:

• A → Transcription Unit (Structural Gene): The DNA segment located between the initiation and termination signals where transcription takes place.
• B → Promoter: The DNA region where RNA polymerase binds to initiate transcription.
• C → Coding Strand (Non-template Strand): The DNA strand whose sequence is similar to the RNA transcript, except that thymine (T) is replaced by uracil (U) in RNA.
• D → Terminator: The DNA sequence that signals the end of transcription.

Question 6.
Draw the schematic representation of Lac operon.
Answer:

Question 7.
What are the differences between DNA and RNA?
Answer:

Question 8.
Write the salient features of Genetic code? (AP Mar. 16,17, 24)
Answer:
The important characteristics of the genetic code:

1. The genetic code is a collection of instructions that guides the conversion of genetic information into proteins containing 20 amino acids.
2. It is made up of 64 nucleotide triplets, and each triplet is known as a codon.
3. Out of the 64 codons, 61 codons specify amino acids, while 3 codons do not code for any amino acid and function as stop codons.
4. Each codon specifies only one particular amino acid, making the genetic code unambiguous and specific.
5. Some amino acids are represented by more than one codon; therefore, the genetic code is said to be degenerate.
6. Codons are read continuously on mRNA without any gaps or punctuation marks, making the code comma-less.
7. The genetic code is nearly universal, meaning it functions similarly in almost all living organisms.
8. Example: The codon UUU codes for Phenylalanine (Phe) in organisms ranging from bacteria to humans.

Question 9.
Give a brief account on nucleosome with a neat labelled diagram.
Answer:

1. A nucleosome is the fundamental bead-like structural unit of chromatin.
2. It consists of a histone octamer (eight histone protein molecules) around which DNA is wrapped, along with a DNA segment of about 200 base pairs.
3. The negatively charged DNA strand coils around the positively charged histone octamer to form a nucleosome.
4. Nucleosomes help in packing and compacting DNA within the nucleus.
5. Chromatin is composed of DNA and basic histone proteins.
6. Nucleosomes are arranged repeatedly along the chromatin fibre, forming its basic repeating units.
7. Under an electron microscope, chromatin appears as a “beads-on-a-string” structure due to the presence of nucleosomes.

VI. Long Answer Questions

Question 1.
Give an account of post-transcriptional modifications of a eukaryotic mRNA.
Answer:
The primary transcript (hnRNA) undergoes several modifications after transcription inside the nucleus before becoming mature mRNA.

5′ Capping:

• The first modification is the addition of a 7-methylguanosine cap at the 5′ end of hnRNA through an unusual 5′ – 5′ triphosphate linkage.
• Extra methyl groups may also be added to the cap structure.
• The cap protects mRNA from degradation, helps in its stability, and assists in the initiation of translation.

2. Addition of Poly-A Tail:

• A long chain of about 40-200 adenine nucleotides is added to the 3′ end of mRNA.
• This structure is called the Poly-A tail.
• It is added after transcription and is not directly coded by DNA.
• The Poly-A tail improves mRNA stability and helps in its transport from the nucleus to the cytoplasm.
• As mRNA ages in the cytoplasm, the Poly-A tail gradually becomes shorter.

3. Splicing (Removal of Introns):

• Eukaryotic hnRNA contains both coding and non-coding sequences.
• The non-coding regions called introns are removed.
• The coding regions called exons are joined together to form mature mRNA.
• After these modifications, the mature mRNA leaves the nucleus and participates in protein synthesis.

Question 2.
Discuss the process of translation in detail.
Answer:
Translation is the process by which amino acids are linked together according to the sequence of codons in mRNA to form a polypeptide chain. The process occurs in three stages:

1. Initiation:

• Amino acids are first attached to their specific tRNAs using ATP (charging of tRNA).
• The start codon AUG on mRNA is recognized by the charged initiator tRNA.
• The ribosome acts as the site where translation occurs.
• It contains two binding sites for tRNA molecules.
• The small ribosomal subunit binds to mRNA at the start codon, followed by the attachment of the large subunit.

2. Elongation:

• The ribosome moves along the mRNA one codon at a time.
• Each incoming amino acid carried by tRNA is joined to the growing polypeptide chain by a peptide bond.
• This step continues repeatedly, resulting in the elongation of the protein chain.

3. Termination:

• Translation stops when the ribosome reaches a stop codon (UAA, UAG, or UGA).
• The completed polypeptide is released, and the ribosomal subunits detach from the mRNA.

Question 3.
Give the salient features of the Double helix structure of DNA.
Answer:
The Double Helix Model of DNA was proposed by Watson and Crick
1. DNA consists of two polynucleotide strands. Each strand has a sugar-phosphate backbone on the outside and nitrogenous bases projecting inward.
2. The two strands run in opposite directions (anti-parallel). If one strand runs 5′ → 3′, the other runs 3′ → 5′.
3. The nitrogenous bases pair through hydrogen bonds:

• Adenine (A) pairs with Thymine (T) by two hydrogen bonds.
• Guanine (G) pairs with Cytosine
• by three hydrogen bonds. This complementary pairing maintains a constant diameter of about 20 Å throughout the helix.

4. DNA is a right-handed helix. One complete turn measures 3.4 nm and contains about 10 base pairs. The distance between two adjacent base pairs is 0.34 nm.
5. The base pairs are stacked one above another, which provides additional stability to the DNA molecule along with hydrogen bonding.

Question 4.
Describe the Lac operon with schematic representation.
Answer:

1. The Lac operon is a group of regulatory and structural genes that function together to control the metabolism of lactose in bacteria.
2. It consists of important regions such as the regulator gene (i), promoter (P), operator (O), and three structural genes: Z, Y, and A.
3. The operon enables the utilization of lactose by converting it into simpler sugars like glucose and galactose.
4. In the Lac operon, lactose acts as an inducer.
5. When lactose is present, it binds to the repressor protein and makes it inactive. RNA polymerase can then bind to the promoter and begin transcription.
6. As a result, the structural genes Z, Y, and A are expressed and produce their respective enzymes.
7. These enzymes help in the breakdown and utilization of lactose. When lactose levels decrease, the repressor protein is produced again.
8. The active repressor binds to the operator region and blocks RNA polymerase from transcribing the operon. Therefore, transcription stops in the absence of the inducer.

Schematic representation of the Lac operon

I. Multiple Choice Questions

Question 1.
Which among the following is not true?
1. Bacteriophage Φ × 174 has 5386 nucleotides.
2. Bacteriophage lambda has 48502 bp.
3. Escherichiacolihas 4.6 × 10⁶ bp.
4. Haploid content of human DNA is 6.6 × 10⁹ bp.
Answer:
4. Haploid content of human DNA is 6.6 × 10⁹ bp.

Question 2.
As per the Watson and Crick DNA model, the pitch length of the DNA double helix is
1. 0.34 nm
2. 3.4 nm
3. 3.4 Å
4. 0.34 Å
Answer:
2. 3.4 nm

Question 3.
Which of the following nitrogen base is absent in RNA?
1. Adenine
2. Cytosine
3. Uracil
4. Thymine
Answer:
4. Thymine

Question 4.
Approximate length of a typical mammalian cell DNA is
1. 2.6 meters
2. 2 meters
3. 2.2 metres
4. 2.4 meters
Answer:
3. 2.2 metres

Question 5.
A molecule should not have one of the following features to act as a genetic material
1. It should be able to generate its replica (Replication).
2. It should be stable chemically and structurally.
3. It should provide the scope for rapid changes that are required for evolution.
4. It should be able to express itself in the form of‘Mendelian Characters’.
Answer:
3. It should provide the scope for rapid changes that are required for evolution.

Question 6.
DNA fragments can be joined by the following enzyme.
1. DNA polymerase
2. DNA Ligase
3. DNase
4. DNA-dependent RNA polymerase
Answer:
2. DNA Ligase

Question 7.
During the transcription RNA Polymerase binds to the following region of transcriptional unit.
1. Terminator
2. Structural gene
3. Promoter
4. Operator
Answer:
3. Promoter

Question 8.
What is the role of RNA polymerase III in the process of transcription in Eukaryotes?
1. Transcription of tRNA, 5 s rRNA, and snRNA
2. Transcription of precursor of mRNA
3. Transcription of only snRNAs
4. Transcription of rRNAs(28S, 18S and 5.8S)
Answer:
1. Transcription of tRNA, 5 s rRNA, and snRNA

Question 9.
‘Operon’concept was proposed by
1. Meselson and Stahl
2. Watson and Crick
3. Jacob and Monod
4. Har Gobind Khorana
Answer:
3. Jacob and Monod

Question 10.
Enzyme permease is synthesized by
1. z-gene
2. a-gene
3. i-gene
4. y-gene
Answer:
4. y-gene

II. Fill in the Blanks

1. DNA is a polymer of ………………………………….. .
Answer:
Deoxyribonucleotides.

2. Cytosine, Uracil …………………………. and are together called Pyrimidines.
Answer:
Thymine.

3. DNA was first identified by Friedrich Miescher, and he named it as ………………………….. .
Answer:
Nuclein

4. James Watson and Francis Crick …………………………… proposed model of DNA.
Answer:
Double Helix

5. Discontinuous synthesis of DNA takes place on ……………………………. parental strand of DNA.
Answer:
5’→ 3′

6. ……………………………… is loosely packed and transcriptionally active chromatin.
Answer:
Euchromatin

7. The average rate of polymerisation by DNA polymerase enzyme in E.coli is approximately …………………. per second.
Answer:
2000 bp

8. In bacterial cells, with the help of ………………………….. factor, RNA polymerase initiates transcription.
Answer:
Sigma or σ

9. During transcription, ……………………… enzyme plays a key role in DNA helix unwinding.
Answer:
RNA polymerase

10. Copying of genetic information from one strand of the DNA into RNA is termed as …………………. .
Answer:
transcription

III. One Word Answer Questions

Question 1.
Name the pyrimidine which is common in both DNA and RNA.
Answer:
Cytosine

Question 2.
Which feature of DNA molecule enables the constant distance between two strands?
Answer:
Purine and pyrimidine base pairing.

Question 3.
Who proposed central dogma in molecular biology?
Answer:
Francis Crick.

Question 4.
Write the names of basic amino acids which are rich in histone proteins.
Answer:
Lysine and arginine

Question 5.
At what specific region, DNA replication initiates?
Answer:
‘Ori’region

Question 6.
Name the bacteria which is used by Griffith for conducting transformation experiments.
Answer:
Streptococcus pneumoniae

Question 7.
Normal E. coli was allowed to grow in a medium containing ¹⁵NH₄Cl for 80 minutes; then what would be the proportions of light, hybrid, and heavy density DNA molecules?
Answer:
0: 2: 14

Question 8.
In which direction does the DNA polymerase enzyme polymerises the DNA.
Answer:
5′ → 3′

Question 9.
Write the name of Severo Ochoa enzyme.
Answer:
Polynucleotide phosphorylase

Question 10.
Who first proposed that the‘codon’is a triplet?
Answer:
George Gamow

Objective Questions

Question 1.
The basic building blocks of nucleic acids are known as
1. Nitrogen bases
2. Nucleotides
3. Pentose monosaccharides
4. Nucleosides
Answer:
2. Nucleotides

Question 2.
The genetic molecule found most abundantly in living organisms is
1. RNA
2. tRNA
3. DNA
4. mRNA
Answer:
3. DNA

Question 3.
The repeating units that make up nucleic acid chains are called
1. Nucleosides
2. Heterocyclic molecules
3. Nucleotides
4. Pentose sugars
Answer:
3. Nucleotides

Question 4.
The principal genetic material in most organisms is
1. mRNA
2. DNA
3. rRNA
4. RNA
Answer:
3. rRNA

Question 5.
DNA molecule carries a
1. Positive charge
2. No charge
3. Negative charge
4. Positive charge only during denaturation
Answer:
3. Negative charge

Question 6.
Another name for thymine is
1. Thymidylic acid
2. 5-methyluracil
3. Uridine
4. Thymidine
Answer:
2. 5-methyluracil

Question 7.
DNA acts as a template for the synthesis of
1. DNA only
2. Proteins only
3. Both DNA and RNA
4. RNA only
Answer:
3. Both DNA and RNA

Question 8.
DNA replication generally takes place during
1. Interphase
2. Meiosis
3. Mitosis
4. Interkinesis
Answer:
1. Interphase

Question 9.
RNA differs from DNA in the
1. Type of pyrimidines
2. Number of polynucleotide strands
3. Type of purines
4. Type of sugar
Answer:
3. Type of purines

Question 10.
In DNA, each sugar molecule is attached to
1. One phosphate and two nitrogen bases
2. Two phosphates and two nitrogen bases
3. Two phosphates and one nitrogen base
4. One nitrogen base and one phosphate
Answer:
3. Two phosphates and one nitrogen base

Question 11.
DNA is absent in
1. Mitochondria
2. Plasmids
3. Chloroplasts
4. Ribosomes
Answer:
4. Ribosomes

Question 14.
Which statement correctly describes a property of DNA?
1. It should evolve rapidly
2. It should be biochemically unstable
3. It should mutate very quickly
4. It should be able to replicate
Answer:
4. It should be able to replicate

Question 15.
In eukaryotes, one mRNA molecule is generally produced from
1. Three structural genes
2. A single structural gene
3. Many structural genes
4. Two structural genes
Answer:
2. A single structural gene

Question 16.
The approximate time required for DNA replication in E. coli is
1. 20 minutes
2. 40 minutes
3. 18 minutes
4. 80 minutes
Answer:
3. 18 minutes

Question 17.
The total length of DNA present in a typical human cell is about
1. 4.2 metres
2. 3.2 metres
3. 1.2 metres
4. 2 metres
Answer:
4. 2 metres

Question 18.
DNA strands are described as antiparallel because of
1. Peptide bonds
2. Hydrogen bonds
3. Phosphodiester bonds
4. Disulphide bonds
Answer:
2. Hydrogen bonds

Question 19.
One complete turn of B-form DNA measures nearly
1. 2.0 nm
2. 20 nm
3. 3.4 nm
4. 0.34 nm
Answer:
3. 3.4 nm

Question 20.
The transfer of genetic information from DNA into RNA is called
1. Polyadenylation
2. Transformation
3. Transcription
4. Translation
Answer:
3. Transcription

Question 21.
During transcription, the DNA strand that is copied is called
1. Coding strand
2. Terminator strand
3. Template strand
4. Promoter strand
Answer:
1. Coding strand

Question 22.
The DNA strand not directly used in RNA synthesis is known as
1. Template strand
2. Coding strand
3. Antisense strand
4. Complementary strand
Answer:
2. Coding strand

Question 23.
In bacteria, transcription and translation occur respectively in
1. Cytoplasm and cytoplasm
2. Nucleus and cytoplasm
3. Cytoplasm and genephore
4. Nucleoid and nucleus
Answer:
1. Cytoplasm and cytoplasm

Question 24.
Identify the incorrect match.
1. mRNA-template for protein synthesis
2. tRNA-reader of genetic code
3. rRNA – catalytic role in translation
4. Transcription – DNA-dependent DNA polymerase
Answer:
4. Transcription – DNA-dependent DNA polymerase

Question 25.
The primary transcript is longer than functional hnRNA in
1. Prokaryotic animals
2. Cyanobacteria
3. Eukaryotes
4. Prokaryotes
Answer:
3. Eukaryotes

Question 26.
Transcription of snRNA is carried out by
1. RNA polymerase II
2. RNA polymerase III
3. RNA polymerase I
4. RNA polymerase I & II
Answer:
2. RNA polymerase III

Question 27.
Introns are commonly found in
1. Eukaryotes only
2. Both prokaryotes and eukaryotes
3. Bacteria only
4. Prokaryotes only
Answer:
1. Eukaryotes only

Question 28.
Exons are present in
1. Only in prokaryotes
2. Only in eukaryotic plants
3. Both prokaryotes and eukaryotes
4. Only in eukaryotes
Answer:
4. Only in eukaryotes

Question 29.
Split genes are characteristic of
1. Cyanobacteria
2. Bacteria
3. All Monerans
4. Eukaryotes
Answer:
4. Eukaryotes

Question 30.
Genes are primarily made up of
1. Glycoproteins
2. Histone proteins
3. Polynucleotides
4. Lipoproteins
Answer:
3. Polynucleotides

Question 31.
The synthesis of repressor mRNA is controlled by
1. ‘i’ gene
2. ‘Y’ gene
3. ‘Z’ gene
4. ‘O’ gene
Answer:
1. ‘i’ gene

Question 32.
The total number of nucleotides present in bacteriophage lambda DNA is
1. 97040
2. 48520
3. 48502
4. 97004
Answer:
3. 48502

Question 33.
The transcriptionally active form of chromatin is called
1. Heterochromatin
2. Euchromatin
3. Chromatogram
4. Prochromatin
Answer:
2. Euchromatin

Question 34.
DNA is composed of which of the following?
A) Sugar
B) Phosphate
C) Purines
D) Pyrimidines
1. A, B and C only
2. A and C only
3. A, B, C and D
4. A and D only
Answer:
3. A, B, C and D

Question 35.
A nucleoside differs from a nucleotide by
1. Presence of phosphate group
2. Absence of phosphate group
3. Absence of sugar
4. Absence of nitrogen base
Answer:
2. Absence of phosphate group

Question 36.
The earliest proof that DNA acts as the genetic material came from
1. Phage infection
2. Bacterial transformation
3. Bacterial translocation
4. Transfection
Answer:
1. Phage infection

Question 37.
Griffith conducted his transformation experiment using
1. Streptococcus pyogenes
2. Escherichia coli
3. Streptococcus pneumoniae
4. Streptomyces griseus
Answer:
3. Streptococcus pneumoniae

Question 38.
Avery, MacLeod, and McCarty identified …………………….. as the transforming principle.
1. Proteins
2. Polysaccharides
3. DNA
4. RNA
Answer:
3. DNA

Question 39.
Around each histone core, DNA wraps approximately
1. Two turns
2. Five turns
3. Three turns
4. Four turns
Answer:
1. Two turns

Question 40.
Uracil differs from thymine because it
1. Has a methyl group
2. Has two C-N rings
3. Contains an NH₂ group
4. Lacks a methyl group
Answer:
4. Lacks a methyl group

Question 41.
The haploid DNA content in humans is approximately
1. 48502 bp
2. 5386 nucleotides
3. 3.3 × 10⁹ bp
4. 4.6 × 10⁶ bp
Answer:
3. 3.3 × 10⁹ bp

Question 42.
A nucleotide is composed of
1. Sugar + Phosphate
2. Base + Sugar
3. Base + Phosphate
4. Base + Sugar + Phosphate
Answer:
2. Base + Sugar

Question 43.
Which of the following is NOT a property of genetic material?
1. Self-replication
2. Chemical and structural stability
3. Fast mutation
4. Self-expression
Answer:
3. Fast mutation

Question 44.
Which statement is NOT a characteristic of RNA?
1. RNA evolves slowly
2. RNA is unstable and degradable
3. RNA can act as a catalyst
4. RNA mutates faster than DNA
Answer:
1. RNA evolves slowly

Question 45.
In the Hershey and Chase experiment, radioactive 35 S labelled
1. Cytosol of bacteria
2. Phage DNA
3. Protein coat of bacteriophage
4. Bacterial DNA
Answer:
3. Protein coat of bacteriophage

Question 46.
A cluster of closely associated structural and regulatory genes functioning together is called
1. Genetic code
2. Operon
3. Monocistronic gene
4. Regulon
Answer:
2. Operon

Question 47.
Heterogeneous nuclear RNA (hnRNA) is converted into mRNA through
1. Splicing only
2. Capping only
3. Tailing only
4. All of the above
Answer:
4. All of the above

Question 48.
The number of sense codons coding for amino acids is
1. 60
2. 64
3. 61
4. 32
Answer:
3. 61

Question 49.
Identify the correct statement.
1. ACG codes for Asparagine
2. UGU codes for Tyrosine
3. CGA codes for Serine
4. GUA codes for Valine
Answer:
4. GUA codes for Valine

Question 50.
Which of the following is NOT a feature of the genetic code?
1. It is degenerate
2. It is nearly universal
3. It is non-continuous
4. It is unambiguous
Answer:
3. It is non-continuous

Question 51.
The functional unit of a gene is known as
1. Muton
2. Cistron
3. Intron
4. Recon
Answer:
2. Cistron

Question 52.
Mature (processed) mRNA contains
1. Exons only
2. Introns only
3. Exons and introns
4. Capping at 3′ end
Answer:
1. Exons only

Question 53.
The RNA molecule that performs both structural and catalytic functions during translation is
1. tRNA
2. rRNA
3. sRNA
4. mRNA
Answer:
2. rRNA

Question 54.
Ochoa’s enzyme refers to
1. DNA polymerase
2. Polynucleotide phosphorylase
3. Peptidyl transferase
4. DNA ligase
Answer:
3. Peptidyl transferase

Question 55.
The gene responsible for producing the repressor protein is
1. Promoter gene
2. Structural gene
3. Regulator gene
4. Operator gene
Answer:
3. Regulator gene

Question 56.
The attachment site for the repressor protein produced by the regulator gene is the
1. Structural gene
2. Promoter region
3. Operator gene
4. Inducer
Answer:
3. Operator gene

Question 57.
The rule stating that in DNA the amount of adenine equals thymine and guanine equals cytosine is called
1. Jordan’s rule
2. Chargaff’s rule
3. Aflen’s rule
4. Stahl’s rule
Answer:
2. Chargaff’s rule

Question 58.
Purines are chemically classified as
1. Monocycic
2. Dicyclic and heterocyclic
3. Homocycic
4. Dicyclic and homocyclic
Answer:
2. Dicyclic and heterocyclic

Question 59.
A phosphate group is attached to the 5′-OH of a nucleotide through
1. Glycosidic linkage
2. Hydrogen linkage
3. Phosphoester linkage
4. Both (1) & (2)
Answer:
3. Phosphoester linkage

Question 60.
In the Lac operon, the inducer combines with
1. Promoter gene
2. Repressor protein
3. Repressor gene
4. Operator gene
Answer:
2. Repressor protein

Reviewing AP Inter 2nd Year Botany Study Material Chapter 2 Principles of Inheritance and Variation Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Botany 2nd Lesson Principles of Inheritance and Variation Questions and Answers

IV. Very Short Answer Questions

Question 1.
What is the cross between the F₁ progeny and a homozygous recessive parent called? How is it useful?
Answer:

1. Such a cross is known as a Test Cross.
2. It is used to identify the genotype of the organism being tested.

Question 2.
Do you think Mendel’s laws of inheritance would have been different if the characters he chosen were located on the same chromosome?
Answer:
Yes. If the genes for different characters were present on the same chromosome, they would tend to be inherited together and would not follow Mendel’s Law of Independent Assortment

Question 3.
Who proposed the chromosome theory of inheritance? [AP MAR-17,19]
Answer:
Sutton and Boveri.

Question 4.
Define true breeding and mention its significance.
Answer:

1. True Breeding: Continuous self-pollination over generations, resulting in offspring with the same traits, is called true breeding.
2. Significance: It ensures the stable inheritance and expression of traits through many generations.

Question 5.
Explain the terms phenotype and genotype. [AP MAR-16,23,24]
Answer:

• The observable physical appearance of an organism is called its Phenotype.
• The genetic constitution of an organism is called its Genotype.

Question 6.
What is linkage?
Answer:
Linkage is the tendency of genes located on the same chromosome to remain associated and get inherited together.

Question 7.
What will be the phenotypic ratio in the offspring obtained from the following crosses?
a) AA x aa
b) Aa x Aa
Note: Gene A is dominant over gene a.
Answer:
a) 1: 1
b) 3: 1.

Question 8.
In garden peas, the gene T for tall is dominant over its allele for dwarf. Give the genotypes of the parents in the following crosses.
a) Tall × Dwarf producing all tall plants.
b) Tall × dwarf producing half tall and half dwarf.
Answer:
(a) Tall x Dwarf → All tall plants: To obtain all tall offspring, the tall parent must be homozygous dominant (TT) and the dwarf parent must be homozygous recessive (tt). Genotypes: TT × tt
(b) Tall × Dwarf → Half tall and half dwarf (1:1 ratio): This ratio is obtained when the tall parent is heterozygous (Tt) and the dwarf parent is tt. Genotypes: Tt x tt