Evolution Questions and Answers AP Inter 2nd Year Zoology Chapter 5

Reviewing AP Inter 2nd Year Zoology Study Material Chapter 5 Evolution Questions and Answers can help students prepare confidently for exams.

AP Inter 2nd Year Zoology 5th Lesson Evolution Questions and Answers

IV. Very Short Answer Questions

Question 1.
What is Convergent evolution?
Answer:
Convergent evolution is the evolutionary process in which unrelated organisms independently develop similar structures or adaptations because they live under similar environmental conditions, even though they do not share a recent common ancestor. Example: Wings of birds and insects.

Question 2.
What are Mutations?
Answer:
Mutations are alterations in the DNA sequence that result in changes in an organism’s genotype and may also affect its phenotype.

Question 3.
What is the significance of Coelacanth fish?
Answer:
The significance of Coelacanth lies in the following:

1. It is regarded as a “living fossil” because it was believed to be extinct but was discovered alive in 1938.
2. It provides valuable evidence for evolution, particularly the transition from fishes to amphibians due to its lobe-finned structure.

Question 4.
What is founder effect?
Answer:

1. Founder effect is a form of genetic drift in which a new population is established by a small group of individuals.
2. As a result, the new population shows reduced genetic diversity and different allele frequencies compared to the original population.

Question 5.
What are the two key concepts of Darwin’s theory of Evolution?
Answer:
The two fundamental ideas of Darwin’s theory are:

1. Branching Descent: All organisms originate from common ancestors and gradually diversify over time, producing new species and evolutionary branches.
2. Natural Selection: Organisms possessing advantageous variations are better adapted to their environment. They survive and reproduce successfully, passing these favourable traits to future generations.

V. Short Answer Questions

Question 1.
Explain the Hardy-Weinberg principle.
Answer:
The Hardy-Weinberg principle states that allele frequencies within a population remain constant from one generation to the next when no evolutionary forces act upon it. This stable condition is known as genetic equilibrium.

1. Mathematical Expression: For a gene with two alleles, A and a:

• If p represents the frequency of allele A and q represents the frequency of allele a, then p + q = 1
• Frequency of homozygous dominant individuals (AA) = p²
• Frequency of homozygous recessive individuals (aa) = q²
• Frequency of heterozygous individuals (Aa) = 2pq
• Therefore, p² + 2pq + q² = 1

2. Evolutionary Significance: Any deviation from the expected Hardy-Weinberg frequencies indicates that evolutionary changes are occurring within the population.

3. Factors Disturbing Genetic Equilibrium :

• Gene migration (Gene flow): Movement of alleles into or out of a population.
• Genetic drift: Random fluctuations in allele frequencies.
• Mutation: Sudden changes in genetic material.
• Genetic recombination: Formation of new gene combinations during gamete production
• Natural selection: Differential survival and reproduction of individuals with favourable traits.

Question 2.
Give an account of the evolution of Man.
Answer:

1. Human evolution is a gradual process that traces the development of modern humans from primitive primate ancestors over millions of years.
2. Early primates such as Dryopithecus and Ramapithecus (about 15 million years ago) were hairy, ape-like forms. Dryopithecus was more ape-like, whereas Ramapithecus showed more human-like characteristics.
3. Later, Australopithecus (around 3-4 million years ago) appeared in East Africa. They walked upright, used simple tools, and mainly fed on fruits.
4. Homo habilis was the first human-like species. It possessed a brain capacity of approximately 650 – 800 cc and is called the “handyman” because of its tool-making ability.
5. Homo erectus (about 1.5 million years ago) had a larger brain of nearly 900 cc, walked completely upright, used fire, and probably consumed meat.
6. Neanderthal man (100,000 – 10,000 years ago) had a brain size of about 1400 cc. They used animal skins for clothing and practiced burial of the dead, indicating social organization.
7. Finally, Homo sapiens evolved in Africa during the last Ice Age (about 75,000 – 10,000 years ago) and later spread across the globe, developing advanced language, culture, and intelligence.

Question 3.
Explain Miller’s experiment of chemical evolution.
Answer:

1. Miller designed a closed experimental setup containing methane (CH₄), ammonia (NH₃), hydrogen (H₂), and water (H₂O) to simulate primitive Earth conditions.
2. Water was heated to generate water vapour, while electric sparks were passed through the gaseous mixture to imitate lightning.
3. The steam mixed continuously with methane, ammonia, and hydrogen gases inside the apparatus.
4. The electrical discharges supplied energy, and the vapours were cooled and condensed repeatedly, creating a continuous cycle.
5. After several days, a dark brown coloured solution accumulated in the system.
6. Analysis revealed the presence of organic molecules, including amino acids such as glycine and alanine, which are basic building blocks of proteins.
7. The experiment demonstrated that essential organic compounds can be synthesized from non-living substances under primitive Earth conditions, supporting the theory of chemical evolution.

Question 4.
Explain adaptive radiation with suitable examples.
Answer:

1. Adaptive radiation is an evolutionary phenomenon in which multiple species evolve from a common ancestor within a specific geographical region and adapt to different ecological niches.
2. These species arise from a shared ancestral stock and gradually diversify to exploit different habitats and resources.
3. A classic example is Darwin’s finches, where various finch species evolved from a common seed-eating ancestor and developed distinct beak types suited to different food habits.
4. Another example is the Australian marsupials, which evolved from a common ancestral form and adapted to a wide range of habitats in Australia.
5. Under similar environmental pressures, some organisms may evolve comparable adaptations, as seen in placental mammals and marsupials such as the placental wolf and Tasmanian wolf.

Question 5.
Explain the homologous and analogous organs with suitable examples.
Answer:
I) Homologous Organs: Homologous organs are structures that share a common origin and basic structural plan but perform different functions. They are evidence of divergent evolution, where related organisms evolve in different directions to meet different environmental demands.

Examples:

• Forelimbs of whale, bat, cheetah, and human-same structural pattern but different functions such as swimming, flying, running, and grasping.
• Hearts or brains of vertebrates,
• Thorns of Bougainvillea and tendrils of Cucurbita.

II) Analogous Organs: Analogous organs are structures that differ in origin and anatomy but perform similar functions.
They arise through convergent evolution, where unrelated organisms independently develop similar adaptations.

Examples:

• Wings of birds and butterflies → same function (flight) but different structure.
• Eyes of octopuses and mammals → same function (vision) but different evolutionary origin.
• Flippers of penguins and dolphins.
• Sweet potato (root) and potato (stem) → both functioning as food storage organs.

I. Multiple Choice Questions

Question 1.
The following is incorrect regarding the conditions of the atmosphere on early Earth.
1. High Temperature
2. Reduced atmosphere
3. Volcanic storms
4. Free Oxygen
Answer:
4. Free Oxygen

Question 2.
Darwin’s finches is an example for the concept of
1. Convergent evolution
2. Adaptive radiation
3. Connecting link
4. Homology
Answer:
2. Adaptive radiation

Question 3.
Match the following.

A B C D
1) 4 3 2 1
2) 1 2 3 4
3) 2 1 4 3
4) 3 4 2 1
Answer:
1) 4 3 2 1

Question 4.
The biggest dinosaur that lived on Earth is
1. Ichthyosaurus
2. Tyrannosaurus rex
3. Brachiosaurus
4. Triceratops
Answer:
2. Tyrannosaurus rex

Question 5.
The idea of mutation was first introduced by
1. Gregor Johan Mendel
2. Hugo de Vries
3. Lamarck
4. Malthus
Answer:
2. Hugo de Vries

Question 6.
Which of the following are indicators of the industrial pollution?
1. Lichens
2. Bacteria
3. Viruses
4. Insects
Answer:
1. Lichens

Question 7.
Match the following.

A B C D
1) 2 3 1 4
2) 4 2 1 3
3) 3 2 1 4
4) 2 1 4 3
Answer:
1) 2 3 1 4

Question 8.
Which of the following will not affect the Hardy-Weinberg equilibrium
1. Genetic drift
2. Genetic recombination
3. Natural selection
4. Constant gene pool
Answer:
4. Constant gene pool

Question 9.
Identify the type of natural selection which favours medium/intermediate phenotypes
1. Directional
2. Stabilising
3. Disruptive
4. Artificial
Answer:
2. Stabilising

Question 10.
Assertion: During the Industrial Revolution in England, the population of white-winged moths increased while the dark-winged moths decreased.
Reason: Dark-winged moths were better camouflaged against the soot-darkened tree trunks, making them less likely to be eaten by the predators.
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 is false and Reason is true.
Answer:
4. If Assertion is false and Reason is true.

Question 11.
Identify the correct sequence of evolution of man.
1. Ramapithecus – Dryopithecus – Homo habilis – Neanderthal
2. Dryopithecus – Homo habilis – Homo erectus – Homo sapiens
3. Australopithecus – Ramapithecus – Neanderthal – Dryopithecus
4. Homo erectus – Homo habilis – Dryopithecus – Homo sapiens
Answer:
2. Dryopithecus – Homo habilis – Homo erectus – Homo sapiens

II. Fill in the Blanks

1. Darwin’s finches were found in the ………………………… island.
Answer:
Galapagos

2. The wings of the butterfly and bird are example for …………………… organs.
Answer:
Analogous

3. Placental wolf and Tasmanian wolf are examples of ……………………….. .
Answer:
Convergent evolution

4. Sudden change in allele frequency by chance is called ……………………………. .
Answer:
Genetic drift

5. The theory which says the life came from outer space is ………………………………. .
Answer:
Panspermia

III. One Word Answer Questions

Question 1.
Who proposed that life formed from pre-existing non-living molecules?
Answer:
Oparin and Haldane.

Question 2.
Who conducted the sterilized flask experiments to disprove the theory of spontaneous generation?
Answer:
Louis Pasteur.

Question 3.
What do homologous organs indicate?
Answer:
Common ancestry/ Divergent evolution.

Question 4.
What is the size of the brain of Homo erectus?
Answer:
Around 900 cc.

Question 5.
When did the first cellular form of life appear on Earth?
Answer:
2000 million years ago.

Objective Questions

Question 1.
Evolution is described as the gradual change in the characteristics of organisms over:
1. Space
2. Cells
3. Individuals
4. Generations
Answer:
4. Generations

Question 2.
Who proposed the theory of natural selection?
1. Lamarck
2. Darwin
3. Mendel
4. Watson
Answer:
2. Darwin

Question 3.
Organs that perform the same function but have different origins are known as:
1. Analogous
2. Homologous
3. Vestigial
4. Mutated
Answer:
1. Analogous

Question 4.
The human appendix is considered an example of:
1. Active organ
2. Vestigial organ
3. Mutation
4. Drift
Answer:
2. Vestigial organ

Question 5.
Evolution takes place at the level of:
1. Individual
2. Population
3. Cell
4. Tissue
Answer:
2. Population

Question 6.
The branch of science that deals with the study of fossils is called:
1. Paleontology
2. Morphology
3. Cytology
4. Ecology
Answer:
1. Paleontology

Question 7.
Natural selection primarily acts on:
1. Genotype
2. Phenotype
3. DNA
4. Chromosomes
Answer:
2. Phenotype

Question 8.
Adaptive radiation refers to the evolution of:
1. Same species
2. Different species from common ancestor
3. Mutations
4. Isolated species
Answer:
2. Different species from common ancestor

Question 9.
The primary source of new genes in a population is:
1. Mutation
2. Drift
3. Selection
4. Isolation
Answer:
1. Mutation

Question 10.
Homologous organs provide evidence for:
1. Convergent evolution
2. Divergent evolution
3. Mutation
4. Drift
Answer:
2. Divergent evolution

Question 11.
The wings of birds and insects are examples of:
1. Homologous organs
2. Analogous organs
3. Vestigial organs
4. Mutations
Answer:
2. Analogous organs

Question 12.
Darwin carried out his famous study on finches in:
1. India
2. Galapagos Islands
3. Africa
4. Europe
Answer:
2. Galapagos Islands

Question 13.
Fossils are most commonly found in:
1. Igneous rocks
2. Metamorphic rocks
3. Sedimentary rocks
4. Lava
Answer:
3. Sedimentary rocks

Question 14.
The process involving changes in allele frequency is known as:
1. Growth
2. Isolation
3. Mutation
4. Evolution
Answer:
4. Evolution

Question 15.
The study of embryonic similarities among organisms supports:
1. Common ancestry
2. Isolation
3. Mutation
4. Drift
Answer:
1. Common ancestry

Question 16.
Which example demonstrates divergent evolution from a common ancestor?
1. Butterfly wing and bird wing
2. Bird wing and insect wing
3. Human arm and whale flipper
4. Fish fins only
Answer:
3. Human arm and whale flipper

Question 17.
Gradual change in a population through natural selection is known as:
1. Drift
2. Evolution
3. Mutation
4. Isolation
Answer:
2. Evolution

Question 18.
Which provides molecular evidence for evolution?
1. Habitat
2. DNA similarities
3. Fossils
4. Organs
Answer:
2. DNA similarities

Question 19.
A common structural plan in different organisms indicates:
1. Mutation
2. Homology
3. Analogy
4. Isolation
Answer:
2. Homology

Question 20.
Who proposed the inheritance of acquired characters?
1. Wallace
2. Lamarck
3. Darwin
4. Mendel
Answer:
2. Lamarck

Question 21.
According to Lamarck, traits acquired during life are:
1. Mutated
2. Ignored
3. Inherited
4. Lost
Answer:
3. Inherited

Question 22.
The survival of organisms mainly depends on their ability to:
1. Adapt to the environment
2. Grow larger
3. Stop reproduction
4. Avoid mutation
Answer:
1. Adapt to the environment

Question 23.
Which of the following is NOT considered evidence for evolution?
1. Morphology
2. DNA similarity
3. Photosynthesis
4. Fossils
Answer:
3. Photosynthesis

Question 24.
Differences in finch beaks are mainly associated with:
1. Food habits
2. Mutation only
3. Colour
4. Size Only
Answer:
1. Food habits

Question 25.
Evolution is a continuous process occurring over:
1. Seconds
2. Hours
3. Generations
4. Days
Answer:
3. Generations

Question 26.
Which option best represents convergent evolution?
1. Same structure
2. Same DNA
3. Same origin
4. Same Function, different origin
Answer:
4. Same Function, different origin

Question 27.
Vestigial organs are evidence of:
1. Evolutionary history
2. Mutation
3. Isolation
4. Drift
Answer:
1. Evolutionary history

Question 28.
An organ that has lost its original function but persists due to ancestry is called:
1. Functional organ
2. Mutated organ
3. Vestigial organ
4. Analogous organ
Answer:
3. Vestigial organ

Question 29.
Evidence comparing structural features of organisms is known as:
1. Genetic
2. Morphological
3. Fossil
4. Molecular
Answer:
2. Morphological

Question 30.
Darwin’s theory rejected the idea that species are:
1. Changing
2. Constant
3. Variable
4. Adaptive
Answer:
2. Constant

Question 31.
The major force responsible for natural selection is:
1. Environmental pressure
2. Drift
3. Mutation
4. Isolation
Answer:
1. Environmental pressure

Question 32.
Under Hardy-Weinberg equilibrium, allele frequencies remain unchanged when there is n0:
1. Population
2. Reproduction
3. Evolutionary force
4. Mutation
Answer:
3. Evolutionary force

Question 33.
The expression p² + 2pq + q² = 1 represents the distribution of: ‘
1. Mutations
2. Genotypes
3. Phenotypes
4. Genes
Answer:
2. Genotypes

Question 34.
Genetic drift is the change in allele frequency due to:
1. Selection
2. Migration
3. Chance events
4. Mutation
Answer:
3. Chance events

Question 35.
Genetic drift is more significant in populations that are:
1. Growing
2. Stable
3. Large
4. Small
Answer:
4. Small

Question 36.
Gene flow in a population occurs because of:
1. Drift
2. Selection
3. Migration
4. Mutation
Answer:
3. Migration

Question 37.
Which factor helps maintain genetic variation within a population?
1. Selection
2. Isolation
3. Mutation
4. Drift
Answer:
3. Mutation

Question 38.
Reproductive isolation is essential for:
1. Drift
2. Speciation
3. Mutation
4. Migration
Answer:
2. Speciation

Question 39.
Speciation due to geographical separation is termed:
1. Drift
2. Artificial
3. Sympatric
4. Allopatric
Answer:
4. Allopatric

Question 40.
Speciation that occurs within the same geographical area is called:
1. Adaptive
2. Artificial
3. Sympatric
4. Allopatric
Answer:
3. Sympatric

Question 41.
Behavioral differences preventing mating result in:
1. Drift
2. Selection
3. Isolation
4. Mutation
Answer:
3. Isolation

Question 42.
The frequency of the recessive allele (q) can be calculated from:
1. p²
2.2pq
3. q²
4. p
Answer:
3. q²

Question 43.
If q² = 0.25, then q equals:
1. 1
2. 0.25
3. 0.5
4. 0.75
Answer:
3. 0.5

Question 44.
Which factor tends to reduce genetic variation?
1. Mutation
2. Recombination
3. Migration
4. Genetic drift
Answer:
4. Genetic drift

Question 45.
Which of the following is a post-zygotic reproductive barrier?
1. Temporal isolation
2. Behavioral isolation
3. Mechanical isolation
4. Hybrid sterility
Answer:
4. Hybrid sterility

Question 46.
Hybrid sterility prevents:
1. Fertilization
2. Viable offspring reproduction
3. Mutation
4. Migration
Answer:
2. Viable offspring reproduction

Question 47.
The bottleneck effect is an example of:
1. Isolation
2. Mutation
3. Genetic drift
4. Selection
Answer:
3. Genetic drift

Question 48.
Loss of variation due to a sharp decline in population size is known as:, .
1. Selection
2. Mutation
3. Gene flow
4. Bottleneck effect
Answer:
4. Bottleneck effect

Question 49.
Evolutionary changes are generally slow because they occur over:
1. Seconds
2. Hours
3. Days
4. Generations
Answer:
4. Generations

Question 50.
Formation of a new species is called:
1. Isolation
2. Mutation
3. Drift
4. Speciation
Answer:
4. Speciation

Question 51.
Which factor does NOT disturb Hardy-Weinberg equilibrium?
1. Migration
2. Mutation
3. Random mating
4. Selection
Answer:
3. Random mating

Question 52.
Large populations are least affected by:
1. Migration
2. Mutation
3. Selection
4. Genetic drift
Answer:
4. Genetic drift

Question 53.
A change in the gene pool over time leads to:
1. Isolation
2. Evolution
3. Stability
4. Mutation only
Answer:
2. Evolution

Question 54.
Random changes in allele frequencies are mainly caused by:
1. Migration
2. Mutation
3. Selection
4. Genetic drift
Answer:
4. Genetic drift

Question 55.
Migration of individuals into a population results in:
1. Gene flow
2. Drift
3. Isolation
4. Mutation
Answer:
1. Gene flow

Question 56.
Evolution ultimately leads to:
1. Stability
2. Diversity
3. Uniformity
4. Isolation
Answer:
2. Diversity

Question 57.
Which force decreases genetic diversity?
1. Migration
2. Mutation
3. Recombination
4. Genetic drift
Answer:
4. Genetic drift

Question 58.
If p = 0.6 and q = 0.4, the heterozygous frequency (2pq) is:
1. 0.16
2. 0.48
3. 0.24
4. 0.36
Answer:
2. 0.48

Question 59.
A sudden reduction in population size causing random allele loss is called:
1. Mutation
2. Gene flow
3. Founder effect
4. Bottleneck effect
Answer:
4. Bottleneck effect

Question 60.
Which condition most strongly disturbs Hardy-Weinberg equilibrium?
1. No mutation
2. Large population size
3. Natural selection
4. Random mating
Answer:
3. Natural selection

Question 61.
The introduction of new alleles from another population is known as:
1. Drift
2. Selection
3. Mutation
4. Gene flow
Answer:
4. Gene flow

Question 62.
Evolution can occur without necessarily producing adaptation through:
1. Gene flow
2. Natural selection
3. Mutation
4. Genetic drift
Answer:
4. Genetic drift

Question 63.
If only individuals with extreme traits survive while intermediates are eliminated, it is called:
1. Artificial selection
2. Directional selection
3. Stabilizing selection
4. Disruptive selection
Answer:
4. Disruptive selection

Question 64.
A post-zygotic reproductive barrier reducing fitness of offspring is:
1. Mechanical isolation
2. Temporal isolation
3. Behavioral isolation
4. Hybrid breakdown
Answer:
4. Hybrid breakdown

Question 65.
When a small group colonizes a new area and establishes a population, the resulting genetic change is mainly due to:
1. Isolation
2. Founder effect
3. Mutation
4. Natural selection
Answer:
2. Founder effect

Question 66.
Hardy-Weinberg equilibrium assumes mating in a population is:
1. Seasonal
2. Restricted
3. Selective
4. Random
Answer:
4. Random