CBSE Class 12 Biology MCQs with Answers & Explanations (NCERT): Evolution

Course & Examination Details

• Course: CBSE Class 12 Biology
• Unit: Unit II – Genetics and Evolution
• Chapter: Chapter 7 – Evolution
• Prescribed Textbook: NCERT Biology Class XII
• Examination: CBSE Class 12 Board Examination
• Question Type: Multiple Choice Questions (MCQs)
• Coverage: Conceptual, application-based, competency-oriented (NCERT-aligned)

Section A: Origin of Life

Q1. The theory explaining origin of life from non-living matter is:

A. Special creation
B. Spontaneous generation
C. Chemical evolution
D. Vitalism

Correct Answer: C
Explanation: Chemical evolution proposes gradual formation of organic molecules from inorganic substances under primitive Earth conditions.

Q2. The primitive Earth atmosphere was mainly:

A. Oxidising
B. Neutral
C. Reducing
D. Rich in oxygen

Correct Answer: C
Explanation: Early Earth lacked free oxygen and had methane, ammonia, hydrogen, and water vapour.

Q3. The theory of chemical evolution was proposed by:

A. Darwin and Wallace
B. Miller and Urey
C. A. I. Oparin and J. B. S. Haldane
D. Lamarck and Mendel

Correct Answer: C
Explanation: Oparin and Haldane independently proposed chemical evolution of life.

Q4. The Miller–Urey experiment demonstrated:

A. Origin of first cell
B. Formation of proteins
C. Abiotic synthesis of organic molecules
D. Origin of oxygen atmosphere

Correct Answer: C
Explanation: The experiment showed amino acids could form under simulated primitive Earth conditions.

Q5. The earliest organisms were:

A. Aerobic and autotrophic
B. Anaerobic and heterotrophic
C. Aerobic and heterotrophic
D. Anaerobic and autotrophic

Correct Answer: B
Explanation: Oxygen was absent initially, so early organisms were anaerobic heterotrophs.

Section B: Evidences for Evolution

Q6. Homologous organs indicate:

A. Convergent evolution
B. Divergent evolution
C. Parallel evolution
D. Mutation

Correct Answer: B
Explanation: Homologous organs share common ancestry but perform different functions.

Q7. Wings of birds and insects are examples of:

A. Homologous organs
B. Vestigial organs
C. Analogous organs
D. Atavistic organs

Correct Answer: C
Explanation: They have similar functions but different origins, indicating convergent evolution.

Q8. Which structure is vestigial in humans?

A. Heart
B. Appendix
C. Brain
D. Kidney

Correct Answer: B
Explanation: Appendix has lost its original digestive function.

Q9. Fossils provide evidence of evolution by showing:

A. Sudden appearance of species
B. Fixity of species
C. Gradual change over time
D. Only living forms

Correct Answer: C
Explanation: Fossil records reveal transitional forms and gradual evolutionary changes.

Q10. Archaeopteryx is considered a connecting link between:

A. Amphibians and reptiles
B. Reptiles and birds
C. Birds and mammals
D. Fish and amphibians

Correct Answer: B
Explanation: It shows reptilian and avian features.

Section C: Adaptive Radiation

Q11. Adaptive radiation refers to:

A. Evolution of similar traits in different species
B. Rapid speciation from a common ancestor
C. Sudden mutation
D. Gene flow

Correct Answer: B
Explanation: It involves diversification into multiple species adapted to different niches.

Q12. Darwin’s finches illustrate:

A. Convergent evolution
B. Artificial selection
C. Adaptive radiation
D. Genetic drift

Correct Answer: C
Explanation: Finches evolved varied beak shapes from a common ancestor.

Q13. Adaptive radiation is an example of:

A. Parallel evolution
B. Convergent evolution
C. Divergent evolution
D. Neutral evolution

Correct Answer: C
Explanation: Species diverge from a common ancestor.

Q14. Australian marsupials diversified due to:

A. Artificial selection
B. Genetic drift only
C. Adaptive radiation
D. Mutation pressure

Correct Answer: C
Explanation: Isolation and niche availability led to diversification.

Q15. Occupation of different ecological niches reduces:

A. Variation
B. Competition
C. Speciation
D. Mutation

Correct Answer: B
Explanation: Niche differentiation reduces interspecific competition.

Section D: Biological Evolution (Theories)

Q16. The inheritance of acquired characters was proposed by:

A. Jean-Baptiste Lamarck
B. Charles Darwin
C. Wallace
D. Mendel

Correct Answer: A
Explanation: Lamarck proposed use and disuse with inheritance of acquired traits.

Q17. Lamarckism was rejected because:

A. Variations do not exist
B. Acquired traits are not inherited
C. Natural selection does not occur
D. Fossils do not exist

Correct Answer: B
Explanation: Only germline changes are inherited, not somatic changes.

Q18. Natural selection primarily acts on:

A. Genes
B. Individuals
C. Populations
D. Species

Correct Answer: B
Explanation: Individuals with favourable traits survive and reproduce more.

Q19. “Survival of the fittest” refers to:

A. Strongest organisms only
B. Most intelligent organisms
C. Best adapted organisms
D. Largest organisms

Correct Answer: C
Explanation: Fitness refers to reproductive success in a given environment.

Q20. Darwinism explains evolution mainly through:

A. Use and disuse
B. Mutation alone
C. Natural selection
D. Genetic drift

Correct Answer: C
Explanation: Natural selection is the central mechanism.

Section E: Mechanism of Evolution

Q21. Mutation introduces:

A. Stability
B. Genetic variation
C. Gene flow
D. Selection pressure

Correct Answer: B
Explanation: Mutations create new alleles.

Q22. Gene flow occurs due to:

A. Mutation
B. Selection
C. Migration
D. Recombination

Correct Answer: C
Explanation: Movement of individuals transfers alleles between populations.

Q23. Genetic drift is significant in:

A. Large populations
B. Small populations
C. Stable populations
D. Random mating populations

Correct Answer: B
Explanation: Random effects are stronger in small populations.

Q24. Founder effect is a type of:

A. Mutation
B. Natural selection
C. Genetic drift
D. Recombination

Correct Answer: C
Explanation: Small founding populations carry limited alleles.

Q25. Which process increases variation without changing allele frequency directly?

A. Mutation
B. Recombination
C. Selection
D. Drift

Correct Answer: B
Explanation: Recombination reshuffles existing alleles.

Section F: Hardy–Weinberg Principle

Q26. Hardy–Weinberg equilibrium applies to:

A. Individuals
B. Populations
C. Species
D. Communities

Correct Answer: B
Explanation: It describes allele frequencies at the population level.

Q27. The Hardy–Weinberg equation is:

A. p + q = 2
B. p² + q² = 1
C. p² + 2pq + q² = 1
D. p³ + q³ = 1

Correct Answer: C
Explanation: It represents genotype frequencies.

Q28. Random mating is required to:

A. Increase mutation
B. Maintain equilibrium
C. Cause evolution
D. Reduce variation

Correct Answer: B
Explanation: Non-random mating disturbs allele frequencies.

Q29. Deviation from Hardy–Weinberg equilibrium indicates:

A. Genetic stability
B. No evolution
C. Evolution occurring
D. Population extinction

Correct Answer: C
Explanation: Evolutionary forces alter allele frequencies.

Q30. Which is NOT a condition of Hardy–Weinberg equilibrium?

A. Large population
B. No mutation
C. Natural selection
D. Random mating

Correct Answer: C
Explanation: Natural selection disturbs equilibrium.

Section G: Human Evolution

Q31. The ape-like ancestor of humans was:

A. Homo habilis
B. Homo erectus
C. Dryopithecus
D. Homo sapiens

Correct Answer: C
Explanation: Dryopithecus showed arboreal ape-like traits.

Q32. The earliest tool-using human was:

A. Homo erectus
B. Homo habilis
C. Homo neanderthalensis
D. Homo sapiens

Correct Answer: B
Explanation: Homo habilis used simple stone tools.

Q33. The first human to use fire was:

A. Homo habilis
B. Homo sapiens
C. Homo erectus
D. Dryopithecus

Correct Answer: C
Explanation: Homo erectus used fire and lived upright.

Q34. Modern humans belong to:

A. Homo erectus
B. Homo neanderthalensis
C. Homo sapiens
D. Australopithecus

Correct Answer: C
Explanation: Homo sapiens are modern humans.

Q35. Human evolution is believed to have originated in:

A. Asia
B. Europe
C. Africa
D. Australia

Correct Answer: C
Explanation: Fossil and molecular evidence support African origin.

Section H: Patterns of Natural Selection

Q36. Stabilising selection favours:

A. Extreme phenotypes
B. Intermediate phenotypes
C. New mutations
D. Random traits

Correct Answer: B
Explanation: It maintains population stability.

Q37. Directional selection results in:

A. No change
B. Elimination of extremes
C. Shift towards one extreme
D. Speciation only

Correct Answer: C
Explanation: One extreme trait becomes more common.

Q38. Disruptive selection leads to:

A. Uniform population
B. Reduced variation
C. Increased extremes
D. No evolution

Correct Answer: C
Explanation: Both extremes are favoured over intermediates.

Q39. Antibiotic resistance in bacteria is an example of:

A. Stabilising selection
B. Disruptive selection
C. Directional selection
D. Genetic drift

Correct Answer: C
Explanation: Selection favours resistant strains.

Q40. Natural selection acts directly on:

A. Genotype
B. Phenotype
C. Allele frequency
D. DNA sequence

Correct Answer: B
Explanation: Selection operates on expressed traits.

Section I: Integrated & Board-Oriented MCQs

Q41. Evolution is best described as a change in:

A. Individuals
B. Populations
C. Ecosystems
D. Communities

Correct Answer: B
Explanation: Evolution involves changes in population allele frequencies.

Q42. Which factor does NOT cause evolution?

A. Mutation
B. Gene flow
C. Random mating
D. Natural selection

Correct Answer: C
Explanation: Random mating maintains equilibrium.

Q43. Molecular similarities between species indicate:

A. Environmental influence
B. Common ancestry
C. Artificial selection
D. Genetic drift

Correct Answer: B
Explanation: Similar DNA/proteins suggest shared ancestry.

Q44. Which evidence is most direct for evolution?

A. Molecular
B. Embryological
C. Fossil
D. Anatomical

Correct Answer: C
Explanation: Fossils provide direct historical records.

Q45. Evolutionary changes occur due to interaction of:

A. Environment only
B. Genetics only
C. Genetics and environment
D. Behaviour only

Correct Answer: C
Explanation: Variation (genetics) and selection (environment) interact.

Section J: Higher-Order Thinking MCQs

Q46. A small isolated population suddenly increases in size. Which effect is seen?

A. Bottleneck effect
B. Founder effect
C. Stabilising selection
D. Gene flow

Correct Answer: B
Explanation: New population reflects genes of founders.

Q47. Which concept best explains biodiversity?

A. Mutation alone
B. Adaptive radiation
C. Genetic drift only
D. Use and disuse

Correct Answer: B
Explanation: Adaptive radiation generates multiple species.

Q48. Evolutionary fitness refers to:

A. Physical strength
B. Longevity
C. Reproductive success
D. Intelligence

Correct Answer: C
Explanation: Fitness is measured by contribution to next generation.

Q49. Which statement about evolution is correct?

A. Individuals evolve
B. Evolution is sudden
C. Evolution is continuous
D. Evolution has stopped

Correct Answer: C
Explanation: Evolution is an ongoing population process.

Q50. Evolutionary theory integrates which disciplines?

A. Genetics only
B. Ecology only
C. Palaeontology only
D. Genetics, ecology, palaeontology

Correct Answer: D
Explanation: Evolution draws evidence from multiple biological fields.

✔ Strictly NCERT-Based | ✔ CBSE Board Pattern | ✔ Concept-Clearing MCQs

🎯 Targeting Exams Section

This MCQ set is carefully designed to help students prepare for:

• CBSE Class 12 Biology Board Examination

• CBSE Pre-Board and Unit Tests

• CBSE Compartment & Improvement Exams

• NEET (UG) – Concept Reinforcement Level

• State Board Class 12 Exams aligned with NCERT syllabus

The questions follow the latest CBSE competency-based MCQ pattern, emphasizing conceptual understanding, application, and analytical thinking.

🔑 Related Keyphrases 

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