Part 1: Origin of Life (Q1–Q25)
Chapter 6 “Evolution” is one of the most conceptual and high-weightage chapters for CBSE Class 12 Biology and NEET UG.
200 MCQs in 8 Parts (25 each) with detailed explanations, strictly as per NCERT.
Subtopic Breakdown – Chapter 6: Evolution
- Origin of Life (Oparin-Haldane theory, Miller-Urey experiment, early earth conditions)
- Evidence for Evolution (Palaeontology, comparative anatomy, embryology, molecular evidence)
- Darwin’s Contribution (Natural selection, observations from Galapagos finches, Lamarck vs Darwin)
- Modern Synthetic Theory of Evolution (Mutation, recombination, variation, genetic basis)
- Mechanism of Evolution: Natural Selection (Types of natural selection with examples)
- Hardy-Weinberg Principle (Gene pool, allele frequency, genetic equilibrium)
- Gene Flow and Genetic Drift (Founder effect, bottleneck effect, migration)
- Adaptive Radiation & Human Evolution (Darwin’s finches, Australian marsupials, human ancestors)
Part 1: Origin of Life (Q1–Q25)
Q1. Which gases were present in the primitive atmosphere of Earth?
a) Oxygen, nitrogen, methane, ammonia
b) Hydrogen, methane, ammonia, water vapor
c) Carbon dioxide, oxygen, nitrogen
d) Ozone, nitrogen, oxygen
Answer: b
- b) Correct: Primitive Earth atmosphere was reducing, rich in H₂, CH₄, NH₃, H₂O vapor.
- a, c, d) Contain oxygen/ozone → not present initially.
Q2. The “Big Bang Theory” explains:
a) Origin of Earth’s atmosphere
b) Origin of Universe
c) Origin of Life
d) Geological time scale
Answer: b
- b) Correct: Big Bang theory explains origin of universe (~20 billion years ago).
Q3. Life originated about:
a) 20 billion years ago
b) 4.5 billion years ago
c) 3.5 billion years ago
d) 2.5 billion years ago
Answer: c
- c) Correct: Earliest life forms appeared ~3.5 bya.
Q4. Oparin and Haldane proposed that life originated:
a) Spontaneously from non-living matter in the past
b) From outer space
c) From pre-existing life
d) Through divine creation
Answer: a
- a) Correct: Oparin-Haldane → chemical evolution hypothesis.
Q5. The theory that life came from space is called:
a) Abiogenesis
b) Biogenesis
c) Cosmozoic or Panspermia theory
d) Special creation
Answer: c
- c) Correct: Panspermia → life originated elsewhere, came to Earth via meteorites.
Q6. Miller–Urey experiment demonstrated:
a) Formation of DNA in primitive earth
b) Synthesis of simple organic molecules
c) Evolution of photosynthesis
d) Formation of ozone layer
Answer: b
- b) Correct: Miller–Urey created amino acids and simple organics under primitive conditions.
Q7. Which scientist disproved spontaneous generation of life by showing maggots come from flies?
a) Pasteur
b) Spallanzani
c) Redi
d) Darwin
Answer: c
- c) Correct: Francesco Redi (1668) disproved abiogenesis with his meat-maggot experiment.
Q8. Which scientist finally disproved spontaneous generation of microorganisms?
a) Pasteur
b) Lamarck
c) Oparin
d) Darwin
Answer: a
- a) Correct: Louis Pasteur showed life comes only from pre-existing life.
Q9. The first organisms on Earth were:
a) Autotrophs
b) Heterotrophs
c) Photosynthetic bacteria
d) Fungi
Answer: b
- b) Correct: First life forms were heterotrophs, using available organic molecules.
Q10. Coacervates are:
a) Living cells
b) Protein–nucleic acid complexes formed during chemical evolution
c) Viruses
d) Enzymes
Answer: b
- b) Correct: Coacervates = non-living aggregates of biomolecules → precursors of cells.
Q11. Ozone layer was formed when:
a) Earth cooled
b) Cyanobacteria released oxygen
c) Volcanoes erupted
d) DNA evolved
Answer: b
- b) Correct: Cyanobacteria → photosynthesis → O₂ → O₃ layer.
Q12. Which energy sources were available on primitive Earth?
a) UV rays, lightning, volcanic heat
b) Nuclear power
c) Solar panels
d) Fossil fuels
Answer: a
- a) Correct: Primitive Earth → UV, lightning, heat were main energy sources.
Q13. Who coined the term “primordial soup” for early oceans rich in organic molecules?
a) Oparin
b) Haldane
c) Darwin
d) Miller
Answer: b
- b) Correct: Haldane → oceans became “hot dilute soup” of organics.
Q14. Prokaryotes evolved approximately:
a) 3.5 billion years ago
b) 2 billion years ago
c) 4.5 billion years ago
d) 500 million years ago
Answer: a
- a) Correct: Earliest fossils (stromatolites) ~3.5 bya.
Q15. Eukaryotes evolved around:
a) 4.5 bya
b) 2 bya
c) 1 bya
d) 500 mya
Answer: b
- b) Correct: Eukaryotes evolved ~2 bya.
Q16. Which hypothesis suggests mitochondria and chloroplasts were once free-living bacteria?
a) Panspermia
b) Endosymbiotic theory
c) Abiogenesis
d) Gene flow
Answer: b
- b) Correct: Endosymbiotic theory (Margulis).
Q17. The reducing atmosphere was essential for:
a) Formation of ozone
b) Synthesis of organic molecules
c) Aerobic respiration
d) Photosynthesis
Answer: b
- b) Correct: No oxygen = reducing → favored abiotic synthesis of organics.
Q18. Which gas was absent in primitive Earth atmosphere?
a) O₂
b) CH₄
c) NH₃
d) H₂
Answer: a
- a) Correct: Oxygen was absent initially.
Q19. Protobionts were:
a) Non-living aggregates with membrane-like structure
b) Fully living cells
c) Viruses
d) DNA strands
Answer: a
- a) Correct: Protobionts (coacervates, microspheres) = non-living pre-cell structures.
Q20. Miller–Urey experiment produced:
a) Proteins
b) Amino acids
c) DNA
d) RNA
Answer: b
- b) Correct: Amino acids like glycine, alanine.
Q21. Earliest photosynthetic organisms were:
a) Green algae
b) Cyanobacteria
c) Fungi
d) Ferns
Answer: b
- b) Correct: Cyanobacteria → O₂ releasing photosynthesis.
Q22. Which evidence supports chemical evolution of life?
a) Laboratory synthesis of amino acids
b) Discovery of fossils
c) Evolution of birds
d) Hardy–Weinberg principle
Answer: a
- a) Correct: Miller’s experiment supports abiotic origin of biomolecules.
Q23. In origin of life, first genetic material was likely:
a) DNA
b) RNA
c) Protein
d) Lipid
Answer: b
- b) Correct: RNA world hypothesis → RNA acted as genetic + catalytic molecule.
Q24. Which property of RNA supports RNA world hypothesis?
a) Catalytic ability (ribozymes)
b) Stability
c) Double-stranded nature
d) High mutation resistance
Answer: a
- a) Correct: RNA can act as enzyme (ribozyme).
Q25. Fossil stromatolites provide evidence for:
a) Earliest fungi
b) Earliest cyanobacteria
c) Earliest plants
d) Earliest animals
Answer: b
- b) Correct: Stromatolites = fossilized cyanobacteria colonies (~3.5 bya).
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