Chapter Exam

Chapter 6: Evolution — Online MCQ Test

Q: Who proposed that life originated from pre-existing non-living organic molecules through chemical evolution?

Answer: A. Oparin and Haldane — Oparin and Haldane suggested that the first life forms arose from pre-existing organic molecules under primitive Earth conditions.

Q: The primitive atmosphere of Earth was mainly:

Answer: B. Reducing and without free oxygen — According to NCERT, early Earth had a reducing atmosphere containing gases like methane, ammonia, hydrogen and water vapour, with no free oxygen.

Q: Two unrelated species living in similar habitats develop similar body forms. This is most likely due to:

Answer: B. Convergent evolution — Convergent evolution occurs when unrelated organisms independently evolve similar traits due to similar environmental pressures.

Q: In a population in Hardy-Weinberg equilibrium, 9% of individuals show a recessive trait. What percentage of the population is expected to be heterozygous carriers?

Answer: C. 42% — Here q^2 = 0.09, so q = 0.3 and p = 0.7. Carrier frequency = 2pq = 2 × 0.7 × 0.3 = 0.42 or 42%.

BIOLOGY · CLASS 12 SECOND PUC · Karnataka State Board

Practice Chapter 6: Evolution with a free chapter-wise online MCQ test for Karnataka State Board CLASS 12 SECOND PUC BIOLOGY. This chapter covers: Origin of Life Chemical Evolution Natural Selection Darwin Theory Hardy Weinberg Principle Speciation Adaptation Fossils Evolutionary Evidence Genetic Variation. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 6: Evolution — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 12 SECOND PUC BIOLOGY — Chapter 6: Evolution, with answers and explanations. These are sample questions; the exam has its own separate question set.

Who proposed that life originated from pre-existing non-living organic molecules through chemical evolution?

A. Oparin and Haldane ✓
B. Darwin and Wallace
C. Mendel and Morgan
D. Watson and Crick

Answer: A. Oparin and Haldane
Oparin and Haldane suggested that the first life forms arose from pre-existing organic molecules under primitive Earth conditions.

The primitive atmosphere of Earth was mainly:

A. Oxidising and rich in oxygen
B. Reducing and without free oxygen ✓
C. Rich in ozone and nitrogen dioxide
D. Similar to the present atmosphere

Answer: B. Reducing and without free oxygen
According to NCERT, early Earth had a reducing atmosphere containing gases like methane, ammonia, hydrogen and water vapour, with no free oxygen.

Which observation best supports chemical evolution as the origin of life?

A. Spontaneous generation of flies from meat
B. Synthesis of amino acids under simulated primitive Earth conditions ✓
C. Production of oxygen by modern plants
D. Inheritance of acquired characters in giraffes

Answer: B. Synthesis of amino acids under simulated primitive Earth conditions
Miller's experiment showed that organic molecules like amino acids could form under primitive Earth-like conditions.

Two unrelated species living in similar habitats develop similar body forms. This is most likely due to:

A. Divergent evolution
B. Convergent evolution ✓
C. Genetic drift only
D. Founder effect

Answer: B. Convergent evolution
Convergent evolution occurs when unrelated organisms independently evolve similar traits due to similar environmental pressures.

In a population in Hardy-Weinberg equilibrium, 9% of individuals show a recessive trait. What percentage of the population is expected to be heterozygous carriers?