Part 6: Gene Flow & Genetic Drift (25 MCQs)
Part 6: Gene Flow & Genetic Drift (25 MCQs)
Q126. Gene flow refers to:
a) Transfer of alleles between populations
b) Mutation in a population
c) Random loss of alleles
d) Natural selection
Answer: a
- a) Correct: Gene flow = movement of alleles between populations due to migration.
Q127. Migration of individuals into a population causes:
a) Loss of genetic variation
b) Introduction of new alleles
c) No change in allele frequencies
d) Extinction
Answer: b
- b) Correct: Migration introduces new alleles and increases variation.
Q128. Migration of individuals out of a population leads to:
a) Increase in allele frequency
b) Decrease in allele frequency
c) No change in allele frequency
d) Speciation
Answer: b
- b) Correct: Emigration reduces allele frequency in source population.
Q129. Continuous gene flow between populations tends to:
a) Increase differences between them
b) Reduce differences between them
c) Cause extinction
d) Stop mutations
Answer: b
- b) Correct: Gene flow homogenizes populations.
Q130. Genetic drift is more significant in:
a) Large populations
b) Small populations
c) Infinite populations
d) Stable populations
Answer: b
- b) Correct: Small populations experience strong drift → random changes.
Q131. Genetic drift is caused by:
a) Chance events
b) Natural selection
c) Non-random mating
d) Mutations only
Answer: a
- a) Correct: Drift occurs due to random sampling of alleles.
Q132. Founder effect is a type of:
a) Gene flow
b) Genetic drift
c) Mutation
d) Selection
Answer: b
- b) Correct: Founder effect = drift in a small group that colonizes new area.
Q133. Bottleneck effect occurs when:
a) Population expands
b) Population size drastically reduces
c) Mutation rate increases
d) Migration occurs
Answer: b
- b) Correct: Bottleneck = sharp reduction in population → allele loss.
Q134. Founder effect leads to:
a) Loss of genetic diversity
b) Increased genetic variation
c) No change in variation
d) Hybrid vigor
Answer: a
- a) Correct: Small founding groups → limited diversity.
Q135. The Amish population showing high incidence of polydactyly is an example of:
a) Mutation
b) Founder effect
c) Bottleneck effect
d) Natural selection
Answer: b
- b) Correct: Amish founded by small group → founder effect.
Q136. The cheetah population shows low genetic diversity due to:
a) Founder effect
b) Bottleneck effect
c) Mutation
d) Gene flow
Answer: b
- b) Correct: Bottleneck effect → drastic population reduction caused inbreeding.
Q137. Genetic drift leads to:
a) Adaptive evolution
b) Non-adaptive random changes
c) Increased mutations
d) Always higher fitness
Answer: b
- b) Correct: Drift = random, non-adaptive allele frequency changes.
Q138. If an allele is lost from a population by chance, it is due to:
a) Mutation
b) Selection
c) Genetic drift
d) Gene flow
Answer: c
- c) Correct: Allele loss by chance = genetic drift.
Q139. Drift results in:
a) Fixation or loss of alleles
b) Increased genetic diversity
c) No change
d) Only beneficial changes
Answer: a
- a) Correct: Drift may cause allele fixation or total loss.
Q140. Which of the following does NOT directly influence genetic drift?
a) Population size
b) Chance events
c) Mutation
d) Random sampling
Answer: c
- c) Correct: Mutation introduces variation, but drift = random allele sampling.
Q141. Gene flow and genetic drift differ because:
a) Gene flow increases variation, drift reduces it
b) Gene flow occurs in large populations, drift in small
c) Drift is random, flow is directional
d) All of the above
Answer: d
- d) Correct: All differences are true.
Q142. Which evolutionary mechanism can counteract genetic drift?
a) Selection
b) Gene flow
c) Mutation
d) All of the above
Answer: d
- d) Correct: Selection, mutation, and migration can balance drift.
Q143. A small isolated population is most affected by:
a) Mutation
b) Selection
c) Genetic drift
d) Gene flow
Answer: c
- c) Correct: Drift strongly affects small isolated populations.
Q144. Which is NOT a consequence of genetic drift?
a) Loss of alleles
b) Fixation of alleles
c) Increase in variation
d) Reduced genetic diversity
Answer: c
- c) Correct: Drift reduces, not increases, variation.
Q145. When alleles become fixed in a population due to drift, the population becomes:
a) More diverse
b) Genetically uniform
c) Less stable
d) Mutated
Answer: b
- b) Correct: Drift → allele fixation → genetic uniformity.
Q146. Which statement is true about genetic drift?
a) It is adaptive
b) It occurs only in large populations
c) It may eliminate alleles randomly
d) It always favors beneficial alleles
Answer: c
- c) Correct: Drift = random, may eliminate alleles regardless of fitness.
Q147. The probability of genetic drift decreases with:
a) Increase in mutation
b) Increase in population size
c) Increase in migration
d) Increase in selection
Answer: b
- b) Correct: Larger populations buffer against drift.
Q148. Which evolutionary mechanism can introduce new alleles into a population?
a) Drift
b) Mutation
c) Selection
d) Fixation
Answer: b
- b) Correct: Mutation introduces new alleles, drift just alters existing ones.
Q149. Founder effect is likely to occur when:
a) Large populations interbreed
b) A small group colonizes a new habitat
c) Mutations spread rapidly
d) Alleles are evenly distributed
Answer: b
- b) Correct: Founder effect = small founder group → limited variation.
Q150. A key difference between gene flow and drift is:
a) Flow homogenizes populations, drift causes divergence
b) Drift increases variation, flow reduces
c) Both increase variation equally
d) Drift is directional, flow is random
Answer: a
- a) Correct: Gene flow reduces differences, drift → random divergence.
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