Multiple Choice Questions With Answers &
Rationales 2025-2026 Updates
Q1. Which of the following best describes natural selection?
A) Random changes in allele frequencies
B) Differential survival and reproduction of individuals
C) Movement of genes between populations
D) Mutation introducing new alleles
Answer: B
Rationale: Natural selection favors individuals with traits that increase fitness, changing allele frequencies over
time.
Q2. A population of lizards is separated by a newly formed river. Over time, they evolve into two species. This
is:
A) Sympatric speciation
B) Allopatric speciation
C) Genetic drift
D) Artificial selection
Answer: B
Rationale: Geographic isolation leads to allopatric speciation.
Q3. Which describes the maximum number of individuals an environment can support?
A) Birth rate
B) Carrying capacity
C) Logistic growth
D) Exponential growth
Answer: B
Rationale: Carrying capacity (K) is the sustainable population size based on resources.
Q4. A population crash due to overpopulation and food shortage is most associated with:
,A) Logistic growth
B) Exponential growth
C) Density-independent regulation
D) Survivorship curve
Answer: A
Rationale: Logistic growth considers resource limits; overshoot leads to population crashes.
Q5. Which interaction is mutualistic?
A) Tick feeding on deer
B) Barnacles on a whale
C) Bees pollinating flowers
D) Lion hunting zebra
Answer: C
Rationale: Both bees and flowers benefit.
Q6. Which biome has permafrost and low biodiversity?
A) Desert
B) Tundra
C) Temperate forest
D) Savanna
Answer: B
Rationale: Tundra has permanently frozen ground and extreme conditions.
Q7. The Hardy-Weinberg principle assumes all EXCEPT:
A) Random mating
B) Large population size
C) No gene flow
D) Natural selection present
Answer: D
Rationale: Hardy-Weinberg assumes no natural selection.
, Q8. Which describes genetic drift?
A) Random changes in allele frequencies in small populations
B) Transfer of alleles between populations
C) Nonrandom mating
D) Mutations always beneficial
Answer: A
Rationale: Drift occurs by chance, especially in small populations.
Q9. Which survivorship curve best represents humans in developed countries?
A) Type I
B) Type II
C) Type III
D) Logistic
Answer: A
Rationale: Type I shows high survival early, with mortality increasing at old age.
Q10. A sudden volcanic eruption wipes out most of a population, regardless of fitness. This is:
A) Founder effect
B) Bottleneck effect
C) Gene flow
D) Selection
Answer: B
Rationale: The bottleneck effect reduces diversity due to random survival.
Q11. An allele provides no advantage or disadvantage. Its frequency changes due to chance. This is:
A) Gene flow
B) Genetic drift
C) Natural selection
D) Mutation
Answer: B
Rationale: Drift, not selection, causes random shifts in allele frequency.