Daily Olympiad: Biology - Genetics Evolution [20260602]

Solution

Correct: B

Using the Hardy-Weinberg equation (q² = 0.04 → q = 0.2). The dominant allele frequency is 1 - q = 0.8 → p² + 2pq = 0.8² + 2*(0.8*0.2) = 0.64 + 0.32 = 0.96. However, the question asks for the dominant allele frequency directly, which is 0.8.

Solution

Correct: A

Directional selection favors one extreme phenotype. The peppered moth case directly selects for darker moths under pollution, shifting allele frequencies toward the dark allele. Other options represent stabilizing or neutral selection.

Solution

Correct: A

A bottleneck reduces population size drastically, causing strong genetic drift as random allele frequencies dominate. New mutations take generations to occur, and gene flow is unlikely in the immediate aftermath.

Solution

Correct: A

Silent mutations do not alter the amino acid sequence and hence have minimal impact on protein function or fitness. They contribute minimally to evolutionary change compared to mutations causing nonfunctional proteins or altered amino acids.

Solution

Correct: B

Allopatric speciation occurs when populations are physically separated (geographic isolation). Gene flow cessation allows independent evolutionary changes, leading to reproductive isolation.

Solution

Correct: A

Parapatric speciation involves partially overlapping populations with limited gene flow due to geographic gradients. Peripatric is a subset of allopatric with small isolated populations. Sympatric requires no geographic separation.

Solution

Correct: A

A clade is a monophyletic group (all descendants of a common ancestor). Clades exclude paraphyletic or polyphyletic groups. Convergent evolution forms analogous traits, not clades.

Solution

Correct: C

Haldane's rule states that hybrid sterility is more common in the heterogametic sex (e.g., XY males in mammals, ZW females in birds due to the Z chromosome's role in gamete production).