Daily Olympiad: Biology - Genetics Evolution [20260602]

Challenge yourself with today's NEET practice! This test covers 'Genetics Evolution' for Biology (NEET - 11). Level: Hard | Duration: 45 mins.

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1. In a population in Hardy-Weinberg equilibrium, 4% of individuals show a recessive trait. What is the frequency of the dominant allele?

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.

2. Which of the following scenarios best represents directional selection?

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.

3. A population bottleneck occurs when 80% of the individuals in a population are suddenly killed by a natural disaster. Which statement correctly describes the genetic outcome?

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.

4. Which mutation type contributes *least* to evolutionary change at the molecular level?

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.

5. Allopatric speciation is most directly caused by:

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

6. If two populations of a species interbreed occasionally but maintain distinct gene pools due to geographic barriers, this is best described as:

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.

7. In a phylogenetic tree, what does a clade represent?

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.

8. Haldane's rule predicts that when hybrid sterility occurs, it will be manifested in the:

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).

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