OAT Genetics and Evolution 2

Question 1

In incomplete dominance, two homozygous parents (red × white flowers) produce offspring with pink flowers. When the pink offspring are crossed together, what phenotypic ratio is expected in the F2 generation?

Accepted Answer

1 red : 2 pink : 1 white

Answer

Crossing heterozygotes (Rr × Rr) in an incomplete dominance system yields 1 RR (red) : 2 Rr (pink) : 1 rr (white) because neither allele fully masks the other.

Question 2

Which of the following best describes epistasis?

Accepted Answer

One gene's alleles masking or modifying the expression of a different gene

Answer

Epistasis occurs when the alleles at one gene locus affect the phenotypic expression of a separate gene locus, altering expected Mendelian ratios.

Question 3

What is the Hardy-Weinberg equation used to calculate?

Accepted Answer

The expected allele and genotype frequencies in a non-evolving population

Answer

The Hardy-Weinberg equation (p² + 2pq + q² = 1) predicts genotype frequencies under the assumption of no evolution (no selection, drift, gene flow, or mutation).

Question 4

Sickle cell anemia is an autosomal recessive disorder. Two carriers have children together. What fraction of their children would be expected to be carriers but unaffected?

Accepted Answer

1/2

Answer

A cross between two carriers (Aa × Aa) yields 1/4 AA : 2/4 Aa : 1/4 aa; exactly half (2/4) of the offspring are expected to be carriers (Aa) and phenotypically unaffected.

Question 5

Which process generates the greatest genetic diversity during sexual reproduction?

Accepted Answer

Independent assortment and crossing over during meiosis

Answer

Independent assortment and crossing over during meiosis shuffle alleles into new combinations, producing gametes with unique genetic compositions that drive diversity.

OAT - Optometry Admission Test Practice Test

OAT - Optometry Admission Test Practice Test

OAT Genetics and Evolution 2