CLEP Biology Mendelian Inheritance Patterns 4

Question 1

A trait appears in every generation of a pedigree and affects both males and females equally. Affected individuals always have at least one affected parent. This pattern is most consistent with:

Accepted Answer

Autosomal dominant inheritance

Answer

Autosomal dominant traits appear in every generation (no skipping), affect both sexes equally, and require only one dominant allele.

Question 2

In Labrador retrievers, coat color is controlled by two genes: E (extension) and B (brown). A dog with genotype B_E_ is black, B_ee is yellow, bbE_ is chocolate, and bbee is yellow. This is an example of:

Accepted Answer

Recessive epistasis

Answer

The ee genotype masks the B locus entirely, causing yellow regardless of the B allele — this is recessive epistasis.

Question 3

If the frequency of an autosomal recessive disease in a population is 1/10,000, what is the approximate carrier frequency according to the Hardy-Weinberg principle?

Accepted Answer

1/50

Answer

q² = 1/10,000 so q = 1/100; carrier frequency = 2pq ≈ 2(1)(1/100) = 1/50.

Question 4

A cross between a black chicken (BB) and a white chicken (bb) produces all blue-grey (splash) offspring. When two splash chickens are crossed, the expected offspring ratio is:

Accepted Answer

1 black : 2 blue-grey : 1 white

Answer

Incomplete dominance: Bb (splash) × Bb gives 1 BB (black) : 2 Bb (splash) : 1 bb (white).

Question 5

Pleiotropy refers to a situation in which:

Accepted Answer

A single gene influences multiple, seemingly unrelated phenotypic traits

Answer

Pleiotropy occurs when one gene has multiple phenotypic effects, as seen with PKU affecting brain, skin, and hair pigmentation.

CLEP Practice Test

CLEP Practice Test

CLEP Biology Mendelian Inheritance Patterns 4