CLEP Biology Mendelian Inheritance Patterns 2

Question 1

In a dihybrid cross between two heterozygous parents (AaBb × AaBb), what fraction of offspring are expected to be homozygous recessive for both traits (aabb)?

Accepted Answer

1/16

Answer

Each trait independently produces 1/4 homozygous recessive offspring, so (1/4)(1/4) = 1/16 for both.

Question 2

A man with blood type A (genotype I^A i) and a woman with blood type B (genotype I^B i) have children. What is the probability that a child will have blood type O?

Accepted Answer

1/4

Answer

The cross I^A i × I^B i produces I^A I^B, I^A i, I^B i, and ii in equal 1/4 proportions, so 1/4 will be type O.

Question 3

Which of the following best describes the concept of 'gene interaction' in the context of epistasis?

Accepted Answer

One gene masks or modifies the expression of another gene

Answer

Epistasis occurs when one gene's alleles suppress or alter the phenotypic expression of a different gene.

Question 4

A plant with red flowers (RR) is crossed with a white-flowered plant (rr), producing all pink offspring (Rr). This pattern of inheritance is an example of:

Accepted Answer

Incomplete dominance

Answer

Incomplete dominance produces an intermediate phenotype (pink) because neither allele is fully dominant over the other.

Question 5

In humans, the allele for attached earlobes (a) is recessive to free earlobes (A). Two parents with free earlobes have a child with attached earlobes. What are the genotypes of the parents?

Accepted Answer

Aa × Aa

Answer

Both parents must be Aa (carriers) to produce an aa child while themselves expressing the dominant phenotype.

CLEP Practice Test

CLEP Practice Test

CLEP Biology Mendelian Inheritance Patterns 2