CLEP - Biology Mendelian Inheritance Patterns Questions and Answers

Question 1

Mendel's Law of Segregation states that during the formation of gametes, the two alleles for a heritable character:

Accepted Answer

separate from each other, so that each gamete ends up with only one allele.

Answer

Mendel's Law of Segregation explains that for any given trait, the pair of alleles from each parent separate and only one allele is passed from each parent to an offspring. This ensures that each gamete (sperm or egg) carries only one allele for each gene.

Question 2

In a dihybrid cross between two heterozygous individuals (e.g., RrYy x RrYy), what is the expected phenotypic ratio of the offspring, assuming complete dominance and independent assortment?

Accepted Answer

9:3:3:1

Answer

A dihybrid cross involving two traits where both parents are heterozygous results in a characteristic 9:3:3:1 phenotypic ratio. This ratio represents the four possible combinations of the two different phenotypes: 9/16 will show both dominant traits, 3/16 will show the first dominant and second recessive trait, 3/16 will show the first recessive and second dominant trait, and 1/16 will show both recessive traits.

Question 3

A cross between a red-flowered snapdragon (RR) and a white-flowered snapdragon (WW) produces all pink-flowered offspring (RW). This pattern of inheritance is known as:

Accepted Answer

Incomplete dominance

Answer

This scenario is a classic example of incomplete dominance, where the heterozygous phenotype is an intermediate blend of the two homozygous phenotypes. Neither the red nor the white allele is completely dominant, resulting in a pink appearance.

Question 4

Which of the following is a key characteristic of an autosomal recessive inheritance pattern?

Accepted Answer

The trait can skip generations, and affected offspring can have unaffected parents.

Answer

In autosomal recessive inheritance, an individual must inherit two copies of the recessive allele to express the trait. Unaffected parents can both be heterozygous carriers and pass the recessive allele to their offspring, causing the trait to 'skip' a generation. The trait affects males and females with equal probability.

Question 5

In humans, red-green color blindness is an X-linked recessive trait. If a colorblind man marries a woman who is a carrier for the trait, what is the probability that their son will be colorblind?

Accepted Answer

50%

Answer

A son inherits his X chromosome from his mother and his Y chromosome from his father. Since the mother is a carrier (heterozygous), she has one X chromosome with the normal allele and one with the colorblind allele. Therefore, there is a 50% chance she will pass the X chromosome with the colorblind allele to her son, making him colorblind.

CLEP Practice Test

CLEP Practice Test

CLEP - Biology Mendelian Inheritance Patterns Questions and Answers