Question 1

Which of the following best describes Mendel's 'particulate' hypothesis of inheritance?

Accepted Answer

Parents pass on discrete heritable units that retain their identity in offspring.

Question 2

In a cross between two heterozygous pea plants for flower color (Pp x Pp), what is the probability that an offspring will have white flowers? Use the multiplication rule to justify your answer.

Accepted Answer

$$\frac{1}{4}$$

Question 3

Which of the following statements about dominant alleles is correct?

Accepted Answer

Dominant alleles mask the effects of recessive alleles in heterozygotes.

Question 4

A man with type AB blood and a woman with type O blood have a child. What are the possible blood types for their child?

Accepted Answer

Type A or Type B

Question 5

Which of the following best explains the law of independent assortment?

Accepted Answer

Each pair of alleles segregates independently of other pairs during gamete formation.

Question 6

A genetic counselor is working with a couple, both of whom are carriers for cystic fibrosis (a recessive disorder). What is the probability that their first two children will both have cystic fibrosis?

Accepted Answer

$$\frac{1}{16}$$

Question 7

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene affecting multiple symptoms of sickle-cell disease.

Question 8

In Labrador retrievers, coat color is determined by two genes: one for pigment color (B = black, b = brown) and one for pigment deposition (E = color, e = no color). What is the expected phenotypic ratio in the offspring of a BbEe x BbEe cross?

Accepted Answer

9 black : 3 brown : 4 yellow

Question 9

Which of the following best describes a testcross?

Accepted Answer

Breeding an individual with the dominant phenotype with a homozygous recessive individual to determine genotype.

Question 10

A woman who is a carrier for sickle-cell disease (Ss) marries a man who is also a carrier (Ss). What is the probability that their child will be phenotypically normal and not a carrier?

Accepted Answer

$$\frac{1}{4}$$

Question 11

Which of the following is an example of incomplete dominance?

Accepted Answer

A red-flowered plant crossed with a white-flowered plant produces pink-flowered offspring.

Question 12

Which of the following statements about multifactorial traits is correct?

Accepted Answer

They are influenced by both genetic and environmental factors.

Question 13

If a trait is controlled by polygenic inheritance, which of the following patterns would you expect to see in a population?

Accepted Answer

A continuous range of phenotypes, such as human skin color.

Question 14

Which of the following best explains why consanguineous matings increase the risk of recessive genetic disorders?

Accepted Answer

Close relatives are more likely to carry the same rare recessive alleles.

Question 15

A couple has a child with cystic fibrosis, a recessive disorder. Neither parent has the disease. What are the genotypes of the parents?

Accepted Answer

Both are heterozygous carriers.

Question 16

Which of the following is true regarding codominance?

Accepted Answer

Both alleles are fully expressed in the phenotype.

Question 17

A woman with attached earlobes (recessive trait) and a man with free earlobes (dominant trait) have a child with attached earlobes. What is the genotype of the man?

Accepted Answer

Heterozygous

Question 18

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

The genotype determines the phenotype, but the environment can also influence the phenotype.

Question 19

In a dihybrid cross between two individuals heterozygous for both traits (YyRr x YyRr), what is the probability of obtaining an offspring with the genotype yyrr?

Accepted Answer

$$\frac{1}{16}$$

Question 20

Which of the following is a reason why humans are not ideal subjects for Mendelian genetic experiments?

Accepted Answer

Humans have long generation times and produce relatively few offspring.

Mendelian Genetics: Principles of Heredity and Patterns of Inheritance

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