Question 1

Which of the following best explains why Mendel chose pea plants for his experiments on inheritance?

Accepted Answer

Pea plants have many distinct varieties, short generation times, and their mating can be controlled.

Question 2

A pea plant with genotype Pp is crossed with another plant of genotype Pp. What is the probability that an offspring will have white flowers? (Assume P = purple, p = white)

Accepted Answer

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

Question 3

Which statement best describes the law of segregation as discovered by Mendel?

Accepted Answer

Alleles for a heritable character separate during gamete formation, so each gamete receives only one allele.

Question 4

A testcross is performed between a pea plant with purple flowers of unknown genotype and a white-flowered plant. If all offspring have purple flowers, what is the genotype of the purple-flowered parent?

Accepted Answer

Homozygous dominant (PP)

Question 5

In a dihybrid cross between two heterozygous pea plants (YyRr × YyRr), what is the probability of obtaining an offspring with yellow round seeds (dominant for both traits)?

Accepted Answer

$$\frac{9}{16}$$

Question 6

Which of the following scenarios is an example of incomplete dominance?

Accepted Answer

A cross between red and white snapdragons produces pink flowers.

Question 7

A woman with blood type A (genotype IAi) and a man with blood type B (genotype IBi) have a child. What is the probability that their child will have type O blood?

Accepted Answer

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

Question 8

Which of the following best illustrates pleiotropy?

Accepted Answer

A single gene affects both eye color and susceptibility to a disease.

Question 9

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 F2 generation from a cross of BbEe × BbEe?

Accepted Answer

9 black : 3 chocolate : 4 yellow

Question 10

A couple, both of whom had a sibling with a recessive genetic disorder, want to know the probability that their child will have the disorder. If neither parent nor their partners are affected, what is the probability their child will have the disorder?

Accepted Answer

$$\frac{1}{9}$$

Question 11

Which of the following is an example of a multifactorial disorder?

Accepted Answer

Heart disease

Question 12

Why are dominant alleles not necessarily more common than recessive alleles in a population?

Accepted Answer

Frequency of an allele depends on evolutionary factors, not dominance.

Question 13

A genetic counselor is working with a couple where both are carriers for cystic fibrosis (a recessive disorder). What is the probability that their first child will be a carrier but not affected?

Accepted Answer

$$\frac{1}{2}$$

Question 14

Which of the following best describes codominance?

Accepted Answer

Both alleles in a heterozygote are fully expressed in the phenotype.

Question 15

A man with achondroplasia (a dominant disorder) and a woman without the disorder have a child. What is the probability that the child will have achondroplasia if the man is heterozygous?

Accepted Answer

$$\frac{1}{2}$$

Question 16

Which of the following best explains why sickle-cell disease is more common in certain populations?

Accepted Answer

Heterozygotes have a selective advantage in regions where malaria is common.

Question 17

Which of the following is true regarding polygenic inheritance?

Accepted Answer

Multiple genes independently contribute to a single trait, resulting in continuous variation.

Question 18

If a trait is determined by both genetic and environmental factors, it is best described as:

Accepted Answer

Multifactorial

Question 19

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

Accepted Answer

Phenotype results from the interaction of genotype and environment.

Question 20

A woman is a carrier for a recessive X-linked disorder. If she has a child with a man who does not have the disorder, what is the probability that their son will have the disorder?

Accepted Answer

$$\frac{1}{2}$$

Mendelian Genetics and Extensions: Principles of Heredity and Human Genetic Disorders

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