Question 1

Which of the following best describes Mendel's Law of Segregation?

Accepted Answer

Each individual has two alleles for each gene, and these alleles separate during gamete formation so that each gamete receives only one allele.

Question 2

A pea plant with genotype $Pp$ (where $P$ = purple, $p$ = white) is crossed with a plant with genotype $pp$. What is the expected phenotypic ratio of the offspring?

Accepted Answer

1 purple : 1 white

Question 3

In a dihybrid cross between two heterozygous pea plants ($YyRr 	imes YyRr$), where $Y$ = yellow, $y$ = green, $R$ = round, $r$ = wrinkled, what is the expected phenotypic ratio among the offspring?

Accepted Answer

9 yellow round : 3 yellow wrinkled : 3 green round : 1 green wrinkled

Question 4

Which scenario best illustrates incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered snapdragons produces all pink-flowered offspring.

Question 5

A test cross is performed to determine the genotype of a pea plant with a dominant phenotype. Which cross would you use?

Accepted Answer

Cross the plant with a homozygous recessive individual.

Question 6

Which of the following is an example of codominance?

Accepted Answer

A person with blood type AB expresses both A and B antigens on their red blood cells.

Question 7

If a genetic disorder is autosomal recessive, which of the following must be true for an individual to express the disorder?

Accepted Answer

The individual must inherit two copies of the recessive allele.

Question 8

Which of the following best explains polygenic inheritance?

Accepted Answer

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

Question 9

A man with genotype $I^A I^O$ (blood type A) and a woman with genotype $I^B I^O$ (blood type B) have a child. Which blood type is NOT possible for their child?

Accepted Answer

None of the above; all are possible.

Question 10

Which of the following is an example of epistasis?

Accepted Answer

A gene that determines whether pigment is deposited in hair, regardless of the gene for hair color.

Question 11

In a pedigree, a trait appears in every generation and affected individuals have at least one affected parent. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 12

A woman who is a carrier for cystic fibrosis ($Ff$) and a man who is also a carrier ($Ff$) have a child. What is the probability that the child will have cystic fibrosis?

Accepted Answer

$\frac{1}{4}$

Question 13

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

Accepted Answer

Genotype is the genetic makeup, while phenotype is the physical appearance.

Question 14

A plant with genotype $AaBb$ is self-crossed. What is the probability that an offspring will be homozygous recessive for both traits?

Accepted Answer

$\frac{1}{16}$

Question 15

Which of the following is NOT a reason Mendel chose pea plants for his experiments?

Accepted Answer

They have a long generation time.

Question 16

A man with Huntington's disease (autosomal dominant) has a child with a woman who does not have the disease. What is the probability that their child will inherit the disease if the man is heterozygous?

Accepted Answer

$\frac{1}{2}$

Question 17

Which of the following best explains the Law of Independent Assortment?

Accepted Answer

Alleles of different genes assort independently of one another during gamete formation.

Question 18

A couple has three children, all with different skin tones, despite having the same parents. Which genetic principle best explains this observation?

Accepted Answer

Polygenic inheritance

Question 19

Which of the following is a real-world example of environmental influence on phenotype?

Accepted Answer

Hydrangea flowers changing color depending on soil pH.

Question 20

A woman with genotype $Dd$ (where $D$ = normal hearing, $d$ = deafness) and a man with genotype $Dd$ have a child. What is the probability that the child will be a carrier but have normal hearing?

Accepted Answer

$\frac{1}{2}$

Mendelian Genetics: Principles, Patterns, and Extensions

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