Question 1

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

Accepted Answer

Two alleles for a heritable character separate during gamete formation and end up in different gametes.

Question 2

A pea plant with genotype $$Pp is $$crossed with another $$Pp$$ plant. What is the expected phenotypic ratio of their offspring?

Accepted Answer

$$3:1 ($$three purple, one white)

Question 3

In a testcross, a plant with the dominant phenotype is crossed with a homozygous recessive plant. If any offspring display the recessive phenotype, what can you conclude about the genotype of the parent with the dominant phenotype?

Accepted Answer

It must be heterozygous.

Question 4

Which of the following is an example of incomplete dominance?

Accepted Answer

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

Question 5

A man with blood type AB marries a woman with blood type O. What are the possible blood types of their children?

Accepted Answer

A or B

Question 6

Which of the following best illustrates pleiotropy?

Accepted Answer

A single gene mutation causing blindness, liver failure, and heart attack in sickle-cell disease.

Question 7

In Labrador retrievers, coat color is determined by two genes. One gene determines pigment color (B = black, b = brown), and another gene determines whether pigment is deposited (E = pigment, e = no pigment). What is the expected phenotypic ratio in the offspring of two dihybrid dogs ($$BbEe 	imes BbEe$$)?

Accepted Answer

$$9:3:4 ($$black:brown:yellow)

Question 8

Which of the following statements about polygenic inheritance is correct?

Accepted Answer

It produces quantitative variation, such as human height, due to the additive effect of two or more genes.

Question 9

A woman who is a carrier for albinism ($$Aa) $$marries a man who is also a carrier ($$Aa). $$What is the probability that their child will have albinism?

Accepted Answer

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

Question 10

Which of the following best explains why Huntington’s disease persists in human populations despite being caused by a dominant allele?

Accepted Answer

Symptoms do not appear until after reproductive age, allowing carriers to pass on the allele.

Question 11

If a plant with genotype $$Pp ($$purple flowers) is self-pollinated, what is the probability that an offspring will be homozygous for the dominant allele?

Accepted Answer

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

Question 12

Which of the following scenarios demonstrates codominance?

Accepted Answer

A person with genotype $$IAIB$$ expresses both A and B antigens on their red blood cells.

Question 13

Which of the following is NOT a reason why humans are poor subjects for genetic research compared to pea plants?

Accepted Answer

Humans have only one allele for each gene.

Question 14

A true-breeding yellow-seeded pea plant ($$YY) is $$crossed with a true-breeding green-seeded pea plant ($$yy). $$What will be the genotype and phenotype of the F1 generation?

Accepted Answer

All $$Yy$$, all yellow

Question 15

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

Accepted Answer

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

Question 16

A geneticist is studying a trait controlled by a single gene with two alleles. If the dominant allele is not completely dominant over the recessive allele, what type of inheritance pattern is this?

Accepted Answer

Incomplete dominance

Question 17

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment deposition in Labrador retrievers masking the effect of the pigment color gene.

Question 18

If two individuals with the genotype $$AaBbCc ($$for three independently assorting genes) are crossed, what is the probability that an offspring will be homozygous recessive for all three genes?

Accepted Answer

$$\frac{1}{64}$$

Question 19

Which of the following best describes a carrier for a recessively inherited disorder?

Accepted Answer

An individual who is heterozygous and does not show symptoms but can pass the allele to offspring.

Mendel and the Gene Idea: Foundations of Classical Genetics

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