Question 1

Which of the following best explains why haploid cells may undergo mitosis but not meiosis?

Accepted Answer

Homologous chromosomes cannot pair.

Question 2

In Mendel's pea plant experiments, what is the expected phenotypic ratio in the F2 generation when crossing two heterozygous purple-flowered plants ($$Pp 	imes Pp$$)?

Accepted Answer

$$3$$ purple : $$1$$ white

Question 3

Which of the following statements about dominant alleles is correct?

Accepted Answer

Dominant alleles are not necessarily more frequent in a population than recessive alleles.

Question 4

A plant with genotype $$TtAa ($$tall stems, axial flowers) is crossed with a plant with genotype $$ttaa ($$dwarf stems, terminal flowers). What is the expected proportion of offspring with tall stems and terminal flowers?

Accepted Answer

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

Question 5

Which law states that alleles for different traits segregate independently during gamete formation?

Accepted Answer

Law of Independent Assortment

Question 6

In a cross between $$AaBb 	imes AaBb$$, what is the probability of obtaining an offspring with genotype $$aabb$$?

Accepted Answer

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

Question 7

Which of the following is an example of pleiotropy?

Accepted Answer

A gene that causes multiple symptoms in sickle-cell disease.

Question 8

A couple, both carriers for a recessive genetic disorder, want to know the probability that their child will inherit the disorder. What is the probability?

Accepted Answer

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

Question 9

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote phenotype is intermediate between the two homozygotes.

Question 10

In Tay-Sachs disease, which statement is true regarding the relationship between genotype and phenotype?

Accepted Answer

At the molecular level, the alleles are codominant.

Question 11

If a true-breeding red-flowered plant ($$RR) is $$crossed with a true-breeding white-flowered plant ($$rr$$), and the F1 generation all have pink flowers, what type of inheritance is this?

Accepted Answer

Incomplete dominance

Question 12

Which of the following is true about normal gametes produced from one meiotic event?

Accepted Answer

They each have the same chromosome number.

Question 13

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

Accepted Answer

A or B

Question 14

Which of the following is an example of polygenic inheritance?

Accepted Answer

Height in humans

Question 15

In a dihybrid cross ($$YyRr 	imes YyRr$$), what is the probability of obtaining an offspring with genotype $$YYRR$$?

Accepted Answer

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

Question 16

Which of the following best describes a testcross?

Accepted Answer

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

Question 17

Which of the following is true about the law of segregation?

Accepted Answer

It states that two alleles for a heritable character separate during gamete formation.

Question 18

A genetic counselor is working with a couple, both of whom have a sibling affected by a recessive disorder. If neither parent is affected, what is the probability that both are carriers?

Accepted Answer

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

Question 19

Which of the following is an example of epistasis?

Accepted Answer

A gene that masks the expression of another gene at a different locus.

Question 20

If a plant with genotype $$PpYyRr is $$crossed with a plant with genotype $$Ppyyrr$$, what is the probability that an offspring will have the genotype $$ppyyrr$$?

Accepted Answer

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

Mendelian Genetics: Principles, Patterns, and Extensions

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