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 $$Pp ($$purple flowers) is crossed with a plant with genotype $$pp ($$white flowers). What is the expected phenotypic ratio of the offspring?

Accepted Answer

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

Question 3

Which scenario is an example of incomplete dominance?

Accepted Answer

A cross between red and white snapdragons produces pink offspring.

Question 4

A genetic counselor is working with a couple, both of whom are carriers for cystic fibrosis ($$Ff). $$What is the probability that their child will have cystic fibrosis?

Accepted Answer

$$1/4$$

Question 5

Which of the following best explains why sickle-cell disease is considered pleiotropic?

Accepted Answer

It affects multiple organ systems due to a single gene mutation.

Question 6

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 7

Which of the following is an example of codominance?

Accepted Answer

A person with type AB blood expresses both A and B antigens equally.

Question 8

A man with achondroplasia (dwarfism, genotype $$Dd) $$and a woman of normal stature ($$dd) $$have a child. What is the probability that the child will have achondroplasia?

Accepted Answer

$$1/2$$

Question 9

Which of the following best describes polygenic inheritance?

Accepted Answer

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

Question 10

A couple undergoes preimplantation genetic diagnosis (PGD) during IVF. What is the main purpose of this procedure?

Accepted Answer

To select embryos free of specific genetic diseases before implantation.

Question 11

Which of the following is an example of epistasis?

Accepted Answer

The gene for pigment deposition in Labrador retrievers masks the gene for coat color.

Question 12

If a heterozygous individual ($$Pp) is $$testcrossed with a homozygous recessive ($$pp$$), what is the expected genotypic ratio of the offspring?

Accepted Answer

$$1 Pp$$ : $$1 pp$$

Question 13

Which of the following statements about cystic fibrosis is correct?

Accepted Answer

It is the most common lethal genetic disease in the United States.

Question 14

A woman with genotype $$IAIB$$ and a man with genotype $$ii$$ have a child. What are the possible blood types of their child?

Accepted Answer

A or B

Question 15

Which of the following best explains why heterozygotes for sickle-cell disease are more common in malaria-endemic regions?

Accepted Answer

Heterozygotes are resistant to malaria.

Question 16

Which of the following is NOT a feature of Mendel's particulate hypothesis?

Accepted Answer

Traits blend together in the offspring.

Question 17

A child is born with phenylketonuria (PKU), a recessive disorder. Both parents are healthy. What is the probability that their next child will also have PKU?

Accepted Answer

$$1/4$$

Question 18

Which of the following best describes the effect of environment on phenotype?

Accepted Answer

Environmental factors such as temperature and nutrition can influence the expression of genetic traits.

Question 19

Which of the following is a real-life example of a testcross?

Accepted Answer

Crossing a purple-flowered pea plant of unknown genotype with a white-flowered plant to determine if the purple plant is homozygous or heterozygous.

Mendel and the Gene Idea: Patterns and Extensions of Inheritance chptr. 14

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