Question 1

Which of the following best describes the inheritance pattern of the ABO blood group system in humans?

Accepted Answer

It is an example of codominance, where both A and B alleles are fully expressed in heterozygotes.

Question 2

A woman with type AB blood and a man with type O blood have a child. What are the possible blood types of their child? Use the following alleles: $$I^A$$, $$I^B$$, and $$i.$$

Accepted Answer

Type A or Type B

Question 3

Which of the following is an example of pleiotropy in humans?

Accepted Answer

Cystic fibrosis, where a single gene affects multiple organ systems

Question 4

A geneticist is analyzing a pedigree for a rare disorder. The disorder appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 5

Which of the following best describes epistasis?

Accepted Answer

One gene masks or modifies the expression of another gene at a different locus

Question 6

A child is born with Down syndrome. Which chromosomal abnormality is most likely responsible for this condition?

Accepted Answer

Trisomy 21, resulting from nondisjunction during meiosis

Question 7

Which of the following best explains why X-linked recessive diseases are more common in males than in females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will cause the disease.

Question 8

Which of the following is a correct statement about polygenic inheritance?

Accepted Answer

It involves multiple genes contributing additively to a single trait, such as human height.

Question 9

A karyotype is prepared for a patient. The karyotype shows 47 chromosomes, including two X chromosomes and one Y chromosome. Which syndrome does this individual most likely have?

Accepted Answer

Klinefelter syndrome

Question 10

Which of the following best describes an inborn error of metabolism?

Accepted Answer

A genetic disorder caused by a mutation affecting an enzyme in a metabolic pathway, such as phenylketonuria (PKU)

Question 11

Which of the following is true regarding dosage compensation in mammals?

Accepted Answer

One X chromosome in each female cell is inactivated, forming a Barr body.

Question 12

A woman who is a carrier for an X-linked recessive disorder and a man who is unaffected have a son. What is the probability that their son will have the disorder?

Accepted Answer

$$50\%$$

Question 13

Which of the following best describes a multifactorial trait?

Accepted Answer

A trait influenced by both genetic and environmental factors, such as heart disease risk

Question 14

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

Accepted Answer

A cross between a red-flowered and a white-flowered snapdragon produces pink-flowered offspring.

Question 15

Which of the following best describes the role of the SRY gene in humans?

Accepted Answer

It triggers male development by initiating testis formation on the Y chromosome.

Question 16

A pedigree shows a trait that skips generations and is more common in males. What is the most likely mode of inheritance?

Accepted Answer

X-linked recessive

Question 17

Which of the following is a consequence of nondisjunction during meiosis?

Accepted Answer

Aneuploidy, such as trisomy or monosomy

Question 18

Which of the following is NOT a sex chromosome abnormality?

Accepted Answer

Trisomy 21 (Down syndrome)

Question 19

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the heterozygote, as seen in the MN blood group.

Question 20

Which of the following statements about autosomes is correct?

Accepted Answer

They are chromosomes that are not involved in determining sex.

Patterns of Inheritance: Key Concepts and Applications

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