Question 1

Which of the following statements best describes the inheritance pattern of mitochondrial diseases in humans?

Accepted Answer

They are inherited exclusively from the mother, regardless of the sex of the offspring.

Question 2

A couple, both phenotypically normal, have a child with cystic fibrosis, an autosomal recessive disorder. What is the probability that their next child will also have cystic fibrosis?

Accepted Answer

$$25\%$$

Question 3

Which of the following best explains why oncogenes are typically dominant in their action, while tumor-suppressor genes are recessive?

Accepted Answer

A single mutated oncogene allele can drive excessive cell proliferation, but both tumor-suppressor alleles must be inactivated to lose cell cycle control.

Question 4

A man with an X-linked recessive disorder marries a woman who is a carrier. What is the probability that their son will be affected?

Accepted Answer

$$50\%$$

Question 5

Which of the following is a key feature of Y-linked inheritance?

Accepted Answer

Only males are affected, and all sons of an affected father will be affected.

Question 6

A woman with normal pigmentation has a child with albinism (an autosomal recessive trait). Her husband also has normal pigmentation. What are the possible genotypes of the parents?

Accepted Answer

Both parents must be heterozygous.

Question 7

Which of the following human traits is most likely to be polygenic?

Accepted Answer

Height

Question 8

In a testcross, an individual with a dominant phenotype but unknown genotype is crossed with which of the following?

Accepted Answer

A homozygous recessive individual

Question 9

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

Accepted Answer

Alleles of genes on nonhomologous chromosomes assort independently during gamete formation.

Question 10

A pedigree shows a trait that appears in every generation, affects both sexes equally, and all affected individuals have at least one affected parent. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 11

A woman with a mitochondrial disorder has children with a healthy man. What is the probability that her daughters will inherit the disorder?

Accepted Answer

$$100\%$$

Question 12

Which of the following is NOT a characteristic of a good model genetic organism?

Accepted Answer

Long lifespan and slow reproduction

Question 13

A genetic counselor explains to a couple that their child has Tay-Sachs disease, an autosomal recessive disorder. Neither parent is affected. What is the probability that their next child will also have Tay-Sachs disease?

Accepted Answer

$$25\%$$

Question 14

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute additively to a single phenotype.

Question 15

Which of the following is true about X-linked dominant inheritance?

Accepted Answer

Affected fathers pass the trait to all their daughters but none of their sons.

Question 16

A woman who is heterozygous for an X-linked recessive disorder has children with a normal man. What is the probability that their daughter will be a carrier?

Accepted Answer

$$50\%$$

Question 17

Which of the following is a common feature of autosomal recessive inheritance?

Accepted Answer

Affected offspring are usually born to unaffected carrier parents.

Question 18

Which of the following diseases is an example of a polygenic, multifactorial disease?

Accepted Answer

Type 2 diabetes

Question 19

Which of the following statements about pedigree analysis is correct?

Accepted Answer

It is used to study inheritance patterns in humans by analyzing family history.

Question 20

Which of the following best describes the difference between forward and reverse genetics?

Accepted Answer

Forward genetics starts with a phenotype and identifies the gene; reverse genetics starts with a gene and studies the phenotype after altering it.

Mendelian and Non-Mendelian Genetics & Human Disease: Study Guide

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