Question 1

Which of the following best explains why Mendel chose pea plants for his experiments on heredity?

Accepted Answer

Pea plants have easily distinguishable traits and can be cross-pollinated or self-pollinated.

Question 2

According to the chromosome theory of inheritance, what is the relationship between genes and chromosomes?

Accepted Answer

Each gene is located at a specific locus on a chromosome.

Question 3

In Morgan's experiments with Drosophila, what was the significance of discovering white-eyed male flies in the F2 generation?

Accepted Answer

It provided evidence that genes are located on sex chromosomes.

Question 4

Which of the following best describes the law of independent assortment as illustrated by Mendel's dihybrid crosses?

Accepted Answer

Alleles for different genes assort independently of one another during gamete formation.

Question 5

A woman who is heterozygous for an X-linked recessive disorder has children with a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

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

Question 6

Which of the following statements about X-inactivation in female mammals is correct?

Accepted Answer

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

Question 7

If two genes are located very close together on the same chromosome, what is the expected recombination frequency between them?

Accepted Answer

Close to 0%

Question 8

A geneticist observes a recombination frequency of 12% between two genes. How many map units apart are these genes?

Accepted Answer

$$12$$ map units

Question 9

Which chromosomal abnormality is most likely to result from non-disjunction during meiosis?

Accepted Answer

Aneuploidy

Question 10

A child is born with cri du chat syndrome, which is caused by a deletion on chromosome 5. What type of chromosomal alteration is this?

Accepted Answer

Deletion

Question 11

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

Accepted Answer

Males only need one copy of the recessive allele to express the disorder.

Question 12

Which of the following is an example of a disorder caused by a translocation between chromosomes?

Accepted Answer

Chronic myelogenous leukemia (CML)

Question 13

A plant with genotype $$YyRr is $$crossed with a plant with genotype $$yyrr. $$What is the expected phenotypic ratio of the offspring if the genes assort independently?

Accepted Answer

1:1:1:1

Question 14

Which of the following best describes genomic imprinting?

Accepted Answer

It is the process by which genes are silenced based on which parent they are inherited from.

Question 15

Which of the following statements about mitochondrial inheritance is correct?

Accepted Answer

Mitochondrial genes are inherited only from the mother.

Question 16

A male with Klinefelter syndrome has which of the following sex chromosome compositions?

Accepted Answer

XXY

Question 17

If a crossover occurs between two linked genes during meiosis, what is the result in the gametes produced?

Accepted Answer

Some gametes will have recombinant combinations of alleles.

Question 18

Which of the following best explains why genes that are far apart on the same chromosome can have a recombination frequency near 50%?

Accepted Answer

Crossing over between them occurs so frequently that they assort almost independently.

Question 19

A trisomic zygote is best described as:

Accepted Answer

A zygote with three copies of a particular chromosome.

Question 20

Which of the following is a real-world example of a disease caused by a mutation in mitochondrial DNA?

Accepted Answer

Leber's hereditary optic neuropathy (LHON)

CH15 - Chromosomal Basis of Inheritance and Extensions of Mendelian Genetics

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