Question 1

Which of the following statements best describes the chromosome theory of inheritance?

Accepted Answer

Genes are located on chromosomes, and the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 2

Why are fruit flies (Drosophila melanogaster) particularly useful for genetic studies?

Accepted Answer

They have only four pairs of chromosomes, breed quickly, and produce many offspring.

Question 3

In Morgan's experiment with fruit flies, why did only male F2 offspring have white eyes?

Accepted Answer

The gene for eye color is located on the X chromosome, and males have only one X chromosome.

Question 4

A Barr body is formed as a result of which process in female mammals?

Accepted Answer

Random inactivation of one X chromosome in each cell during embryonic development.

Question 5

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

Accepted Answer

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

Question 6

If two genes are located far apart on the same chromosome, what is the expected recombination frequency between them?

Accepted Answer

$$50\%$$

Question 7

A genetic map shows the order of genes along a chromosome. If gene A and gene B have a recombination frequency of $$12\%$$, what does this indicate about their physical relationship?

Accepted Answer

They are relatively close together on the same chromosome.

Question 8

Which chromosomal alteration is correctly matched with its description?

Accepted Answer

Duplication: repeats a segment of a chromosome.

Question 9

A child is born with cri du chat syndrome, which is caused by a specific chromosomal abnormality. What is the nature of this abnormality?

Accepted Answer

A deletion on chromosome 5.

Question 10

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

Accepted Answer

It is inherited exclusively from the mother.

Question 11

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

Accepted Answer

All of her children will inherit the disorder.

Question 12

Which of the following is an example of aneuploidy?

Accepted Answer

A human zygote with three copies of chromosome 21.

Question 13

Turner syndrome (XO) in humans is caused by which chromosomal event?

Accepted Answer

Nondisjunction of sex chromosomes during meiosis.

Question 14

Which of the following best explains the concept of genomic imprinting?

Accepted Answer

The expression of an allele depends on whether it was inherited from the mother or the father.

Question 15

A male with Klinefelter syndrome has which of the following karyotypes?

Accepted Answer

$$XXY$$

Question 16

If a gene is located on the Y chromosome, which of the following statements is true about its inheritance?

Accepted Answer

It is passed from father to all sons.

Question 17

A cross between a female carrier of an X-linked recessive disorder and a normal male will result in what proportion of affected sons?

Accepted Answer

$$50\%$$

Question 18

Which of the following chromosomal changes is most likely to result in a cancer such as chronic myelogenous leukemia (CML)?

Accepted Answer

A reciprocal translocation between chromosomes 9 and 22.

Question 19

If a gene pair shows a recombination frequency of $$1\%$$, what is the distance between them on a genetic map?

Accepted Answer

$$1$$ map unit

Question 20

Which of the following best describes polyploidy?

Accepted Answer

An organism has more than two complete sets of chromosomes.

Ch. 15: The Chromosomal Basis of Inheritance – Study Notes

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