Question 1

Which of the following best explains why males are more likely to express X-linked recessive disorders than females?

Accepted Answer

Males are hemizygous for the X chromosome, so a single recessive allele will be expressed.

Question 2

A female carrier for hemophilia (an X-linked recessive disorder) has children with a normal male. What is the probability that their son will have hemophilia?

Accepted Answer

50%

Question 3

Which chromosomal alteration is most likely to result in a segment of a chromosome being lost, potentially causing severe genetic disorders?

Accepted Answer

Deletion

Question 4

In the haplo-diploid system of sex determination, such as in honeybees, what determines whether an individual is male or female?

Accepted Answer

Number of chromosome sets: females are diploid (2n), males are haploid (n)

Question 5

A calico cat displays both black and orange patches of fur. Which genetic mechanism explains this phenomenon?

Accepted Answer

X-chromosome inactivation

Question 6

Which of the following statements about linked genes is correct?

Accepted Answer

Linked genes are located close together on the same chromosome and tend to be inherited together, but crossing over can separate them.

Question 7

A genetic map is constructed using recombination frequencies. If two genes have a recombination frequency of 20%, what is their distance apart in map units?

Accepted Answer

$$20\ 	ext{map units}$$

Question 8

Which chromosomal abnormality is associated with Down syndrome?

Accepted Answer

Trisomy 21

Question 9

A male fruit fly inherits a white-eye mutation on his X chromosome. What will his eye color be?

Accepted Answer

White

Question 10

Which of the following best describes genomic imprinting?

Accepted Answer

The expression of a gene depends on which parent it was inherited from, often due to DNA methylation.

Question 11

Which syndrome is characterized by a male with an extra X chromosome (XXY), often resulting in sterility and some female secondary sexual characteristics?

Accepted Answer

Klinefelter syndrome

Question 12

Which of the following is an example of extranuclear inheritance?

Accepted Answer

Mitochondrial diseases passed from mother to all children

Question 13

If genes A and Y have a recombination frequency of 45%, and genes Z and B have a recombination frequency of 5%, which genes are most likely to be located at opposite ends of the chromosome?

Accepted Answer

A and Y

Question 14

Which chromosomal alteration is most likely to result in a segment of a chromosome being moved to another chromosome, potentially causing cancer?

Accepted Answer

Translocation

Question 15

Which sex determination system is used by birds, where females are heterogametic (ZW) and males are homogametic (ZZ)?

Accepted Answer

ZW system

Question 16

A female carrier for color blindness (X-linked recessive) has children with a normal-sighted male. What is the probability that their daughter will be color blind?

Accepted Answer

0%

Question 17

Which of the following best describes the physical basis for Mendel's law of independent assortment?

Accepted Answer

The movement of chromosomes during meiosis allows alleles to assort independently.

Question 18

Which of the following is true about Barr bodies?

Accepted Answer

They are condensed, inactive X chromosomes found in female cells.

Question 19

Which chromosomal abnormality is characterized by a female missing one X chromosome (XO), resulting in sterility and short stature?

Accepted Answer

Turner syndrome

Question 20

Which of the following best explains why a normal calico cat is almost always female?

Accepted Answer

Calico coloration is caused by random inactivation of one X chromosome, which only occurs in females.

Chromosomal Basis of Inheritance: Key Concepts and Applications

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