Question 1

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 2

A woman who is a carrier for an X-linked recessive disorder (genotype $$X^N X^n) $$and a man with normal alleles ($$X^N Y) $$have children. What is the probability that their son will be affected by the disorder?

Accepted Answer

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

Question 3

If two people with normal color vision (N) have a color-blind son (n), what are the genotypes of the parents?

Accepted Answer

$$X^N X^n$$ and $$X^N Y$$

Question 4

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

Accepted Answer

One X chromosome is randomly inactivated in each cell, leading to mosaic expression.

Question 5

The mosaic black and orange coloration in calico cats is a result of:

Accepted Answer

Random X-chromosome inactivation in heterozygous females

Question 6

Which gene is responsible for X-chromosome inactivation and what is its mechanism?

Accepted Answer

The Xist gene, which produces RNA that coats and inactivates the X chromosome

Question 7

A man with an X-linked recessive disorder and a woman with two normal alleles have children. Which of the following is true?

Accepted Answer

All daughters will be carriers.

Question 8

In Morgan's experiment with fruit flies, what did the observation of nonparental phenotypes in the offspring indicate?

Accepted Answer

Genes on the same chromosome can be separated by crossing over.

Question 9

If the recombination frequency between two genes is $$17\%$$, what does this suggest about their physical distance on the chromosome?

Accepted Answer

They are moderately far apart.

Question 10

Which of the following best describes the structure of a nucleosome?

Accepted Answer

A nucleosome consists of DNA wrapped around a core of eight histone proteins.

Question 11

Which chemical property allows histones to interact with DNA?

Accepted Answer

Histones are positively charged, and DNA is negatively charged.

Question 12

What is the significance of Frederick Griffith's experiment with Streptococcus pneumoniae?

Accepted Answer

It showed that information specifying virulence could be transferred between cells, a process called transformation.

Question 13

In the Hershey-Chase experiment, what was the key evidence that DNA is the genetic material?

Accepted Answer

Radioactive DNA was found inside infected bacteria.

Question 14

Which of the following statements about chromatin packaging is correct?

Accepted Answer

Chromatin packaging is dynamic and can be modified for cell processes.

Question 15

Which type of chromatin is more accessible to transcription machinery?

Accepted Answer

Euchromatin

Question 16

A genetic map is constructed using recombination data. What does a higher recombination frequency between two genes indicate?

Accepted Answer

The genes are farther apart on the chromosome.

Question 17

Which of the following is true about Y-linked genes?

Accepted Answer

Y-linked genes are few and only found in males.

Question 18

Which equation correctly calculates recombination frequency?

Accepted Answer

$$	ext{Recombination frequency} = \frac{	ext{Number of recombinant offspring}}{	ext{Total number of offspring}} 	imes 100$$

Question 19

Which process is responsible for breaking the physical connection between genes on the same chromosome, resulting in genetic recombination?

Accepted Answer

Homologous crossing over

X-Linked and Y-Linked Inheritance, Chromosome Structure, and Genetic Mapping

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