Question 1

Which phase of meiosis best explains Mendel’s law of independent assortment, and why?

Accepted Answer

Metaphase I, because homologous chromosomes align randomly at the metaphase plate, leading to independent assortment of alleles.

Question 2

T.H. Morgan’s experiments with Drosophila melanogaster provided evidence for which of the following?

Accepted Answer

Genes are located on chromosomes, and some genes are sex-linked.

Question 3

The SRY gene is critical for human sex determination. What is its primary function?

Accepted Answer

It triggers the development of male anatomical features by initiating testis formation.

Question 4

Why are X-linked recessive diseases, such as hemophilia, more common in human males than females?

Accepted Answer

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

Question 5

A woman who is a carrier for color blindness (X	extsuperscript{N}X	extsuperscript{n}) and a man with normal vision (X	extsuperscript{N}Y) have a child. What is the probability that their son will be color blind?

Accepted Answer

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

Question 6

Which of the following best explains the tortoiseshell coloration in female cats?

Accepted Answer

Random X inactivation in each cell leads to patches of cells expressing different alleles for fur color.

Question 7

Linked genes tend to be inherited together because:

Accepted Answer

They are located close to each other on the same chromosome.

Question 8

In a dihybrid cross involving two linked genes, which of the following would indicate that crossing over has occurred?

Accepted Answer

The appearance of recombinant phenotypes in the offspring.

Question 9

A geneticist observes a karyotype with 47 chromosomes, including three copies of chromosome 21. What is the name of this condition, and what type of chromosomal alteration does it represent?

Accepted Answer

Down syndrome; trisomy

Question 10

Which chromosomal alteration is responsible for chronic myelogenous leukemia (CML)?

Accepted Answer

A reciprocal translocation between chromosomes 9 and 22.

Question 11

If nondisjunction occurs during meiosis II in a human oocyte, which of the following gamete combinations is possible?

Accepted Answer

Two normal gametes, one gamete with an extra chromosome, and one gamete missing a chromosome.

Question 12

Which of the following best distinguishes between linked genes and sex-linked genes?

Accepted Answer

Linked genes are located close together on any chromosome, while sex-linked genes are specifically located on sex chromosomes.

Question 13

Which chromosomal abnormality is characterized by a female with only one X chromosome (45, X)?

Accepted Answer

Turner syndrome

Question 14

A child is born with the karyotype 47, XXY. Which syndrome does this represent, and what is the likely cause?

Accepted Answer

Klinefelter syndrome; nondisjunction during meiosis

Question 15

Which of the following chromosomal changes would most likely result in a gene dosage effect due to the presence of extra genetic material?

Accepted Answer

Duplication

Question 16

A genetic disorder is caused by a deletion on the short arm of chromosome 5, resulting in intellectual disability and a distinctive cry in infants. What is this disorder?

Accepted Answer

Cri du chat syndrome

Question 17

Which of the following best describes polyploidy?

Accepted Answer

The presence of more than two complete sets of chromosomes in an organism.

Question 18

If a female is heterozygous for an X-linked gene, what is the expected proportion of her somatic cells expressing each allele due to X inactivation?

Accepted Answer

$$\frac{1}{2}$$ for each allele

Question 19

Which of the following scenarios would most likely result in a child with trisomy X syndrome?

Accepted Answer

A female with three X chromosomes due to nondisjunction during meiosis.

Question 20

Which of the following best explains why crossing over can unlink genes that are located on the same chromosome?

Accepted Answer

Crossing over exchanges segments between homologous chromosomes, creating new allele combinations.

The Chromosomal Basis of Inheritance: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드