Question 1

Which of the following best describes the difference between euchromatin and heterochromatin in a eukaryotic cell?

Accepted Answer

Euchromatin is loosely packed and contains many expressed genes, while heterochromatin is densely packed and contains few expressed genes.

Question 2

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 3

A mutation occurs in a somatic cell of a human. Which of the following is true regarding the inheritance of this mutation?

Accepted Answer

The mutation will only affect a patch of cells derived from the original mutated cell and will not be inherited by the next generation.

Question 4

Which of the following events occurs during anaphase of mitosis?

Accepted Answer

Sister chromatids separate and move toward opposite spindle poles.

Question 5

What is the primary function of cohesin during mitosis?

Accepted Answer

To hold sister chromatids together until anaphase.

Question 6

Which of the following best explains why meiosis results in genetic diversity among gametes?

Accepted Answer

Crossing over and independent assortment occur during meiosis.

Question 7

A human cell with 46 chromosomes undergoes mitosis. How many chromosomes will each daughter cell have after cytokinesis?

Accepted Answer

$$46$$

Question 8

Which of the following is a hallmark event of prophase I in meiosis but NOT in mitosis?

Accepted Answer

Pairing of homologous chromosomes (synapsis)

Question 9

In Drosophila melanogaster, a white-eyed male is crossed with a red-eyed female. All F1 offspring have red eyes. What does this indicate about the white-eye allele?

Accepted Answer

It is recessive and X-linked.

Question 10

Which of the following best describes dosage compensation in placental mammals?

Accepted Answer

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

Question 11

A male patient is found to have an X-linked recessive disorder. Which of the following is the most likely genotype for this individual?

Accepted Answer

$$X^rY$$

Question 12

Which of the following is true regarding the outcome of meiosis II?

Accepted Answer

Sister chromatids are separated, resulting in haploid cells.

Question 13

Which of the following is a real-world example of an X-linked recessive disorder?

Accepted Answer

Hemophilia A

Question 14

In mammals, what is the role of the SRY gene?

Accepted Answer

It triggers the development of male phenotypic characteristics.

Question 15

Which of the following best explains why X-linked recessive traits are more commonly expressed in males than in females?

Accepted Answer

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

Question 16

A geneticist observes a 1:1 ratio of red-eyed to white-eyed offspring in both male and female Drosophila from a particular cross. Which cross most likely produced this result?

Accepted Answer

White-eyed female × red-eyed male

Question 17

Which of the following is a direct consequence of nondisjunction during meiosis?

Accepted Answer

Some gametes may have an abnormal number of chromosomes, leading to disorders such as Turner syndrome.

Question 18

Which of the following statements about the Z/W sex determination system is correct?

Accepted Answer

Females are heterogametic (ZW) and males are homogametic (ZZ).

Question 19

Which of the following best describes the outcome of mitosis in a diploid organism?

Accepted Answer

Two diploid cells are produced, each genetically identical to the parent cell.

Cell Division and Chromosome Heredity: Structured Study Notes

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