Question 1

During which phase of the cell cycle does DNA replication occur, and what is the ploidy of the cell immediately after this phase?

Accepted Answer

DNA replication occurs during S phase; the cell is diploid with duplicated chromosomes.

Question 2

A researcher observes a human cell with 92 unduplicated chromosomes being pulled toward opposite poles. Which phase is this cell in?

Accepted Answer

Anaphase of mitosis

Question 3

Which of the following best describes the difference between kinetochore and nonkinetochore microtubules during mitosis?

Accepted Answer

Kinetochore microtubules attach to chromosomes at the centromere; nonkinetochore microtubules interact with each other to elongate the cell.

Question 4

A mutation causes the cohesin proteins to degrade prematurely during mitosis. What is the most likely consequence?

Accepted Answer

Sister chromatids may separate too early, leading to daughter cells with abnormal chromosome numbers.

Question 5

Which checkpoint in the cell cycle ensures that all chromosomes are properly attached to the spindle before separation, and what could happen if this checkpoint fails?

Accepted Answer

M checkpoint; cells may undergo nondisjunction, resulting in aneuploidy.

Question 6

Which process is responsible for the genetic variation observed in offspring produced by sexual reproduction?

Accepted Answer

Independent assortment, crossing over, and random fertilization during meiosis

Question 7

A cell is observed to have a cell plate forming during cytokinesis. Which type of organism and cell division is most likely occurring?

Accepted Answer

Plant cell during mitosis

Question 8

If a human somatic cell fails to pass the G1 checkpoint, what is its likely fate?

Accepted Answer

It will enter the G0 phase and stop dividing.

Question 9

Which of the following best explains why homologous chromosomes, but not sister chromatids, separate during Anaphase I of meiosis?

Accepted Answer

Cohesins remain at the centromere, keeping sister chromatids together, while homologous chromosomes are pulled apart.

Question 10

A geneticist is analyzing a karyotype and observes 47 chromosomes in a human cell. Which checkpoint likely failed, and what is the result called?

Accepted Answer

M checkpoint; aneuploidy

Question 11

Which of the following equations correctly represents the chromosome number in human somatic cells and gametes?

Accepted Answer

$$2n = 46 in $$somatic cells; $$n = 23 in $$gametes

Question 12

Which event during meiosis increases genetic diversity by exchanging DNA between homologous chromosomes?

Accepted Answer

Crossing over during Prophase I

Question 13

A scientist observes a cell with chromosomes aligned single file at the metaphase plate, each chromosome consisting of two sister chromatids. Which phase and process is this?

Accepted Answer

Metaphase of mitosis

Question 14

Which of the following best describes the difference between a duplicated and unduplicated chromosome?

Accepted Answer

A duplicated chromosome consists of two sister chromatids joined at the centromere; an unduplicated chromosome consists of a single chromatid.

Question 15

Which of the following scenarios best illustrates density-dependent inhibition?

Accepted Answer

A wound heals as cells divide until the gap is filled, then cell division stops.

Question 16

If a plant cell undergoes mitosis but not cytokinesis, what will be the result?

Accepted Answer

One cell with two nuclei

Question 17

Which of the following is true regarding the outcome of meiosis in humans?

Accepted Answer

It produces four haploid cells.

Question 18

Which of the following best explains why gametes are haploid?

Accepted Answer

They contain only one set of chromosomes, so that upon fertilization, the diploid number is restored.

Question 19

Which of the following is NOT a source of genetic variation in sexually reproducing organisms?

Accepted Answer

Binary fission

Question 20

A cell is observed to be in a nondividing state for an extended period. Which phase is it most likely in, and what is this phase called?

Accepted Answer

G0 phase; quiescent state

Cell Division: Mitosis and Meiosis (Chapters 9 & 10) Study Guide

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