Question 1

Which of the following best describes the main function of the plasma membrane in both prokaryotic and eukaryotic cells?

Accepted Answer

It delimits the cell from the external environment and regulates the movement of substances in and out.

Question 2

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

Accepted Answer

DNA replication occurs during S phase; the cell is still diploid ($$2n) $$but each chromosome consists of two sister chromatids.

Question 3

Which of the following structures is responsible for organizing spindle fibers during mitosis and meiosis in animal cells?

Accepted Answer

Centrioles

Question 4

A mutation in the gene encoding separase would most likely disrupt which stage of mitosis?

Accepted Answer

Anaphase, preventing the separation of sister chromatids

Question 5

Which of the following events during meiosis is primarily responsible for increasing genetic variation in sexually reproducing species?

Accepted Answer

Crossing over between nonsister chromatids during prophase I

Question 6

In a human cell, how many chromosomes are present at metaphase of mitosis, and how are they arranged?

Accepted Answer

46 chromosomes, each consisting of two sister chromatids, aligned at the metaphase plate

Question 7

Which of the following best explains why only one functional ovum is produced from oogenesis, while spermatogenesis produces four functional sperm?

Accepted Answer

Oogenesis involves unequal cytoplasmic division, resulting in one ovum and polar bodies.

Question 8

A cell is observed to have chromosomes aligned at the metaphase plate, with spindle fibers attached to kinetochores. Which phase is this cell in, and what is the significance of this arrangement?

Accepted Answer

Metaphase; this ensures that each daughter cell will receive an identical set of chromosomes.

Question 9

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry genes for the same inherited characteristics, but may have different alleles.

Question 10

If nondisjunction occurs during Anaphase I of meiosis, what is the most likely outcome for the resulting gametes?

Accepted Answer

Some gametes will have an extra chromosome (n+1), and some will be missing a chromosome (n-1).

Question 11

Which checkpoint in the cell cycle ensures that DNA has been accurately replicated before the cell enters mitosis?

Accepted Answer

G2 checkpoint

Question 12

Which of the following best describes the difference between a bivalent and a tetrad during meiosis?

Accepted Answer

A bivalent consists of two homologous chromosomes, while a tetrad consists of four chromatids (two homologous chromosomes, each with two sister chromatids).

Question 13

Which organelle is the primary site of ATP production in eukaryotic cells?

Accepted Answer

Mitochondrion

Question 14

A cell is observed under an electron microscope and is found to lack a membrane-bound nucleus but contains a nucleoid region. Which type of cell is this most likely to be?

Accepted Answer

Prokaryotic cell

Question 15

Which of the following is a direct result of crossing over during prophase I of meiosis?

Accepted Answer

Exchange of genetic material between nonsister chromatids, increasing genetic diversity

Question 16

Which protein complex is responsible for holding sister chromatids together until anaphase?

Accepted Answer

Cohesin

Question 17

In which substage of prophase I does synapsis begin, and homologous chromosomes start pairing?

Accepted Answer

Zygonema

Question 18

Which of the following best explains why chromosomes are only visible during mitosis and meiosis?

Accepted Answer

Chromatin fibers coil and condense to form visible chromosomes during cell division.

Question 19

A researcher observes a cell with a haploid number of chromosomes, each consisting of a single chromatid, after two rounds of division. Which process has this cell most likely undergone?

Accepted Answer

Meiosis II

Question 20

Which of the following statements about the cell cycle is correct?

Accepted Answer

The S phase is when DNA synthesis occurs.

Study Guide: Mitosis and Meiosis (Genetics Chapter 2)

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