Question 1

Which of the following best describes the main difference between mitosis and meiosis in terms of chromosome number in the resulting cells?

Accepted Answer

Mitosis produces cells with the same chromosome number as the parent cell, while meiosis produces cells with half the chromosome number.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the result in terms of chromatids?

Accepted Answer

DNA replication occurs during S phase, resulting in two sister chromatids held together by a centromere.

Question 3

Which checkpoint in the eukaryotic cell cycle is most critical for preventing the replication of damaged DNA, and what can result if this checkpoint fails?

Accepted Answer

The G1 checkpoint; failure can result in uncontrolled cell growth such as cancer.

Question 4

In the context of mitosis, what is the role of spindle fibers, and to which structure do they attach on the chromosome?

Accepted Answer

Spindle fibers attach to the kinetochores at the centromeres and separate sister chromatids.

Question 5

Which of the following events is unique to Prophase I of meiosis and contributes to genetic variation?

Accepted Answer

Crossing over between homologous chromosomes

Question 6

A human somatic cell contains 46 chromosomes. After S phase but before mitosis, how many DNA molecules and centromeres are present?

Accepted Answer

92 DNA molecules and 46 centromeres

Question 7

Which process is responsible for the formation of gametes in animals, and what is the chromosome number in these cells compared to somatic cells?

Accepted Answer

Meiosis; gametes have half the chromosome number of somatic cells.

Question 8

Which of the following best explains why sexual reproduction is advantageous in changing environments?

Accepted Answer

It increases genetic variation through mechanisms such as crossing over and independent assortment.

Question 9

In plant cells, how does cytokinesis differ from that in animal cells?

Accepted Answer

Plant cells build a new cell wall between daughter cells, while animal cells use microfilaments to pinch the cytoplasm.

Question 10

Which equation correctly represents the reduction in chromosome number during meiosis?

Accepted Answer

$$2n \rightarrow n$$

Question 11

A mutation causes the M checkpoint to fail during mitosis. What is the most likely consequence for the daughter cells?

Accepted Answer

They will have an abnormal number of chromosomes due to improper attachment of spindle fibers.

Question 12

Which of the following is true about homologous chromosomes?

Accepted Answer

They carry the same genes in the same order but may have different alleles.

Question 13

Which phase of mitosis is characterized by the alignment of chromosomes along the metaphase plate?

Accepted Answer

Metaphase

Question 14

If a cell with 24 chromosomes undergoes meiosis, how many chromosomes will each resulting gamete contain?

Accepted Answer

12

Question 15

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

It is a form of asexual reproduction where the cell divides into two genetically identical cells.

Question 16

Which of the following mechanisms does NOT contribute to genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 17

During which stage of meiosis do homologous chromosomes separate?

Accepted Answer

Anaphase I

Question 18

What is the primary function of cyclins and kinases in the cell cycle?

Accepted Answer

They regulate the progression of the cell cycle by activating or deactivating other proteins.

Question 19

Which of the following best explains why oogenesis results in one large egg and smaller polar bodies?

Accepted Answer

Unequal cytokinesis ensures that the egg retains most of the cytoplasm for early embryonic development.

Question 20

Which of the following is a correct sequence of events during mitosis?

Accepted Answer

Prophase → Metaphase → Anaphase → Telophase

Cell Cycle, Mitosis, and Meiosis: Structure, Function, and Regulation

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