Question 1

Which of the following statements best explains why binary fission in bacteria can lead to rapid population growth?

Accepted Answer

Binary fission produces genetically identical clones, and each round of division doubles the population, resulting in exponential growth described by $$	ext{Number of cells} = 2^n.$$

Question 2

During which phase of the eukaryotic cell cycle does DNA replication occur, and what is the result regarding chromosome structure?

Accepted Answer

DNA replication occurs during S phase, resulting in each chromosome consisting of two sister chromatids held together by cohesin proteins.

Question 3

A researcher observes a eukaryotic cell with condensed chromosomes, a forming mitotic spindle, and centrosomes beginning to separate. Which stage of mitosis is this cell most likely in?

Accepted Answer

Prophase

Question 4

Which of the following correctly distinguishes between a centromere and a kinetochore?

Accepted Answer

The centromere is a narrow region of the chromosome where kinetochores form, while the kinetochore is a protein complex that binds spindle microtubules at the centromere.

Question 5

If a human somatic cell has 46 chromosomes before S phase, how many chromosomes and how much DNA (relative to before S phase) will it have after S phase but before mitosis is complete?

Accepted Answer

46 chromosomes and 2X the DNA

Question 6

Which of the following events marks the beginning of prometaphase in mitosis?

Accepted Answer

Breakdown of the nuclear membrane, releasing chromosomes into the cytoplasm

Question 7

A mutation prevents the formation of cohesin proteins in a eukaryotic cell. Which of the following would most likely be observed during mitosis?

Accepted Answer

Sister chromatids would not be held together after S phase, leading to errors in chromosome segregation during mitosis.

Question 8

Which of the following best describes the role of condensin proteins during mitosis?

Accepted Answer

Condensin proteins promote chromosome condensation during prophase.

Question 9

During metaphase of mitosis, which of the following is true regarding the attachment of chromosomes?

Accepted Answer

Each sister chromatid's kinetochore is attached to microtubules from opposite spindle poles, aligning chromosomes at the metaphase plate.

Question 10

Which of the following best explains why cytokinesis differs between animal and plant cells?

Accepted Answer

Animal cells use a contractile ring of actin-myosin to pinch the cell in two, while plant cells form a cell plate that develops into a new cell wall.

Question 11

A scientist observes a cell in which the chromosomes are de-condensing, the nuclear membrane is reforming, and cytokinesis is beginning. Which stage of mitosis is this cell in?

Accepted Answer

Telophase

Question 12

Which of the following is NOT a function of mitosis in multicellular eukaryotes?

Accepted Answer

Production of gametes for sexual reproduction

Question 13

If a bacterial population starts with 1 cell and undergoes 10 rounds of binary fission, how many cells will be present at the end? Use the formula $$	ext{Number of cells} = 2^n.$$

Accepted Answer

$$2^{10} = 1024$ cells

Question 14

Which of the following best describes the role of the mitotic spindle during mitosis?

Accepted Answer

It attaches to kinetochores and helps segregate sister chromatids to opposite poles of the cell.

Question 15

A cell is observed with chromosomes aligned at the metaphase plate, each attached to spindle fibers from opposite poles. What would happen if the spindle checkpoint failed at this stage?

Accepted Answer

Sister chromatids might not separate properly, leading to aneuploid daughter cells.

Question 16

Which of the following correctly matches a mitotic phase with its main event?

Accepted Answer

Anaphase: Sister chromatids separate and move to opposite poles.

Question 17

Which of the following structures is responsible for attaching spindle microtubules to chromosomes during mitosis?

Accepted Answer

Kinetochore

Question 18

A plant cell is observed forming a new structure at its equator during cytokinesis. What is this structure, and what is its function?

Accepted Answer

Cell plate; forms a new cell wall separating the two daughter cells

Question 19

Which of the following best describes the relationship between chromosome number and DNA content after S phase in a human cell?

Accepted Answer

Chromosome number remains the same, but DNA content doubles.

Cell Division and the Cell Cycle: Binary Fission, Mitosis, and Cytokinesis

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