Question 1

Which structure is shown in the first image, and what is its significance during cell division?

Accepted Answer

It is a duplicated chromosome with two sister chromatids, which are separated during mitosis to ensure each daughter cell receives identical genetic material.

Question 2

Refer to the second image. What phase of mitosis is depicted, and what key event occurs during this phase?

Accepted Answer

Metaphase; chromosomes align at the metaphase plate, attached to spindle fibers from opposite poles.

Question 3

The cell cycle diagram (third and sixth images) shows several phases. During which phase does DNA replication occur, and what is the result?

Accepted Answer

S phase; the DNA content of the cell doubles.

Question 4

A cell is observed with chromosomes aligned at the center of the cell, spindle fibers attached to kinetochores, and centrosomes at opposite poles. Which phase is this, and what would happen if the spindle checkpoint failed?

Accepted Answer

Metaphase; chromosomes might not segregate properly, leading to aneuploidy.

Question 5

In the mitotic spindle experiment, fluorescently labeled microtubules were marked with a laser. As anaphase proceeded, the mark stayed near the spindle pole while the kinetochore side shortened. What does this demonstrate?

Accepted Answer

Microtubules depolymerize at the kinetochore end, moving chromosomes toward the poles.

Question 6

If a cell has 8 picograms of DNA immediately after mitosis, how much DNA would it have at the end of S phase and at the end of G2 phase?

Accepted Answer

16 picograms at S phase, 16 picograms at G2 phase.

Question 7

A drug blocks the function of actin. Which process would be most affected in animal cells?

Accepted Answer

Cleavage furrow formation during cytokinesis

Question 8

Which of the following best describes the difference between cytokinesis in plant and animal cells?

Accepted Answer

Plant cells form a cell plate from Golgi-derived vesicles, while animal cells form a cleavage furrow using actin and myosin.

Question 9

A fertilized egg undergoes five rounds of mitotic division without any cell growth. How many cells are produced?

Accepted Answer

$$2^5 = 32$ cells

Question 10

During which phase of mitosis does the nuclear envelope fragment, allowing spindle microtubules to interact with chromosomes?

Accepted Answer

Prometaphase

Question 11

What is the role of cohesin proteins during mitosis?

Accepted Answer

They hold sister chromatids together until anaphase.

Question 12

Which event marks the transition from metaphase to anaphase in mitosis?

Accepted Answer

Separation of sister chromatids by the enzyme separase

Question 13

If a mutation prevents the formation of kinetochores, what would be the most likely consequence during mitosis?

Accepted Answer

Spindle fibers could not attach to chromosomes, preventing proper segregation.

Question 14

Which of the following best explains why multicellular organisms rely on mitosis?

Accepted Answer

For growth, repair, and development from a fertilized cell.

Question 15

What would happen if nonkinetochore microtubules failed to function during mitosis?

Accepted Answer

The cell would not elongate during anaphase, possibly leading to incomplete separation of daughter cells.

Question 16

Which phase of the cell cycle is characterized by cell growth and preparation for DNA synthesis?

Accepted Answer

G1 phase

Question 17

A cell is observed with two nuclei, each with a complete set of chromosomes, but the cytoplasm has not yet divided. Which stage is this?

Accepted Answer

Telophase

Question 18

Which of the following is true regarding the G0 phase of the cell cycle?

Accepted Answer

Cells in G0 have exited the cell cycle and are not preparing to divide.

Cell Division: Mitosis, the Cell Cycle, and Chromosome Dynamics

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