Q1. How many chromosomes are in the middle cell?

Background

Topic: Chromosome Number During Cell Division

This question tests your understanding of chromosome number changes during the cell cycle, particularly during mitosis.

Key Terms:

• Chromosome: A DNA molecule with associated proteins, visible during cell division.

• Sister Chromatids: Identical copies of a chromosome connected by a centromere.

• Mitosis: The process by which a cell divides to produce two identical daughter cells.

Step-by-Step Guidance

1. Examine the diagram and identify the stage of the cell cycle for the middle cell.

2. Recall that before mitosis, chromosomes are duplicated, forming sister chromatids.

3. Count the number of chromosome structures present in the middle cell (each structure is considered one chromosome).

4. Compare this number to the original cell to see if the chromosome number has changed.

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Q2. The chromosome begins M phase looking as shown. When does it split?

Background

Topic: Mitosis Phases

This question tests your knowledge of the stages of mitosis and when sister chromatids separate.

Key Terms:

• M phase: The mitotic phase, including mitosis and cytokinesis.

• Sister Chromatids: Two identical DNA molecules joined at the centromere.

• Anaphase: The stage when sister chromatids are pulled apart.

Step-by-Step Guidance

1. Identify the structure shown: two sister chromatids joined at the centromere.

2. Recall the sequence of mitosis: prophase, prometaphase, metaphase, anaphase, telophase.

3. Determine at which stage the centromere splits and chromatids move apart.

4. Review the function of each mitotic phase to pinpoint when separation occurs.

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Q3. A new cell is found and separation of its chromosomes is examined. If the darker patches in the yellow lines are places where the spindle was bleached with a laser, what do these images tell us?

Background

Topic: Chromosome Movement During Mitosis

This question tests your understanding of how chromosomes move during mitosis and the role of microtubules.

Key Terms:

• Spindle fibers: Microtubules that help separate chromosomes.

• Centrosome: The microtubule organizing center.

• Chromosome end: The location where microtubules attach to chromosomes.

Step-by-Step Guidance

1. Analyze the images showing spindle fibers and the location of the bleached patches.

2. Consider what happens to the bleached area as chromosomes move: does it stay at the centrosome or chromosome end?

3. Recall the mechanism of microtubule shortening during chromosome separation.

4. Determine whether microtubules shorten at the centrosome or chromosome end based on the movement of the bleached patch.

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Q4. From prophase through metaphase of mitosis, each chromosome has ____ DNA molecules, while from anaphase through telophase of mitosis, each chromosome has ____ DNA molecule(s).

Background

Topic: DNA Content During Mitosis

This question tests your understanding of how the number of DNA molecules per chromosome changes during mitosis.

Key Terms:

• Prophase/Metaphase: Stages where chromosomes are duplicated (sister chromatids).

• Anaphase/Telophase: Stages where chromatids separate and each chromosome has one DNA molecule.

Step-by-Step Guidance

1. Recall that during prophase and metaphase, chromosomes consist of two sister chromatids (two DNA molecules).

2. During anaphase, sister chromatids separate, so each chromosome now has one DNA molecule.

3. Fill in the blanks with the correct numbers based on the stages described.

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Q5. Of the events of a typical cell division listed below, which is most likely to occur third in an animal cell that is going through mitosis?

Background

Topic: Sequence of Events in Mitosis

This question tests your knowledge of the order of events during mitosis in animal cells.

Key Terms:

• Kinetochores: Protein structures on chromosomes where spindle fibers attach.

• Chromosome doubling: Occurs before mitosis begins.

• Chromatid separation: Occurs during anaphase.

Step-by-Step Guidance

1. List the sequence of events in mitosis: chromosome duplication, spindle formation, chromosome alignment, chromatid separation, nuclear envelope formation.

2. Identify which event occurs third based on the typical order.

3. Compare the options to the sequence you listed.

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Q6. Which statement comparing cancer cells and normal somatic cells would lose points on a test?

Background

Topic: Cancer Cell Characteristics

This question tests your understanding of the differences between cancer cells and normal somatic cells.

Key Terms:

• Apoptosis: Programmed cell death.

• Contact inhibition: Normal cells stop dividing when they touch other cells.

• DNA repair: Mechanisms to fix damaged DNA.

Step-by-Step Guidance

1. Review the characteristics of cancer cells: loss of apoptosis, insensitivity to contact inhibition, rapid cell cycle, increased mobility, defective DNA repair.

2. Identify which statement is incorrect based on your knowledge.

3. Compare each option to the known characteristics of cancer cells.

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Q7. If you were given a slide and told that the cells on it were performing cytokinesis, how would you tell if you had plant cells or animal cells?

Background

Topic: Cytokinesis in Plant vs Animal Cells

This question tests your ability to distinguish between plant and animal cell cytokinesis.

Key Terms:

• Cytokinesis: Division of the cytoplasm after mitosis.

• Cell plate: Structure formed during plant cell cytokinesis.

• Cleavage furrow: Structure formed during animal cell cytokinesis.

Step-by-Step Guidance

1. Recall that plant cells form a cell plate during cytokinesis, while animal cells form a cleavage furrow.

2. Examine the slide for the presence of either structure.

3. Use this observation to determine the cell type.

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Q8. Binary fission is more like animal cell division than plant cell division because...

Background

Topic: Binary Fission vs Eukaryotic Cell Division

This question tests your understanding of similarities and differences between prokaryotic (binary fission) and eukaryotic cell division.

Key Terms:

• Binary fission: Cell division in prokaryotes.

• Cytokinesis: Division of cytoplasm in eukaryotes.

• Cleavage furrow: Structure in animal cell division.

Step-by-Step Guidance

1. Recall that binary fission involves pinching the cytoplasm to divide the cell.

2. Compare this process to animal cell division, which also involves a cleavage furrow.

3. Contrast this with plant cell division, which involves a cell plate.

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