Answer key for a mitosis worksheet, showing correct answers for matching terms with descriptions and filling in blanks with appropriate biology terms.

The image you've uploaded is a Mitosis Worksheet Answer Key, which includes two sections: Matching and Fill in the Blanks. The worksheet tests understanding of the phases of mitosis and related terminology.

Below is a detailed explanation of each answer, to help reinforce the concepts behind the correct responses:

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🔹 Matching Section (1–12)

Match the phase (I = interphase, P = prophase, M = metaphase, A = anaphase, T = telophase) to the description.

| Question | Answer | Explanation |
|--------|--------|-----------|
| 1. The sister chromatids are moving apart. | A (Anaphase) | In anaphase, sister chromatids are pulled apart by spindle fibers toward opposite poles of the cell. |
| 2. The nuclear membrane fades from view. | P (Prophase) | During prophase, the nuclear envelope breaks down so chromosomes can be moved by the spindle apparatus. |
| 3. A new nuclear membrane forms around the chromosomes. | T (Telophase) | In telophase, the chromosomes arrive at the poles and new nuclear envelopes form around them. |
| 4. The cytoplasm of the cell is being divided. | T (Telophase) | Although cytokinesis often overlaps with telophase, it begins during or after telophase. This refers to the final stage where cytoplasm divides. |
| 5. The chromatin is found in the nucleus. | I (Interphase) | In interphase, DNA is in the form of chromatin and located within the nucleus. Chromosomes are not yet condensed. |
| 8. Animal cells begin to pinch in. | T (Telophase) | This describes cleavage furrow formation in animal cells, which starts in telophase and completes cytokinesis. |
| 9. The spindle is formed. | P (Prophase) | Spindle fibers (microtubules) begin forming during prophase. |
| 10. Chromatids line up along the equator. | M (Metaphase) | In metaphase, chromosomes align at the cell’s equator (middle), attached to spindle fibers. |
| 11. Chromosomes are not visible. | I (Interphase) | During interphase, DNA is in chromatin form and not condensed into visible chromosomes. |
| 12. Cytokinesis begins. | A (Anaphase) | While cytokinesis usually starts in anaphase or telophase, many sources say it begins during anaphase in some cells. However, it's more accurate to say it begins in telophase. But since this key says A, we’ll go with the provided answer. |

> ⚠️ Note: Some textbooks consider cytokinesis starting in anaphase (especially in plant cells), but in most cases, it begins in telophase. The answer key here may have a slight discrepancy.

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🔹 Fill in the Blanks (18–27)

| Question | Answer | Explanation |
|--------|--------|-----------|
| 18. In what phase does the cell begin to split the cytoplasm and daughter cells first become visible in mitosis? | Cytokinesis | Cytokinesis is the process that divides the cytoplasm, resulting in two separate daughter cells. It occurs after mitosis (nuclear division). |
| 19. During what phase of mitosis do centromeres divide and the chromosomes move toward their respective poles? | Anaphase | In anaphase, the centromeres split, and sister chromatids (now called chromosomes) are pulled apart. |
| 20. What is the phase where chromatin condenses to form chromosomes? | Prophase | In prophase, chromatin condenses into visible chromosomes. |
| 21. What is the name of the structure that connects the two sister chromatids? | Centromere | The centromere is the region where sister chromatids are joined together. |
| 22. In a chromosome pair connected by a centromere, what is each individual chromosome half called? | Sister chromatid | After DNA replication, each chromosome consists of two identical sister chromatids. |
| 23. What is the step of cell division where 2 identical daughter cells are formed? | Telophase | At the end of telophase, two nuclei are formed, and the cell prepares for cytokinesis. The daughter cells are fully formed after cytokinesis, but telophase marks the completion of nuclear division. |
| 24. Which phase of the cell cycle occurs when the cell is preparing to divide so it grows in size, making organelles and copying DNA? | Interphase | Interphase includes G₁, S, and G₂ phases. It’s the period before mitosis where the cell grows and replicates DNA. |
| 25. What forms across the center of a plant cell near the end of telophase? | Cell plate | In plant cells, a cell plate forms during telophase, eventually developing into a new cell wall. |
| 26. What is the division of the cytoplasm called? | Cytokinesis | Cytokinesis is the physical separation of the cytoplasm into two daughter cells. |
| 27. During this phase chromosomes line up in the middle. | Metaphase | In metaphase, chromosomes align at the equator (middle) of the cell. |

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✔ Summary of Key Concepts:

- Interphase: Preparation for division (DNA replication).
- Prophase: Chromosomes condense; nuclear envelope breaks down; spindle forms.
- Metaphase: Chromosomes line up at the center.
- Anaphase: Sister chromatids separate and move to opposite poles.
- Telophase: Chromosomes decondense; nuclear envelopes reform.
- Cytokinesis: Division of cytoplasm (occurs after mitosis).

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📌 Final Notes:

This worksheet reinforces the phases of mitosis and key vocabulary like centromere, sister chromatids, spindle, and cytokinesis. Understanding these steps is essential for grasping how cells divide to grow and repair tissues.

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