Mitosis vs Meiosis Worksheet Answer Key | Exercises Cell Biology ... - Free Printable

The image you've uploaded is a completed worksheet titled "Mitosis and Meiosis Practice", with handwritten answers. Below, I'll go through each question, explain the correct answers, and clarify any potential misunderstandings or areas for improvement.

---

1. Complete the concept map comparing mitosis and meiosis

This concept map compares mitosis and meiosis using key terms.

#### Mitosis Side:
- 1. Body cell – Mitosis occurs in somatic (body) cells.
- 2. Diploid – Body cells are diploid (2n).
- 3. One cell division – Mitosis involves one round of cell division.
- 4. Two diploid cells – Result: two genetically identical diploid daughter cells.
- 5. Same – The number of chromosomes remains the same.
- 6. Chromosomes – Refers to chromosome number.
- 7. Parent cell – The original cell that divides.

✔ This side is correct.

#### Meiosis Side:
- 8. Gamete-producing cell – Meiosis occurs in reproductive cells (germ cells).
- 9. Two cell divisions – Meiosis includes Meiosis I and II.
- 10. Four haploid cells – Result: four genetically diverse haploid gametes.
- 11. Half – The number of chromosomes is halved.
- 12. Chromosomes – Refers to chromosome number.
- 13. Parent cell – Original cell before division.

✔ This side is also correct.

> ✔ All answers in the concept map are accurate.

---

2. Define homologous chromosome.

Answer: *Pairs of the same chromosome.*

Explanation:
Homologous chromosomes are pairs of chromosomes (one from each parent) that have the same genes at the same loci but may have different alleles. They are similar in size, shape, and genetic content. For example, in humans, chromosome 1 from mom and chromosome 1 from dad are homologous.

✔ Correct answer — though it could be slightly expanded:
> "Homologous chromosomes are a pair of chromosomes (one maternal and one paternal) that carry genes for the same traits in the same order."

---

3. Describe 2 parts of meiosis that are similar to mitosis.

a.) Division of chromosomes
b.) Start with diploid cells

These are both correct.

Other valid answers could include:
- Both involve DNA replication before division.
- In both, chromosomes line up at the equator during metaphase.
- Sister chromatids separate during anaphase (in mitosis and meiosis II).

✔ Answers are acceptable, though part (b) might be better phrased as “both start with a diploid parent cell.”

---

4. Identify whether each process occurs during mitosis, meiosis, or both.

Let’s evaluate each:

| Process | Answer Given | Correct? | Explanation |
|--------|--------------|---------|-----------|
| a. Sister chromatids separate | Meiosis | ✘ Incorrect | Actually occurs in both mitosis and meiosis II. So correct answer is both. |
| b. Haploid cells are formed | Meiosis | ✔ Correct | Only meiosis produces haploid gametes. |
| c. Cell division occurs once | Mitosis | ✔ Correct | Mitosis has one division; meiosis has two. |
| d. Homologous chromosomes pair | Meiosis | ✔ Correct | Pairing (synapsis) happens only in prophase I of meiosis. |
| e. 4 haploid cells are the final result | Meiosis | ✔ Correct | Meiosis produces 4 haploid cells; mitosis produces 2 diploid cells. |
| f. Crossing over occurs | Meiosis | ✔ Correct | Occurs in prophase I of meiosis. |
| g. Cell division occurs twice | Meiosis | ✔ Correct | Meiosis I and II. |
| h. Replicated chromosomes line up in the middle of the cell | Both | ✔ Correct | Metaphase of both mitosis and meiosis (though alignment differs). |
| i. 2 diploid cells are the final result | Mitosis | ✔ Correct | Mitosis produces two diploid daughter cells. |

✘ Error in (a):
Sister chromatids separate → should be both, not just meiosis.

> ✔ All other answers are correct.

---

5. Does the parent cell in Mitosis start off as diploid or haploid? Are the resulting cells at the end of Mitosis diploid or haploid?

Answer: Diploid / Diploid

✔ Correct.
Mitosis starts with a diploid (2n) parent cell and produces two diploid daughter cells.

---

6. Does the parent cell in Meiosis start off as diploid or haploid? Are the resulting cells at the end of Meiosis diploid or haploid?

Answer: Diploid / Haploid

✔ Correct.
Meiosis begins with a diploid germ cell and ends with four haploid gametes.

---

7. How does the number of chromosomes in a sex cell compare with the number of chromosomes in the parent cell?

Answer: Half

✔ Correct.
Sex cells (gametes) are haploid, so they have half the number of chromosomes compared to the diploid parent cell.

Example: Humans have 46 chromosomes in body cells (diploid), and 23 in gametes (haploid).

---

8. The picture is showing a pair of ______ chromosomes.

Answer: Homologous

✔ Correct.
The image shows two X-shaped chromosomes that are similar in size and shape — this represents a homologous pair (one from each parent).

Note: If it were sister chromatids, they'd be joined at the centromere and part of the same chromosome. Here, they are two separate chromosomes — hence, homologous.

---

✔ Final Assessment:

Most answers are correct. The only error is:

> Question 4a: "Sister chromatids separate" → Should be "both", not just "meiosis".

Because:
- In mitosis: sister chromatids separate during anaphase.
- In meiosis II: sister chromatids also separate (analogous to mitosis).

So the correct answer is both.

---

🔧 Suggested Correction:

Change #4a from "meiosis" to "both".

---

📝 Summary of Key Concepts:

| Feature | Mitosis | Meiosis |
|--------|--------|--------|
| Cell type | Body cells | Gamete-producing cells |
| Starting cell | Diploid | Diploid |
| Divisions | One | Two |
| Daughter cells | 2 diploid | 4 haploid |
| Genetic identity | Identical | Genetically diverse |
| Homologous pairing | No | Yes (Prophase I) |
| Crossing over | No | Yes |
| Sister chromatid separation | Anaphase | Anaphase II |

---

✔ Overall, the student did very well! Just one small correction needed. Great job understanding the differences between mitosis and meiosis.