Educational worksheet illustrating the cell cycle and mitosis phases with labeled diagrams and related questions.

Let's solve this step-by-step based on the diagram and questions provided. This worksheet is about the cell cycle, specifically focusing on mitosis and cytokinesis.

---

Step 1: Labeling the Diagram

First, identify each labeled part of the cell cycle stages in the diagram.

The cells are shown in a cycle:

- A: Prophase
- B: Metaphase
- C: Anaphase
- D: Telophase
- E: Interphase (specifically G2 phase or late interphase)

Now label the numbered parts:

#### Cell E (Interphase):
- 5: Nucleus
- 6: Nuclear membrane
- 7: Nucleolus
- 8: Chromatin (uncondensed chromosomes)

#### Cell A (Prophase):
- 9: Centrioles
- 10: Spindle fibers (microtubules)
- 1: Centromere
- 2: Chromosome (consisting of two sister chromatids)

#### Cell B (Metaphase):
- 3: Chromosomes lined up at equator
- 4: Cleavage furrow (in animal cells; this appears during cytokinesis)

Wait — actually, Cell D shows two daughter cells forming, so:
- 4: Cleavage furrow (in animal cells)
- 3: Chromosomes moving apart → this is Anaphase

Let’s reassign correctly:

- A: Prophase
- B: Metaphase
- C: Anaphase
- D: Telophase (with cytokinesis starting)
- E: Interphase

Now correct labels:

#### E (Interphase):
- 5: Nucleus
- 6: Nuclear membrane
- 7: Nucleolus
- 8: Chromatin

#### A (Prophase):
- 9: Centrioles
- 10: Spindle fibers
- 1: Centromere
- 2: Chromosome (sister chromatids)

#### B (Metaphase):
- 3: Chromosomes aligned at the metaphase plate

#### C (Anaphase):
- 3: Sister chromatids separating (now called chromosomes)

#### D (Telophase & Cytokinesis):
- 4: Cleavage furrow (animal cell division)
- 5: Nucleus reforming

But wait — in the diagram:
- Cell D shows two nuclei forming with cleavage furrow → Telophase + Cytokinesis
- So D = Telophase
- C = Anaphase
- B = Metaphase
- A = Prophase
- E = Interphase

Now let’s answer the questions.

---

Answer Key for Questions:

#### 11. What moves the chromatids during mitosis?
Answer: Spindle fibers (microtubules)
→ They attach to the centromeres and pull chromatids apart.

#### 12. What anchors the spindle?
Answer: Centrosomes (or centrioles)
→ Centrosomes organize the spindle fibers; they move to opposite poles.

#### 13. What are the four phases of mitosis?
Answer: Prophase, Metaphase, Anaphase, Telophase

#### 14. How many daughter cells are created from mitosis and cytokinesis?
Answer: Two
→ One parent cell divides into two genetically identical daughter cells.

#### 15. During what phase does cytokinesis begin?
Answer: Telophase
→ In animal cells, cleavage furrow starts forming during telophase.

#### 16. If a human cell has 46 chromosomes, how many chromosomes will be in each daughter cell?
Answer: 46 chromosomes
→ Mitosis produces genetically identical cells, so chromosome number remains the same.

#### 17. If a dog cell has 72 chromosomes, how many daughter cells will be created during a single cell cycle?
Answer: Two daughter cells
→ Each will have 72 chromosomes
→ Because mitosis maintains chromosome number.

#### 18. The nuclear membrane dissolves during what phase?
Answer: Prophase
→ Nuclear envelope breaks down so chromosomes can move freely.

#### 19. In the cell pictured above, how many chromosomes are present during prophase?
Look at Cell A (Prophase): There are 4 chromosomes, each consisting of two sister chromatids.
So, 4 chromosomes (even though they're duplicated).

> Note: Chromosome count is based on centromeres. Each structure with one centromere = one chromosome.

Answer: 4 chromosomes

#### 20. What structure holds the individual chromatids together?
Answer: Centromere
→ It’s the region where sister chromatids are joined.

---

Final Answers Summary:

| Question | Answer |
|--------|--------|
| 11 | Spindle fibers (microtubules) |
| 12 | Centrosomes / Centrioles |
| 13 | Prophase, Metaphase, Anaphase, Telophase |
| 14 | Two |
| 15 | Telophase |
| 16 | 46 |
| 17 | Two daughter cells; each has 72 chromosomes |
| 18 | Prophase |
| 19 | 4 chromosomes |
| 20 | Centromere |

---

Diagram Labels:

- A: Prophase
- B: Metaphase
- C: Anaphase
- D: Telophase
- E: Interphase

Numbered parts:
- 1: Centromere
- 2: Chromosome (sister chromatids)
- 3: Chromosomes aligning (metaphase) or separating (anaphase)
- 4: Cleavage furrow
- 5: Nucleus
- 6: Nuclear membrane
- 7: Nucleolus
- 8: Chromatin
- 9: Centrioles
- 10: Spindle fibers

✔ All answers are consistent with standard biology knowledge and the diagram.

Let me know if you'd like this formatted as a printable answer sheet!