Which of the following not ocurs in Anaphase-1 but occurs in Anaphase-II :-

Options

A. Condensation of chromosomes
B. Poleward movement of chromosome
C. Contraction of spindle fibers
D. Splitting of centromere

Answer

To solve the question "Which of the following does not occur in Anaphase I but occurs in Anaphase II?" we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Anaphase I and Anaphase II**:
- Anaphase I is part of meiosis where homologous chromosomes are separated and pulled to opposite poles.
- Anaphase II is part of meiosis where sister chromatids are separated.

2. **Analyzing the Options**:
- **Option 1: Condensation of chromosomes**:
- Condensation of chromosomes occurs during prophase I and prophase II, not during anaphase. Therefore, this option does not apply to either anaphase.

- **Option 2: Poleward movement of chromosomes**:
- Poleward movement of chromosomes occurs in both Anaphase I and Anaphase II as the chromosomes are being pulled towards the poles. This option is not correct as it occurs in both phases.

- **Option 3: Contraction of spindle fibers**:
- The contraction of spindle fibers occurs during the movement of chromosomes in both mitosis and meiosis. This is more associated with the metaphase and anaphase stages, but it does not differentiate between Anaphase I and Anaphase II. Therefore, this option is also not correct.

- **Option 4: Splitting of centromere**:
- The splitting of the centromere occurs during Anaphase II when sister chromatids are separated. In Anaphase I, the homologous chromosomes are separated, but the centromeres do not split. Therefore, this option is correct as it specifically occurs in Anaphase II and not in Anaphase I.

3. **Conclusion**:
- The correct answer is **Option 4: Splitting of centromere**, as it does not occur in Anaphase I but does occur in Anaphase II.

### Final Answer:
**Option 4: Splitting of centromere**