Which of the following is unique to mitosis and not a part of meiosis?
(a) Homologous chromosomes behave independently
(b) Chromatids are separated during anaphase
(c) Homologous chromosomes pair and form bivalents
(d) Homologous chromosomes crossover .

Options

A. Homologous chromosomes behave independently
B. Chromatids are separated during anaphase
C. Homologous chromosomes pair and form bivalents
D. Homologous chromosomes crossover .

Answer

To solve the question, we need to identify which option is unique to mitosis and not part of meiosis. Let's analyze each option step by step.

### Step 1: Analyze Option (a) - Homologous chromosomes behave independently
- In mitosis, homologous chromosomes do not pair; they behave independently.
- In meiosis, specifically during prophase I, homologous chromosomes pair up and do not behave independently due to the formation of bivalents.
- **Conclusion**: This statement is true for mitosis but not for meiosis. However, it is not unique to mitosis.

### Step 2: Analyze Option (b) - Chromatids are separated during anaphase
- In both mitosis and meiosis II, chromatids are separated during anaphase.
- In meiosis I, homologous chromosomes are separated, but in meiosis II, it is the chromatids that separate.
- **Conclusion**: This process occurs in both mitosis and meiosis II, so it is not unique to mitosis.

### Step 3: Analyze Option (c) - Homologous chromosomes pair and form bivalents
- This process occurs only in meiosis I during prophase I.
- In mitosis, homologous chromosomes do not pair and therefore do not form bivalents.
- **Conclusion**: This statement is true for meiosis and not for mitosis, so it is not unique to mitosis.

### Step 4: Analyze Option (d) - Homologous chromosomes crossover
- Crossing over occurs during prophase I of meiosis, allowing for genetic recombination.
- This process does not occur in mitosis.
- **Conclusion**: This statement is true for meiosis and not for mitosis, so it is not unique to mitosis.

### Final Conclusion:
After analyzing all options, we find that none of the options are unique to mitosis. However, the option that best describes a characteristic of mitosis is option (a) because it highlights the independent behavior of chromosomes during mitosis, which is not the case in meiosis.

### Answer:
(a) Homologous chromosomes behave independently.