Arrange the following events of meiosis in correct sequence
(i) Crossing over
(ii) Synapsis
(iii) Terminalisation of chiasmata
(iv) Disappearance of nucleolus.

Options

A. (ii), (i), (iv), (iii)
B. (ii), (i), (iii), (iv)
C. (i), (ii), (iii), (iv)
D. (ii), (iii), (iv), (i)

Answer

To arrange the events of meiosis in the correct sequence, we need to understand the process of meiosis and the specific events listed in the question. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Identify the events**: The events given are:
- (i) Crossing over
- (ii) Synapsis
- (iii) Terminalisation of chiasmata
- (iv) Disappearance of nucleolus

2. **Understanding Synapsis**:
- Synapsis is the process where homologous chromosomes pair up during prophase I of meiosis. This is the first step that occurs in the meiosis process.

3. **Understanding Crossing Over**:
- After synapsis, crossing over occurs. This is the exchange of genetic material between homologous chromosomes, which increases genetic diversity. This happens during prophase I as well.

4. **Understanding Terminalisation of Chiasmata**:
- After crossing over, the chiasmata (the points where crossing over occurs) move towards the ends of the chromosomes, which is known as terminalisation of chiasmata. This is a crucial step that prepares the chromosomes for separation.

5. **Understanding Disappearance of Nucleolus**:
- The disappearance of the nucleolus occurs during prophase I as well, but it typically happens after the chromosomes have condensed and are becoming visible.

6. **Arranging the Events**:
- Based on the understanding of the events:
- (ii) Synapsis (1st)
- (i) Crossing over (2nd)
- (iii) Terminalisation of chiasmata (3rd)
- (iv) Disappearance of nucleolus (4th)

### Final Sequence:
The correct sequence of events in meiosis is:
1. Synapsis (ii)
2. Crossing over (i)
3. Terminalisation of chiasmata (iii)
4. Disappearance of nucleolus (iv)