Which part of leaf is sensitive to sleep and shock movements ?

Options

A. Pinnule
B. Pinna
C. Pulvinus
D. Petiole

Answer

To answer the question "Which part of the leaf is sensitive to sleep and shock movements?", we can follow these steps:

### Step 1: Understand the Question
The question is asking about a specific part of a leaf that responds to stimuli such as touch (shock movements) and changes in light (sleep movements).

### Step 2: Identify the Plant Example
The plant example given in the transcript is Mimosa pudica, commonly known as the sensitive plant. This plant is known for its rapid movement in response to touch.

### Step 3: Recognize the Relevant Leaf Structure
In the context of Mimosa pudica, the part of the leaf that is responsible for these movements is the pulvinus. The pulvinus is a specialized structure located at the base of the leaflets.

### Step 4: Explain the Mechanism
The pulvinus acts as a hinge that allows the leaflets to fold down when touched (shock movements) or at night (sleep movements). This movement is due to changes in turgor pressure within the cells of the pulvinus.

### Step 5: Conclude with the Correct Answer
Based on the information provided, the correct answer to the question is:
**Pulvinus (Option C)**.

### Summary of Steps:
1. Understand the question regarding sensitivity to movements.
2. Identify the example of Mimosa pudica as a sensitive plant.
3. Recognize that the pulvinus is the relevant leaf structure.
4. Explain how the pulvinus facilitates movement through changes in turgor pressure.
5. Conclude that the correct answer is the pulvinus.