Assertion : Fluidity of plasma membrane is due to presence of phospholipids.
Reason: Fatty acids of the phospholipids have kinks which do not allow the packing of molecules.

Options

A. If both Assertion and Reason are true and Reason is correct explanation of Assertion.
B. If both Assertion and Reason are true and Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If both Assertion and Reason are false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided:

**Assertion:** Fluidity of plasma membrane is due to the presence of phospholipids.
**Reason:** Fatty acids of the phospholipids have kinks which do not allow the packing of molecules.

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that the fluidity of the plasma membrane is due to phospholipids.
- Phospholipids are a major component of the plasma membrane, and their structure contributes significantly to the membrane's fluidity.

**Hint:** Consider the role of phospholipids in the structure of the membrane.

2. **Analyzing the Reason:**
- The reason given is that the fatty acids of phospholipids have kinks which prevent tight packing of the molecules.
- Unsaturated fatty acids contain one or more double bonds, which introduce kinks in their structure. These kinks prevent the fatty acids from packing closely together, thus enhancing the fluidity of the membrane.

**Hint:** Think about how the structure of fatty acids affects their interactions with each other.

3. **Connecting Assertion and Reason:**
- The assertion is true because phospholipids are essential for maintaining membrane fluidity.
- The reason is also true as the kinks in the unsaturated fatty acids indeed prevent tight packing, which contributes to the fluidity mentioned in the assertion.
- Therefore, the reason correctly explains the assertion.

**Hint:** Reflect on how the properties of molecules can explain larger biological phenomena.

4. **Evaluating the Options:**
- Option 1: Both assertion and reason are true, and the reason is the correct explanation of the assertion. (This is correct)
- Option 2: Both assertion and reason are true, but the reason is not the correct explanation of the assertion. (This is incorrect)
- Option 3: Assertion is true, but reason is false. (This is incorrect)
- Option 4: Both assertion and reason are false. (This is incorrect)

### Conclusion:
The correct answer is **Option 1**: Both assertion and reason are true, and the reason is the correct explanation of the assertion.