Assertion : Lecithin is important in membranes .
Reason : It has amphipathic nature .

Options

A. (a) If both assertion and Reason are true and the Reason is the correct explanation of the assertion .
B. (b) If both Assertion and Reason ate true , but the reason is not the correct explanation of the assertion .
C. (c) If Assertion is true , but Reason is false
D. (d) if both Assertion and Reason are false.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that lecithin is important in membranes. This is true because lecithin is a type of phospholipid, which is a fundamental component of cell membranes.

2. **Identifying Lecithin**: Lecithin is specifically known as phosphatidylcholine, which consists of a glycerol backbone, two fatty acid tails, a phosphate group, and a choline molecule. This structure is crucial for the formation of lipid bilayers in cell membranes.

3. **Role of Lecithin in Membranes**: Lecithin contributes to the structural integrity of membranes. It helps to create a semi-permeable barrier that allows selective passage of substances in and out of the cell.

4. **Understanding the Reason**: The reason provided states that lecithin has an amphipathic nature. This is also true. Amphipathic molecules have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.

5. **Explaining Amphipathic Nature**: In lecithin, the phosphate group (head) is hydrophilic, while the fatty acid tails are hydrophobic. This dual nature allows lecithin to form bilayers, which are essential for membrane structure.

6. **Conclusion**: Both the assertion and the reason are true. However, the reason does not directly explain why lecithin is important in membranes; it merely describes its structural properties.

7. **Final Answer**: Therefore, the correct answer is option B: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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