Assertion :- It is the metabolic, physiological or environmental conditions that regulate the expression of genes.
Reason : The genes in a cell are expressed to perform a particular function or a set of functions.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are trur but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is Flase.
D. If both Assertion & Reason are false.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that metabolic, physiological, or environmental conditions regulate the expression of genes. This means that various factors can influence whether a gene is turned on or off, which in turn affects how proteins are produced in the cell.

2. **Understanding the Reason:**
- The reason states that genes in a cell are expressed to perform a particular function or a set of functions. This implies that genes are not just randomly expressed; they are activated to carry out specific roles necessary for the cell's survival and function.

3. **Connecting Assertion and Reason:**
- Both statements are interconnected. The assertion explains the conditions that influence gene expression, while the reason describes the purpose of gene expression. For example, if a cell requires a specific enzyme to metabolize a nutrient, the gene coding for that enzyme will be expressed under the right conditions (as stated in the assertion).

4. **Levels of Gene Regulation:**
- Gene expression can be regulated at multiple levels, including:
- **Transcriptional Level:** The process of converting DNA to mRNA.
- **Post-transcriptional Level:** Processing of mRNA (like splicing).
- **Translational Level:** The synthesis of proteins from mRNA.
- **Post-translational Level:** Modifications to proteins after they are made.

5. **Examples of Gene Expression Regulation:**
- A classic example is the lac operon in E. coli, where the presence of lactose in the environment triggers the expression of genes needed to metabolize it. If lactose is absent, the genes are not expressed.

6. **Conclusion:**
- Both the assertion and reason are true, and the reason accurately explains the assertion. Therefore, the correct answer is that both statements are true and the reason is the correct explanation of the assertion.

**Final Answer:**
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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