Read the following statements about enzymes.
Which among them are correct?
I. The mechanism by which enzymes work is known as lock and key.
II. They denature at high temperatures.
III. They are mostly proteins having a tertiary structure.
IV. They may be assisted by vitamins and minerals.

Options

A. I , II and III only
B. I , II , III and IV
C. II and IV only
D. I , II and IV only

Answer

To solve the question about the correctness of the statements regarding enzymes, we will analyze each statement one by one:

### Step-by-Step Solution:

1. **Statement I: The mechanism by which enzymes work is known as lock and key.**
- This statement is **correct**. The "lock and key" model describes how the enzyme (the lock) has a specific shape that fits a specific substrate (the key). This model illustrates the specificity of enzymes for their substrates.

**Hint:** Think of how a key fits into a lock; only the right key can open the lock, similar to how a substrate fits into an enzyme.

2. **Statement II: They denature at high temperatures.**
- This statement is **correct**. Enzymes are proteins that can lose their functional shape (denature) when exposed to high temperatures. Most enzymes function optimally at temperatures around 37-40 degrees Celsius, and excessive heat can lead to denaturation.

**Hint:** Remember that proteins are sensitive to temperature changes, and extreme heat can cause them to lose their structure.

3. **Statement III: They are mostly proteins having a tertiary structure.**
- This statement is **incorrect**. While many enzymes are proteins, their functional structure is not solely tertiary. Enzymes can have primary, secondary, tertiary, and quaternary structures depending on their complexity. The statement is misleading as it implies that they are only tertiary.

**Hint:** Consider the different levels of protein structure; enzymes can exhibit more than just tertiary structure.

4. **Statement IV: They may be assisted by vitamins and minerals.**
- This statement is **correct**. Enzymes often require cofactors, which can be vitamins or minerals, to function properly. These cofactors help in the catalytic activity of the enzyme.

**Hint:** Think about how some vitamins and minerals play crucial roles in biochemical reactions as helpers for enzymes.

### Conclusion:
Based on the analysis:
- Statements I, II, and IV are correct.
- Statement III is incorrect.

Thus, the correct answer is that statements I, II, and IV are correct.

### Final Answer:
The correct statements about enzymes are I, II, and IV.

**Option D** is the correct choice as it includes statements 1, 2, and 4.