Enzymes, vitamins and hormones are common in

Options

A. Being proteinaceous
B. Being synthesised in the body of organisms
C. Enhancing oxidative metabolism
D. Regulating metabolism.

Answer

To answer the question "Enzymes, vitamins and hormones are common in", we will analyze the options provided and determine which one is correct based on the characteristics of enzymes, vitamins, and hormones.

### Step-by-Step Solution:

1. **Understanding Enzymes, Vitamins, and Hormones**:
- **Enzymes**: These are biological catalysts that speed up chemical reactions in the body. They are primarily proteins.
- **Vitamins**: These are organic compounds that are essential for various metabolic processes. They often act as coenzymes but are not proteins themselves.
- **Hormones**: These are signaling molecules that regulate physiological processes. They can be proteins (like insulin) or steroids (like cortisol).

2. **Analyzing the Options**:
- **Option 1: Being proteinaceous**:
- Enzymes are proteinaceous, and some hormones are too, but vitamins are not. Therefore, this option is incorrect.

- **Option 2: Being synthesized in the body**:
- Enzymes and hormones are synthesized in the body, but vitamins must be obtained from the diet as the body cannot synthesize them. Thus, this option is incorrect.

- **Option 3: Enhancing oxidative metabolism**:
- Not all enzymes, vitamins, and hormones enhance oxidative metabolism. This is a specific function that does not apply to all three categories. Hence, this option is incorrect.

- **Option 4: Regulating metabolism**:
- Enzymes play a crucial role in metabolic pathways, hormones regulate various metabolic functions (like growth, metabolism, and homeostasis), and vitamins often serve as coenzymes that assist in metabolic reactions. Therefore, this option is correct.

3. **Conclusion**:
- The correct answer is **Option 4: Regulating metabolism**. Enzymes, vitamins, and hormones all play significant roles in regulating the body's metabolism.