One similarity between enzyme and hormones is that both

Options

A. are proteins
B. act at a wide range of pH
C. are used in minute amount
D. can be used again and again

Answer

To determine one similarity between enzymes and hormones, we will analyze the provided options step by step.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) Both are proteins
- B) Both act in a wide range of pH
- C) Both are used in minute amounts
- D) Both can be used again and again

2. **Evaluate Option A (Both are proteins)**:
- Enzymes are primarily proteins, but there are exceptions like ribozymes, which are made of RNA.
- Hormones can also be non-protein in nature; for example, steroid hormones like progesterone and estrogen are derived from cholesterol.
- Conclusion: This option is **not a valid similarity**.

3. **Evaluate Option B (Both act in a wide range of pH)**:
- Enzymes have specific pH ranges in which they function optimally, and they do not necessarily work in a wide range of pH.
- Hormones also have specific conditions under which they operate effectively.
- Conclusion: This option is **not a valid similarity**.

4. **Evaluate Option C (Both are used in minute amounts)**:
- Both enzymes and hormones are effective in very small quantities. Enzymes catalyze reactions without being consumed, and hormones are released in small amounts to elicit responses in target cells.
- Conclusion: This option is a **valid similarity**.

5. **Evaluate Option D (Both can be used again and again)**:
- Enzymes can indeed be reused multiple times in reactions without being altered.
- However, hormones are typically consumed in the process of signaling and are not reused in the same manner.
- Conclusion: This option is **not a valid similarity**.

### Final Answer:
The correct similarity between enzymes and hormones is that **both are used in minute amounts** (Option C).

---