Chemosynthetic bacteria obtain energy from

Options

A. Sun
B. Infra red rays
C. Organic substances
D. Inorganic chemicals

Answer

### Step-by-Step Solution:

1. **Understanding Chemosynthetic Bacteria**:
- Chemosynthetic bacteria are a type of autotroph, which means they can produce their own food. They do this through a process that does not involve sunlight, unlike photosynthetic organisms.

2. **Types of Autotrophs**:
- There are two main types of autotrophs:
- **Photosynthetic autotrophs**: These organisms, such as plants, use sunlight to convert carbon dioxide and water into glucose and oxygen.
- **Chemosynthetic autotrophs**: These organisms, including chemosynthetic bacteria, derive energy from chemical reactions involving inorganic substances.

3. **Energy Source for Chemosynthetic Bacteria**:
- Chemosynthetic bacteria obtain energy from the oxidation of inorganic substances. This means they utilize inorganic chemicals (such as hydrogen sulfide, ammonia, or ferrous iron) to produce energy.

4. **Conversion Process**:
- The energy obtained from these inorganic substances is used to convert them into organic compounds. This process is essential for the survival of these bacteria and contributes to the ecosystem by providing organic matter.

5. **Identifying the Correct Option**:
- Given the options:
- 1) Sun
- 2) Infrared rays
- 3) Organic substances
- 4) Inorganic substances
- The correct answer is **option 4: inorganic substances**, as this is the source from which chemosynthetic bacteria derive their energy.

### Final Answer:
Chemosynthetic bacteria obtain energy from **inorganic substances**.