The group of organisms oxidising various inorganic substances such as nitrates, nitrites and ammonia using the released energy for their ATP production are-

Options

A. Chemoheterotrophic bacteria
B. Chemosynthetic autotrophic bacteria
C. Photoautotrophic bacteria
D. Saprophytic bacteria

Answer

To answer the question about the group of organisms that oxidize various inorganic substances such as nitrates, nitrites, and ammonia for ATP production, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Process**: The question describes a process where organisms oxidize inorganic substances to produce energy. This process is known as **chemoautotrophy** or **chemosynthesis**.

2. **Understand the Organisms Involved**: The organisms that perform this type of metabolism are typically **chemoautotrophs**. They derive energy from the oxidation of inorganic compounds rather than from sunlight (as in photosynthesis).

3. **Examples of Inorganic Substances**: The inorganic substances mentioned in the question include nitrates, nitrites, and ammonia. These are often used by certain bacteria in their metabolic processes.

4. **Identify Specific Groups**: The specific groups of organisms that oxidize these substances include:
- **Nitrifying bacteria**: These bacteria oxidize ammonia to nitrites and then to nitrates.
- **Denitrifying bacteria**: These can reduce nitrates to nitrogen gas, but they also play a role in the nitrogen cycle.
- **Ammonia-oxidizing bacteria**: These specifically oxidize ammonia into nitrites.

5. **Conclusion**: Therefore, the group of organisms that oxidize various inorganic substances such as nitrates, nitrites, and ammonia using the released energy for ATP production are known as **chemoautotrophs** or more specifically, **nitrifying bacteria**.

### Final Answer:
The group of organisms oxidizing various inorganic substances such as nitrates, nitrites, and ammonia for ATP production are called **chemoautotrophs**.