The primary consumers sustain on:

Options

A. Gross primary production
B. Net primary production
C. Secondary production
D. Net community production

Answer

**Step-by-Step Solution:**

1. **Understanding Primary Consumers**: Primary consumers are organisms that primarily feed on producers, which are typically green plants or grasses. They are the second trophic level in an ecosystem.

2. **Role of Producers**: Producers, such as grass, utilize sunlight to create energy through photosynthesis. This energy is referred to as gross primary productivity (GPP).

3. **Energy Transfer to Primary Consumers**: When primary consumers, like deer, consume these producers, they obtain energy. However, not all energy from producers is transferred to primary consumers due to energy loss during respiration.

4. **Net Primary Productivity (NPP)**: The energy that is actually available to primary consumers after accounting for the energy lost through respiration is known as net primary productivity (NPP). It is calculated by subtracting the energy lost through respiration from the gross primary productivity.

5. **Conclusion**: Therefore, primary consumers sustain on the net primary productivity of producers, which is the energy available after respiratory losses.

**Final Answer**: Primary consumers sustain on the net primary productivity of producers.

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