The second trophic level of longer food chains in a lake is:

Options

A. Phytoplankons
B. Zooplanktons
C. Benthos
D. Fishes.

Answer

To solve the question regarding the second trophic level of longer food chains in a lake, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Trophic Levels**:
- Trophic levels refer to the position of organisms in a food chain. The first level consists of producers, the second level consists of primary consumers, and subsequent levels consist of secondary consumers and so on.

2. **Identify the Primary Producers in a Lake Ecosystem**:
- In a lake ecosystem, the primary producers are typically phytoplankton (or photoplankton). These organisms are capable of photosynthesis and form the base of the food chain.

3. **Determine the Primary Consumers**:
- The primary consumers are organisms that feed on the primary producers. In the case of a lake ecosystem, zooplankton are the primary consumers that feed on phytoplankton.

4. **Identify the Second Trophic Level**:
- Since phytoplankton are the primary producers (first trophic level), and zooplankton feed on them, zooplankton represent the second trophic level in the food chain.

5. **Evaluate the Other Options**:
- Benthos: These are organisms that live at the bottom of the water bodies and do not represent the second trophic level.
- Fishes: These are typically secondary consumers that feed on zooplankton, thus they do not represent the second trophic level either.

6. **Conclude the Correct Answer**:
- Based on the analysis, the correct answer to the question is **zooplankton**, which represents the second trophic level in a lake ecosystem.

### Final Answer:
The second trophic level of longer food chains in a lake is **zooplankton**.

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