The mass of living material.at a trophic level at a particular time is called

Options

A. Net primary productivity
B. Standing Crop
C. Gross primary productivity
D. Standing state

Answer

To solve the question regarding the mass of living material at a trophic level at a particular time, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**:
- We need to identify what "mass of living material" refers to in ecological terms. This is typically associated with biomass at a specific trophic level.

2. **Identifying the Options**:
- The options provided are:
1. Net Primary Productivity (NPP)
2. Standing Crop
3. Gross Primary Productivity (GPP)
4. Standing State

3. **Analyzing Each Option**:
- **Net Primary Productivity (NPP)**: This refers to the amount of organic matter (biomass) produced by plants after accounting for respiration. It is not a measure of the mass at a specific time but rather a rate of production over time.
- **Standing Crop**: This term refers to the total mass of living material (biomass) present at a given trophic level at a specific time. This is what the question is asking for.
- **Gross Primary Productivity (GPP)**: This is the total amount of organic material produced by photosynthesis before any is used for respiration. Like NPP, it is a rate, not a mass at a specific time.
- **Standing State**: This term typically refers to the inorganic mass in an ecosystem, not the organic mass of living organisms.

4. **Conclusion**:
- After analyzing the options, the correct answer is **Standing Crop**, as it directly refers to the mass of living material at a trophic level at a particular time.

### Final Answer:
The mass of living material at a trophic level at a particular time is called **Standing Crop**.

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