Select the incorrect statement .

Options

A. Energy always decreases with increase in trophic level.
B. Secondary succession is faster than primary succession.
C. Ecological pyramids cannot explain all the vital functions of any ecosystem.
D. The amount of nutrients present in the soil at any given time is referred to as the standing crop.

Answer

To solve the question of selecting the incorrect statement, let's analyze each statement one by one:

### Step 1: Analyze the First Statement
**Statement:** Energy always decreases as the trophic levels increase.

**Explanation:** This statement is true. In an energy pyramid, as you move from producers (like plants) to primary consumers (herbivores) and then to secondary consumers (carnivores), the amount of energy available decreases. This is due to energy loss at each trophic level primarily through metabolic processes and heat.

**Hint:** Remember that energy transfer in ecosystems is inefficient, leading to energy loss at each level.

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### Step 2: Analyze the Second Statement
**Statement:** Secondary succession is faster than primary succession.

**Explanation:** This statement is also true. Secondary succession occurs in areas where a disturbance has destroyed an existing community but left the soil intact. Since soil and nutrients are already present, recovery is faster compared to primary succession, which starts from bare rock or a lifeless area.

**Hint:** Think about the conditions that allow for quicker recovery in secondary succession compared to primary succession.

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### Step 3: Analyze the Third Statement
**Statement:** Ecological pyramids cannot explain all the vital functions of any ecosystem.

**Explanation:** This statement is true. Ecological pyramids, which represent the biomass, energy, or number of organisms at each trophic level, have limitations. They do not account for decomposers, which play a crucial role in nutrient cycling, and they may not accurately represent organisms that occupy multiple trophic levels.

**Hint:** Consider the roles of decomposers and the complexity of food webs when evaluating this statement.

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### Step 4: Analyze the Fourth Statement
**Statement:** The standing crop has been defined as the amount of nutrient which is present in the soil at any given time.

**Explanation:** This statement is incorrect. The standing crop refers to the total biomass of living organisms (usually plants) in a given area at a specific time, not the nutrients in the soil. It represents the amount of organic matter present, while soil nutrients are a separate concept.

**Hint:** Distinguish between biomass (living matter) and soil nutrients (non-living matter) to identify the incorrect definition.

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### Conclusion
After analyzing all four statements, the incorrect statement is the fourth one. Therefore, the correct answer to the question is:

**Answer:** Option 4 is the incorrect statement.