Which of the following statements about NPP & GPP is true?

• A. GPP is the total energy captured by producers, NPP is the amount of energy they convert to biomass.
• B. Both GPP & NPP can be heavily influenced by climate.
• C. The NPP in an ecosystem equates to how much food is available for primary consumers.
• D. All of the above are true.

Answer: (D)

Verified step by step guidance

1. Understand the definitions: Gross Primary Productivity (GPP) is the total amount of energy captured by producers in an ecosystem through photosynthesis. Net Primary Productivity (NPP) is the energy that remains after producers have used some of this energy for their own respiration. It is the energy available for growth and reproduction, and ultimately for consumption by herbivores (primary consumers).
2. Analyze the first statement: 'GPP is the total energy captured by producers, NPP is the amount of energy they convert to biomass.' This statement is true because NPP is calculated as GPP minus the energy used by producers for respiration, which is then converted into biomass.
3. Evaluate the second statement: 'Both GPP & NPP can be heavily influenced by climate.' This is true because factors such as temperature, sunlight, and precipitation can affect the rate of photosynthesis and respiration, thereby influencing both GPP and NPP.
4. Consider the third statement: 'The NPP in an ecosystem equates to how much food is available for primary consumers.' This is true because NPP represents the energy stored as biomass, which is the energy available to herbivores and other primary consumers.
5. Conclude that all the statements are true, as each one accurately describes aspects of GPP and NPP in an ecosystem. Therefore, the correct answer is 'All of the above are true.'