Correct Option
The correct option is Primary productivity provides biomass available to herbivores and decomposers..
Explanation
Productivity in an ecosystem refers to the rate of biomass or organic matter generation. It is divided into two main categories based on the trophic level involved:
- Primary Productivity: The rate at which biomass is produced by producers (plants/autotrophs) via photosynthesis.
- Secondary Productivity: The rate of formation of new organic matter by consumers (heterotrophs).
Statement-wise Analysis
- Primary productivity provides biomass available to herbivores and decomposers. is Correct. Specifically, Net Primary Productivity (NPP) is the amount of biomass remaining in plants after they have utilized some energy for respiration. This stored biomass is what is available for consumption by herbivores (primary consumers) and decomposers. While the statement uses the broad term "Primary Productivity," it correctly describes the function of NPP within that category.
- Primary productivity is the rate of new organic matter formation by consumers. is Incorrect. The rate of formation of new organic matter by consumers is defined as Secondary Productivity, not Primary Productivity.
- Secondary productivity is the rate of biomass production by plants. is Incorrect. The rate of biomass production by plants (producers) is defined as Primary Productivity. Secondary productivity relates strictly to consumers.
- Secondary productivity equals Gross Primary Productivity minus respiration. is Incorrect. Gross Primary Productivity (GPP) minus respiration losses (R) equals Net Primary Productivity (NPP), not Secondary Productivity. The equation is: NPP = GPP - R.
Key Takeaway
Primary Productivity is associated with producers (plants), while Secondary Productivity is associated with consumers. Net Primary Productivity (NPP) is the actual biomass available for transfer to the next trophic level in the food chain.