Percentage of Photosynthetically Active Radiation $(PAR)$ that is captured by plants in the synthesis of organic matter is

Assertion $A$: Heat energy is available for the functioning of a system.
Reason $R$: Some amount of energy is lost during energy transformation.
Which option is correct for Assertion $A$ and Reason $R$?

In an ecosystem,if the Net Primary Productivity $(NPP)$ of the first trophic level is $100x \text{ kcal } m^{-2} yr^{-1}$,what would be the Gross Primary Productivity $(GPP)$ of the third trophic level of the same ecosystem?

During a food chain, the maximum energy is stored in:

What is the primary function of a grazing food chain?

In a food web,each successive trophic level has