What percentage of $PAR$ (Photosynthetically Active Radiation) is captured by plants?

$10 \%$ law of energy transfer was given by

In an ecosystem,there is a flow of energy at different trophic levels. This is as follows:

“The energy flow in the ecosystem follows the second law of thermodynamics.” Explain.

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 $R$?

The percentage of energy transferred to the higher trophic level in a food chain is ....... (in $\%$)