The second trophic level in a pond ecosystem is ..........

$A$ - $80\%$ of total global carbon is dissolved in the oceans.
$R$ - The dry weight of organisms consists of $49\%$ carbon.

Choose the correct statement regarding trophic levels in an ecosystem.

Energy enters an ecosystem through

Consider the following statements about the carbon cycle and choose how many statements are correct?
$(a)$ The atmosphere contains $71\;\%$ of the total global carbon.
$(b)$ Decomposers contribute substantially to the $CO_2$ pool by processing waste materials and dead organic matter from land or oceans.
$(c)$ $4 \times 10^{13}\; kg$ of carbon is fixed through photosynthesis annually.
$(d)$ There is no respiratory input into the atmosphere.
$(e)$ Carbon constitutes $49\;\%$ of the dry weight of organisms.

The amount of photosynthetically active radiation captured by plants is