The hydrological cycle comprises two overlapping cycles.

Select the correct option for the following processes:
$P$ - Formation of organic components from inorganic components
$Q$ - Formation of inorganic components from organic components
Select the correct option for $P$ and $Q$.

Which of the following is $NOT$ a functional unit of an ecosystem?

Which of the following characteristics of an ecosystem is naturally provided to human society?

Match the trophic levels with their correct species examples in a grassland ecosystem.

$(a)$ Fourth trophic level	$(i)$ Crow
$(b)$ Second trophic level	$(ii)$ Vulture
$(c)$ First trophic level	$(iii)$ Rabbit
$(d)$ Third trophic level	$(iv)$ Grass

Select the correct option:

What changes are observed in energy at successive trophic levels in a food chain?