Identify the correct type of food chain.
Dead animal $\rightarrow$ Blow fly maggots $\rightarrow$ Common frog $\rightarrow$ Snake

Find an incorrect statement for $DFC$ (Detritus Food Chain).

Some of the stages in the hydrarch succession are labelled as:
$I.$ Marsh meadow stage
$II.$ Reed swamp stage
$III.$ Submerged plant stage
$IV.$ Phytoplankton stage
$V.$ Submerged free floating plant stage
Identify the choice that represents the correct sequence of these stages.

In a grassland ecosystem, match the trophic levels with their correct example species:

$(a)$ 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:

The changes that occur in successive seral stages to reach a climax community are:
$I.$ Changes in the diversity of species of organisms.
$II.$ Increase in the number of species and organisms.
$III.$ Increase in the total biomass.
Choose the correct option.

Identify the possible link '$M$' in the following food chain.
Plant $\rightarrow$ Insect $\rightarrow$ $M$ $\rightarrow$ Snake $\rightarrow$ Eagle