In the food chain
Grass $\rightarrow$ Deer $\rightarrow$ Lion
operating in a forest,what will happen if all the
$(a)$ lions are removed?
$(b)$ deers are removed?

(N/A) If all lions are removed,the population of deer will increase significantly due to the lack of predators. This overpopulation will lead to overgrazing,causing a depletion of grass,which may eventually result in soil erosion.
$(b)$ If all deer are removed,the lions will lose their primary food source,leading to a decline in the lion population due to starvation. Conversely,the amount of grass will increase as there are no herbivores to consume it.