The total energy fixed by a gram plant (Cicer arietinum) in an ecosystem on the whole is called
Choose incorrect option w.r.t. amount of living material present in different trophic levels at a given time
$A$- Grasshopper is included in primary consumer.
$R$- Fishes and birds are included in top carnivore.
Consider the following statements concerning food chains.
$I$. Removal of $80\; \%$ tigers from an area resulted in greatly increased growth of vegetation.
$II.$ Removal of most of the carnivores resulted in an increased population of deers.
$III.$ The length of food chains is generally limited to $3$ to $4$ trophic levels due to energy loss.
$IV.$ The length of food chains may vary from $2$ to $8$ trophic levels.
Which two of the above statements are correct?