Omnivores consume $.....$

What will happen if deer is missing in the food chain given below?
Grass $\rightarrow$ Deer $\rightarrow$ Tiger

In a food chain consisting of grass,insect,frog,and snake,what is the trophic level of the frog?

Pesticides like $DDT$ which are sprayed to kill pests on crops are found to be present in the soil,groundwater,water bodies etc. Explain how do they reach these places.

Differentiate between autotrophs,heterotrophs,and decomposers and give one example of each.

Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called