Which of the following has the largest biomass of autotrophs in the world's oceans?

Which of the following trophic levels are occupied by a sparrow?

Which of the following are primary consumers in a food chain?

Given below is a list of autotrophs and heterotrophs. With your knowledge about food chain,establish various linkages between the organisms on the principle of 'eating and being eaten'. What is this inter-linkage established known as?
Algae,hydrilla,grasshopper,rat,squirrel,crow,maize plant,deer,rabbit,lizard,wolf,snake,peacock,phytoplankton,crustaceans,whale,tiger,lion,sparrow,duck,crane,cockroach,spider,toad,fish,leopard,elephant,goat,nymphae,spirogyra.

The oxygen concentration at the floor of the deep ponds and lakes is very low because of the

The average price tag for ecosystem services has been placed at around $.........$ per year.