Biogeochemical cycles can be traced in

Which of the following processes is faster?

The world's most problematic aquatic weed is

Read the following statements carefully and answer the question given below:
$(1)$ $NPP = GPP - R$
$(2)$ Productivity of an ecosystem can be measured in $g/m^2/yr$ or $kcal/m^2/day$.
$(3)$ The total amount of energy produced by all producers in an ecosystem is called Gross Primary Productivity $(GPP)$.
$(4)$ The net primary productivity of the oceans is $55$ billion tons.
State the number of correct statements.

The given food web contains some missing organisms $A, B, C$ and $D$. Identify these organisms and select the correct answer.

The energy obtained from fossil fuels is essentially a product of which of the following?