Which of the following is a primary consumer in a maize field ecosystem?

Amount of inorganic substances present in an ecosystem is . . . . . . Energy flow is a . . . . . . feature of ecosystem.

Which of the following statements is incorrect regarding the phosphorus cycle?

Identify the organisms $I, II, III$ and $IV$ in the given food web.
$I$ | $II$ | $III$ | $IV$

Read the given statements and determine how many of them are correct.
$(1)$ Secondary succession depends on the condition of the soil and the availability of water.
$(2)$ Air,water,and land are abiotic factors of an ecosystem.
$(3)$ The structure of an ecosystem includes the cycling of nutrients and the unidirectional flow of energy.
$(4)$ The primary source of energy in an ecosystem is the sun.

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