State the various steps involved in the process of photosynthesis.

Gas $A$, which is the major cause of global warming, combines with hydrogen oxide $B$ in nature in the presence of an environmental factor $C$ and a green material $D$ to form a six-carbon organic compound $E$ and a gas $F$. The gas $F$ is necessary for breathing. $(a)$ What is gas $A$? $(b)$ What is the common name of $B$? $(c)$ What do you think could be $C$? $(d)$ What is material $D$? Where is it found? $(e)$ Name the organic compound $E$. $(f)$ What is gas $F$? Name the natural process during which it is released.

Stomata of desert plants remain closed during the day. Explain how and when they take up $CO_2$ to perform photosynthesis?

The largest gland of the human body is . . . . . . .

Choose the forms in which most plants absorb nitrogen.
$(i)$ Proteins
$(ii)$ Nitrates and Nitrites
$(iii)$ Urea
$(iv)$ Atmospheric nitrogen

Select the correct statement.