Identify the statement which is incorrect.

Given below are two statements:
Statement $I$: $A$ protein is imagined as a line,the left end represented by the first amino acid ($N$-terminal) and the right end represented by the last amino acid ($C$-terminal).
Statement $II$: Adult human haemoglobin consists of $4$ subunits (two subunits of $\alpha$ type and two subunits of $\beta$ type).
In the light of the above statements,choose the correct answer from the options given below:

$\beta$-carotene is a ...... .

In metabolic processes,the energy obtained by the cell is immediately stored in which form?

The conversion of fatty acids into $CO_2$ and $H_2O$ is called $........$ process,and the synthesis of fatty acids from acetyl $CoA$ is called $........$ process.

In the given figure,what are '$X$' and '$Y$' respectively?