Assertion $A$: Living organisms obtain various molecules and elements from their environment.
Reason $R$: Living organisms synthesize components essential for their body.
Which option is correct for Assertion $A$ and Reason $R$?

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:

In which organ of the human body does glycogenolysis occur?

Column-$I$ contains some terms and Column-$II$ contains their meanings. Match them properly and choose the right answer.

Column-$I$	Column-$II$
$A$. Glycogenesis	$1$. Conversion of glycogen to glucose
$B$. Glycosuria	$2$. Conversion of glucose to glycogen
$C$. Gluconeogenesis	$3$. Excretion of glucose in urine
$D$. Glycogenolysis	$4$. Conversion of non-carbohydrate sources to glucose
	$5$. Conversion of glucose to starch

The given figures represent the nitrogenous bases of nucleic acids. Identify the correct group.

In a water molecule,at what angle are the $H - O - H$ bonds connected (in $^\circ$)?