Insulin is a biochemically active peptide harmone secreted by pancreas.

Glucose is present is pyranose form ( six membered cyclic structure ).

Carboxylic acids are stronger acids than $$ - NH_3^ + ,$$  therefore $$X$$ is the strongest acid. Since $$-COOH$$   has $$-I$$  effect which decreases with distance, therefore, effect is more pronounced on $$Z$$ than on $$Y.$$  As a result $$Z$$ is more acidic than $$Y.$$  Therefore, overall order of acid strength is $$X >Z > Y.$$

Sucrose contains glycosidic link between $${C_1}$$  of $$\alpha {\text{ - }}D$$  glucose and $${C_2}$$  of $$\beta {\text{ - }}D{\text{ - }}$$  fructose.
$${C_{12}}{H_{22}}{O_{11}} + {H_2}O \to {\text{Glucose + Fructose}}$$

Amylopectin is a polymer of $$\alpha - D - $$  glucose.

Cellulose is a linear polymer of $$\beta - D - $$  glucose in which $${C_1}$$  of one glucose unit is connected to $${C_4}$$  of the other through $$\beta - D$$  glucosidic linkage. It does not undergo hydrolysis easily. However on heating with dilute $${H_2}S{O_4}$$  under pressure. It does undergo hydrolysis to give only $$D - $$ glucose.
\[\left( {{C}_{6}}{{H}_{10}}{{O}_{5}} \right)n+n{{H}_{2}}O\xrightarrow{H+}\underset{D\text{-Glucose}}{\mathop{n{{C}_{6}}{{H}_{12}}{{O}_{6}}}}\,\]

The hydrogen bonding plays important role in secondary structure.

Since sucrose is dextrorotatory while hydrolysis product of sucrose, having equimolar mixture of glucose and fructose, is laevorotatory. Hence the hydrolysed product of sucrose is known as invert sugar and the hydrolysis of sucrose is known as inversion.

Since $$GC$$  base pair having three $$H$$ - bonds is more stable than $$AT$$  base pair having two $$H$$ - bonds, therefore, $$DNA,$$  $$B$$  has higher melting point than $$DNA,$$  $$A.$$

(A) and (D) are $${L^ - }$$  sugar but (A) gives an optically active dibasic acid.