NEET Chemistry: Chemistry - Biomolecules questions with solutions

Q1. Invert sugar is:

1. a type of cane sugar
2. optically inactive form of sugar
3. mixture of glucose and galactose
4. mixture of glucose and fructose in equimolar quantities

Answer: mixture of glucose and fructose in equimolar quantities

Invert sugar is produced by hydrolysis of sucrose, giving equal moles of glucose and fructose. The name comes from the inversion of optical rotation after hydrolysis.

Q2. Cellulose is a?

1. hexapolysaccharide.
2. pentapolysaccharide.
3. tripolysaccharide.
4. None of these.

Answer: hexapolysaccharide.

Cellulose is a polysaccharide made of repeating glucose units, and glucose is a hexose (six-carbon sugar). So cellulose is classified as a hexapolysaccharide.

Q3. In the figure below, the plane drawn behind the peptide bond indicates the:

1. absence of rotation around \( C-N \) bond because of its partial-double bond character
2. plane of rotation around the \( C-N \) bond
3. region of steric hindrance determined by the large \( C=O \) group
4. none of the above

Answer: absence of rotation around \( C-N \) bond because of its partial-double bond character

The peptide bond has resonance between the carbonyl and amide nitrogen, giving the C–N bond partial double-bond character. That makes the bond planar and prevents free rotation, which is what the figure is indicating.