NCERT Questions for Class 12 Chemistry Chapter 10 – Biomolecules

Important Questions with Solutions of Class 12 Chemistry Chapter 10 – Biomolecules

Short Answer Questions

1) Define the amphoteric nature of amino acids.

Ans – In a molecule, amino acids contain an acid (carboxyl group) & a base (amino group). They complement each other by neutralizing aqueous-based solutions. The carboxyl group loses one proton & the amino group gains one proton. Amino acids react with acids & bases in their zwitter ionic form, showing their amphoteric nature of amino acids.

2) What defines the prefix ‘D’ in the compound D-(+)-glucose?

Ans – The hydroxyl group present in the chiral carbon is far from the massive oxidized carbon (Aldehyde group in this case) concerning glyceraldehyde is called D(+) glucose. The hydroxyl group present on the right-hand side can be depicted by ‘D’.

3) (i) Sucrose is deemed as a non-reducing sugar. Why?

Ans – Sucrose is a non-reducing sugar due to its glycosidic link over C-1of -glucose & C-2of -fructose having 2 monosaccharide parts of glucose & fructose. Hence, sucrose contains zero free aldehyde/ketone adjacent to the CHOH cluster making sucrose a non-reducing sugar.

(ii) Explain the glycosidic linkage variant available in sucrose.

Ans – Sucrose is a disaccharide with a molecule formed from 2 monosaccharides named glucose & fructose. An ether bond between these 2 units is created based on the C-1on the glucosyl subunit & C-2on the fructosyl unit.

4) Mention the difference between an oligosaccharide & a polysaccharide.

Ans – The major variations between oligosaccharides & polysaccharides are as follows:

Oligosaccharide	Polysaccharide
An oligosaccharide is a saccharide polymer has restricted monosaccharides (3 to 10 simple sugars). Cell recognition & binding can be done by oligosaccharide.	Polysaccharides are polymeric carbohydrates with long chains of monosaccharide units connected by glycosidic links.
For example: sucrose, lactose, maltose, and more.	For example: starch, glycogen, and more.

3 Mark Questions

1) During electrolysis in an acidic solution, the amino acids move toward the cathode but in an alkaline solution, they move toward the anode.

Ans – An amino acid remains as a dipolar ion. During electrolysis, when an ion changes into a positive ion in an acidic medium, it moves toward the cathode meanwhile ion changes to a negative ion in a base, it moves over through an anode.

In an acidic solution, the coo+ group of zwitter ion created during α -amino acid is protonated & NH3+ clusters remain unaltered whereas the basic solution deprotonation changes from NH3+ to NH2 & COO- remains the same.

2) Give your explanation on:

(a) Denaturation of protein

Ans – Denaturation refers to proteins/nucleic acids that lose their original feature by revealing to various external environments or chemical reactions, including more acid or base, a powerful inorganic salt, an organic solvent, extreme outer radiation, or excessive heat. When proteins are denatured from a live functioning cell, the cell operation gets deviated resulting in the death of the cell.

b) Specificity of an enzyme

Ans – Enzymes exhibit specificity regarding reactions that they catalyze. Most enzymes are absolutely specificity. For instance, one enzyme will catalyze a single reaction alone. The remaining enzymes will exhibit a preference for a particular chemical bond or functional cluster. There are 4 specificity variants: linkage specificity, absolute specificity, group specificity & stereochemical specificity.

3) Explain hypervitaminosis & avitaminosis.

Ans – Hypervitaminosis is a disease where the human body contains more than the required amount of vitamins A & D. It can be obtained if one has excess consumption of vitamins or uses medicines for acne for a long period. Vision problems, skin disorders, or bone pain can be the visible symptoms of hypervitaminosis and are hazardous for the human liver by creating pressure on the human brain in the long run. Avitaminosis is a mix of various diseases resulting from vitamin deficiency. It can occur due to long-lasting diarrhoea or extensive sweating, or when the need for vitamins is surged because of rapid growth in infancy or pregnancy.

4) Existence of DNA & RNA in the human body. What does it depict?

Ans – DNA has 3 distinct functions: genetics, immunology & shape. Each of them focuses on the sugar-phosphate backbone & bases in multiple methods.

Genetic information is encrypted by the nucleotide process over the backbone. The 4 main specifications of DNA are Replication, securing information, mutation/recombination & gene expression.

RNA: Facilitates the conversion of DNA into proteins. It acts as adaptor molecule during protein synthesis since the messenger transfers data from the DNA to the ribosomes.

In any active living cell, the RNAs play the carrier role in passing the genetic information.