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The functions of polysaccharides are: 

(i) Starch and glycogen are the major storage food of organic world. 

(ii) On hydrolysis, carbohydrates provide both energy and carbon chains. 

(iii) Chitin is the structural carbohydrate of fungal walls and exoskeleton of arthropods. 

(iv) Cellulose is the structural substance of cell walls in most of the plants. 

(v) Cellulose is economically important in the production of furniture, shelter, fuel, paper, textiles, ropes, rayon, cellophane, plastics etc. 

(vi) Mucilage present as a protective coating around aquatic plants, bacteria, blue-green algae etc., is derived from polysaccharides.

(vii) Mucopolysaccharides present inside human body are keratin sulphate, chondroitin sulphate and hyaluronic acid. They have several functions - lubrication of ligaments and tendons, providing strength and flexibility to skin etc. 

(viii) Some mucopolysaccharides have medicinal and other commercial importance e.g., husk of Plantago ovata, mucilage of Aloe, and alginic acid. 

(ix) Pectins are commercial jelly agents.

It is a combination of nitrogenous base and pentose sugar.

Glycogen is animal starch.

(A) sugar and base

A nucleotide is a combination of nucleoside and phosphoric acid. 

Ribose  sugar

1. According to Watson and Crick, DNA molecule consists of two strands twisted around each other in the form of a double helix. 

2. The two strands i.e. polynucleotide chains are supposed to be in opposite direction so end of one chain having 3′ lies beside the 5′ end of the other. 

3. One turn of the double helix of the DNA measures about 34A. 

4. It consists paired nucleotides and the distance between two neighboring pair nucleotides is 3.4A. 

5. The diameter of the DNA molecule has been found be 20A.

1. Nucleotide is a unit which consists of a sugar, phosphate and a base. Nucleotides are basic units of nucleic acids. 

2. The nitrogen base and a sugar form a nucleoside. In a nucleoside, nitrogenous base is attached to the first carbon atom (C-1) of the sugar and when a phosphate group gets attached with that of the carbon (C-5) atom of the sugar molecule a nucleotide molecule is formed. 

3. The names of all nucleotides are:

Phosphodiester

Waxes an example of simple lipid.

Butyric acid, Stearic acid. 

Ole’s acid and Linoleic acid.

The correct answer is (A) Oxidoreductases

(b) Single stranded and unstable

(b) Rosalind Franklin

(i) Mucopolysaccharides are the slimy substances or mucilages which possess acidic or aminated polysaccharides formed from galactose, mannose, sugar derivatives and uronic acids. 

(ii) They are found inside the plant cell walls, outside the cells or bodies of bacteria, bluegreen algae, cementing layer between cells, inside body fluids, connective tissues and cartilages.

Two types of biomolecules are

Enzymes-characteristics: 

(i) Approximately all the enzymes are proteinaceous in nature. An enzyme/protein has a primary structure (amino acid sequence of protein). Enzyme like protein has secondary and the tertiary structure. 

(ii) The backbone of protein chain folds upon itself, chain criss-crosses itself and so several crevices or pockets are made out. One pocket is known as ‘active site'. So the enzymes, through their active site, catalyse reactions at a high rate.

(iii) The enzymes get denatured at a high temperatures (above 40°C). The enzymes isolated from organisms who live under extremely high temperatures e.g., hot vents and sulphur springs, are stable and retain their catalytic power at high temperatures (upto 80°-90°C).

(1) Primary metabolities : Metabolites which are found in animal tissues. They play specific role in normal physiological process. e.g., carbohydrates, protein, fats. 

(ii) Secondary metabolites : These are metabolites found in plant, fungal and microbial cells as a by product of main metabolic reactions. e.g. Alkaloids, rubber, terpenoides, essential oils, etc.

The modern system of enzyme classification was introduced by International Union of Biochemistry. 

It grouped enzymes into the following six categories : 

(i) Oxidoreductases : They take part in oxidation and reduction reactions or transfer of electrons. 

(ii) Transferases : They transfer group from one molecule to another e.g., glutamate pyruvate transaminase. 

(iii) Hydrolases : They break up large molecules into smaller ones with the help of hydrogen and hydroxyl groups of water molecules. The phenomenon is called hydrolysis. 

(iv) Lyases : The enzyme cause cleavage, removal of groups without hydrolysis, addition of groups to double bonds or reverse. e.g. aldolase. 

(v) Isomerase : The enzyme causes rearrangment of molecular structure to effect isomeric changes. These are of three types-isomerases, epimerases, mutase. 

(vi) Ligases : The enzyme catalyse bonding of two chemicals with the help of energy obtained from ATP. Е.g. pyruvate carboxylase.

Nucleosides are compounds having nitrogen bases attached to a sugar.

Nucleosides occurring in RNA are:

• Adenosine
• guanosine
• cytidine
• and uridine

Starch consists of amylose and amylopectin.Amylose is a linear polymer of α-D –glucose whereas cellulose is a linear polymer of β- D –glucose .In amylose, C-1 of one glucose unit is connected to C-4 of theother through α-glycosidic linkage.

(i) Invert sugar:-An equimolar mixture of glucose and fructose is called invert sugar. 

(iii) If more than 10 α-amino acid are joined together by peptide bond the polyamide thus formed is called polypeptides.

(a) Polysaccharides are tesrthe carbohydrates which on hydrolysis give a large number of molecules of monosaccharides. For example, starch, cellulose. 

(b) When a protein is in its native form is subjected to a change, change in temp. or pH , hydrogen bond is disturbed. Due to this globules unfold and helix got uncoiled and protein loses its biological activities. This is called denaturation of protein. 

(c) α-Amino acid which are required for health and growth of human being but are not synthesized by human body are called essential amino acid. eg:- valine, leucine, etc.

Sickle Cell Anaemia:

Haemoglobin, the molecule in the blood that carries oxygen consists of 574 amino acid units. Changing just one specific amino acid in the sequence results in defective haemoglobin found in patients suffering from sickle cell anaemia. In these patients the defective haemoglobin in RBCs precipitates causing the cells to sickle ie., the cells acquire a bent shape similar to a sickle, and some times cell bursts.
Normal Haemoglobin:
Val – His – Leu – Thr – Pro – Glu – Glu – Lys –
Sickle Cell Haemoglobin:
– Val – His – Leu – Thr – Pro – Val – Glu – Lys
The sickle cell haemoglobin contains valine (Val) in place of glutamic acid (Glu) present in normal haemoglobin.

1. Carbohydrates are the main source of energy for a living being.
2. Carbohydrates are the major constituent of the plant body.
3. Deoxyribose and ribose sugars are the constituents of genetic material i.e., DNA & RNA.
4. Starch is used as food. Cellulose acts as the source of shelter and clothing.