Test: Biomacromolecules (NCERT) - NEET MCQ

In polysaccharides, monosaccharides are linked together by glycosidic bond (C−O−C). It is formed by dehydration between two carbon atoms of two adjacent monosaccharides. Water has hydrogen bonding. Amino acids in a protein are linked through peptide bond whereas ester bond is present in fats.

Ans: 2
Sol: An alpha helix is a secondary structure of a protein because it involves the local coiling of the polypeptide chain into a helix, stabilized by hydrogen bonds between the backbone atoms. It is one of the common structural patterns found within proteins, distinct from the primary, tertiary, and quaternary structures.
4o

A deoxyriboncleotide of DNA is formed by cross-linking of three chemicals- deoxyribose sugar (C₅H₁₀O₄), a nitrogen base and phosphoric acid (H₃PO₄). The backbone of a DNA strand is built up of alternate deoxyribose and phosphoric acid grounds. The phosphate group is connected to carbon 5' of the sugar residue of its own nucleotide and cerbon 3' of the sugar residue of the next nucleotide by phosphodiester bonds.

Chitin is the second most abundant polysaccharide (after cellulose). Chitin is not a storage polysaccharide rather it is a structural homopolysaccharide which forms the structure component of fungal walls and exoskeleton of artropods. It is an unbranched polysaccharide formed of N- acetylglucosamine (NAG) monomers joined together by β−1,4 linkages.

Proteins are said to have quaternary structure if they consist of 2 or more polypeptide chains untied by force other than covalent bonds (i.e., not peptide are hydrogen bonds). The force that stabilise these aggregates are hydrogen bonds and electrostatic bonds formed between amino acids on the polypeptide chains. Haemoglobin, the oxygen-transporting protein of blood, is an example of quaternary structure. This protein consists of four peptide chains of two types-α and β chains that occur in pairs.

A. Cotton fibre is cellulose. The tainted form of cellulose is cotton and contains about 90% cellulose.

B. Exoskeleton of cockroach is Chitin. Chitin is the main component of the outer skeleton of the cockroaches and it is a fibrous material which consists of polysaccharides.  

C. Liver is glycogen which remains inside the body of animals in the form of stored energy.

D. Peeled potato is starch which is basically a sequence of units of glucose which is connected by glycosidic bonds.

E. Roots of Dahlia produces inulin, which can help the body deal with its own insulin needs. The Inulin molecules obtained from Dahlia tubers are called Dahlin. 

Correct option is B)

B-DNA is the most commonly found form of DNA in nature. This form of DNA is very narrow and elongated.
B-DNA contains 10 base pairs per turn and each turn is about 34 Å long.

The average composition of a living cell is water 70−90%, proteins 10−15%, nucleic acids 5−7%, carbohydrates 3%, lipids 2%, ions 1%.

Given figure represents a part of DNA molecules, in which phosphoric acid groups and deoxyribose sugars are linked together by means of phosphodiester bonds. The two DNA chains are antiparallel, i.e., they run parallel but in opposite directions. In one chain the direction is 5'→3' while in the opposite one it is 3'→5'. The chains are held together by hydrogen bonds between their bases. Adenine (A), a purine of one chain lies exactly opposite to thymine (T), a pyrimidine of the other chain . Similarly, cytosine (C), a primidine lies opposite to guanine (G) a purine. Three hydrogen bonds occur between cytosine and guanine (C≡G) at positions 1'−1',2'−6' and 6'−2'. There are two such hydrogen bonds between adenone and thymine (A=T) which are formed at positions 1'−3' and 6'−4'. Hydrogen bonds occur between hydrogen of one base and oxygen or nitrogen of the other base.

A polypeptide is formed by the condensation of glycine monomers, i.e., by the eliminetion of one water molecule during the formation of each peptide bond. When 10 glycine (C₂H₅O₂N), molecules participate, 9H₂O molecules are eliminated. Thus resulting polypeptide will prossess the molecular formula C₂₀H₃₂O₁₁N₁₀.

The term Lipid was coined by Bloor. Lipids are the esters of fatty acid and alcohol. These are hydrophobic that is these are insoluble in water but soluble in benzene, ether and chloroform. As these are insoluble in water when they are added with water they separate to form two layers.

Starch can hold I₂ (iodine) molecules in the helical portion. The starch-I₂ is blue in colour. Cellulose does not contain complex helices and hence cannot hold I₂ and hence remain colourless.

Glycogen is a branched polymer of glucose. Glucose residues are linked linearly by α-1, 4 glycosidic bonds (glycosidic bonds formed between C-1 of one glucose with the C-4 of the next). After every 10-14 units, a side chain branch occurs that attach at C-6 of a glucose unit by α-1, 6 glycosidic linkages.

Vinblastine is used as an anticancer drug whereas curcumin is a component of turmeric and also used as a drug.

Collagen is a protein which is most abundant in the animal world and is a connective tissue and rubisco is an enzyme which is the most abundant protein in the whole biosphere because rubisco is the enzyme which is responsible for the sugar formation during photosynthesis.

(i) The right end of the polysaccharide chain which has a free reactive end and is known as reducing and left side is the non-reducing end.
Starch is a polymer of glucose that is made up of two types of chains amylose and amylopectin.
(ii) Amylose is a straight polymer with 1-4 glycosidic linkages and amylopectin is a branched polymer with 1-6 glycosidic linkage.
(iii) Starch can hold iodine molecule in the amylopectin helical structure. Starch is the reserve food material in plants. Glycogen is also a storage food material in animals. It is also branched structure, a polymer of glucose which has linear 1-4 glycosidic bonds and branched 1-6 glycosidic linkage.
(iv) Cellulose is a linear polymer of Beta D glucose which does not trap iodine molecules.

(i) Endergonic reactions are the reactions which involve intake / absorption of energy. Exergonic reactions are the reactions which involve the release of energy. During ATP formation, energy is taken in and stored in the form of ATP; whereas energy is liberated during breakdown of ATP.
(ii) ADP + Pi + Energy ⇌ ATP reaction can occur in a cyclic manner of build up and break-down reactions.
(iii) ATP is called a high-energy molecule because it releases a large amount of usable energy when it loses its terminal phosphate group to become adenosine diphosphate (ADP).

(i) Carbohydrate, on the basis of the number of molecules present, is divided into monosaccharides, disaccharide and polysaccharides. Fructose is also known as the fruit sugar and is a monosaccharide. It is a 6 carbon molecule. Glycine is the simplest amino acid as it contains hydrogen in the side chain. (ii) Lactose is a disaccharide which means it has two molecules of same or different monosaccharide units. Lactose is also known as the milk sugar. 
(iii) On hydrolysis, lactose produces glucose and galactose.
(iv) Cellulose is a polysaccharide and an important constituent of cell wall it is made up of Beta D glucose units linked by 1-4 glycosidic linkage.

Homeostasis is the regulation by an organism of the chemical composition of its body fluids and other aspects of its internal environment so that physiological processes can proceed at optimum rates.

Adult human haemoglobin consists of 4 subunits. Two of these are identical to each other. Hence, two subunits of α type and two subunits of β type together constitute the human haemoglobin (Hb).