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Glucose (C6H12O6) is a monosaccharide that serves as a monomer in the synthesis of numerous polysaccharides such as cellulose, starch, and others. As it has six carbons and an aldehyde group, it is known as an aldohexose. It exists naturally in both free and mixed forms and is the most significant energy source for all creatures. Hydrolysis is used in the industrial production of glucose from starch. Glucose can also be referred to as dextrose or D(+) glucose. Glucose has two cyclic isomeric forms (pyranose structure) known as anomers: -D(+)-Glucopyranose and -D(+)-Glucopyranose.
Q.1. Glycogen is a branched chain polymer of -D-glucose units, with the chain produced by C1—C4 glycosidic linkage and the branching formed by C1-C6 glycosidic linkage. The structure of glycogen is comparable to that of _____________________ .
(A) Amylose
(B) Amylopectin
(C) Cellulose
(D) Glucose
Answer: (B) Amylopectin
Explanation: Polysaccharides are composed of several monosaccharide units linked together by glycosidic bonds. These are the most frequent carbohydrates found in nature. Amylopectin is insoluble in water and accounts for around 80-85 percent of starch. It is a branched chain polymer of alpha-D-glucose units with C1-C4 glycosidic linkage forming the chain and C1-C6 glycosidic linkage forming the branching.
Q.2 Which of the following polymers is kept in animal livers?
(A) Amylose
(B) Cellulose
(C) Amylopectin
(D) Glycogen
Answer: (D) Glycogen
Explanation: Carbohydrates are stored as glycogen in the animal body. It is also known as animal starch due to its structure, which is similar to amylopectin but more strongly branched. It can be found in the liver muscle and brain.
Q.3. Sucrose (cane sugar) is a disaccharide. One molecule of sucrose on hydrolysis gives
(A) 2 molecules of glucose
(B) 2 molecules of glucose + 1 molecule of fructose
(C) 1 molecule of glucose + 1 molecule of fructose
(D) 2 molecules of fructose
Answer
iii) one molecule of glucose + one molecule of fructose
Sucrose is a common disaccharide that, when hydrolyzed, yields an equimolar combination of D-(+)-glucose and D-(-) fructose.
C12H22O11 (Sucrose) + H2O C6H12O6 (D-(+)-glucose) C6H12O6(D-(-) fructose)
Q.4. Proteins are found to have two different types of secondary structures viz. α-helix and β-pleated sheet structure. α-helix structure of protein is stabilised by which of the following bonds:
(A) Peptide bonds
(B) van der Waals forces
(C) Hydrogen bonds
(D) Dipole-dipole interactions
Answer: (C) Hydrogen bonds
Explanation: -helix and -pleated sheet structures: These structures form as a result of the regular folding of the polypeptide chain’s backbone due to hydrogen bonding between the peptide bond’s >C—O and —NH— groups.
The -NH group of each amino acid residue is hydrogen bound to the >C=O of an adjacent turn of the helix in one of the most typical ways in which a polypeptide chain makes all available hydrogen bonds by twisting into a right-handed screw (helix)
Q.5. Which of the following acids is a vitamin?
(A) Aspartic acid
(B) Ascorbic acid
(C) Adipic acid
(D) Saccharic acid
Answer: (B) Ascorbic acid
Explanation: Ascorbic acid is also another name for vitamin C.
Q.6. A dinucleotide is created by connecting two nucleotides together with phosphodiester. Which carbon atoms in pentose sugars and nucleotides are linked by these bonds?
(A) 5′ and 3′
(B) 1′ and 5′
(C) 5′ and 5′
(D) 3′ and 3′
Answer: (A) 5′ and 3′
Explanation: Nucleotides are linked together by a phosphodiester bond between the pentose sugar’s 5′ and 3′ carbon atoms.
Q.7. Nucleic acids are the polymers of
(A) Nucleosides
(B) Nucleotides
(C) Bases
(D) Sugars
Answer: (B) Nucleotides
Explanation: Because nucleic acids are long chain polymers of nucleotides, they are also known as polynucleotides
Q.8. Which of the given statements is not true about glucose?
(A) It is an aldohexose.
(B) On heating with HI it takes shape as n-hexane.
(C) It is present in furanose form.
(D) It does not give a 2,4-DNP test.
Answer: (iii)
Explanation: Fructose is present in furanose form.
Q.9 Each polypeptide in a protein contains amino acids that are connected in a precise sequence. This sequence of amino acid is known as
(A) primary structure of proteins.
(B) secondary structure of proteins.
(C) tertiary structure of proteins.
(D) quaternary structure of proteins.
Answer: (A) primary structure of proteins.
Explanation: Sequence of amino acids is said to be the primary structure of proteins.
Q.10. DNA and RNA contain four bases each. Which of the following bases is not present in RNA?
(A) Adenine
(B) Uracil
(C) Thymine
(D) Cytosine
Answer: (C) Thymine
Explanation: DNA is made up of four bases: adenine (A), guanine (G), cytosine (C), and thymine (T) (T). RNA has four nucleotides; the first three are the same as in DNA, but the fourth is uracil (U)
Q.11 Which of the following glucose reactions may be explained only by its cyclic structure?
(A) Glucose reacts to generate pentaacetate.
(B) Glucose forms an oxime when it combines with hydroxylamine.
(C) Glucose pentaacetate does not react with hydroxylamine.
(D) Nitric acid oxidizes glucose to gluconic acid.
Answer: (C) Pentaacetate of glucose does not react with hydroxylamine.
Explanation: The absence of a free —CHO group is indicated by the fact that glucose pentaacetate does not react with hydroxylamine
Q12. In the process of glycolysis
(A) glucose is converted to haem
(B) glucose is oxidized to pyruvate
(C) pyruvate is converted to citrate
(D) glucose is oxidized to glutamate
Answer: (B)
Q13. The two hemiacetal isomers of glucose, 𝛼-D-glucose and 𝛽-D-glucose are
(A) diastereomers
(B) epimers
(C) enantiomers
(D) anomers
Answer: (D)
