Chapter 10: Biomolecules Assertion-Reason Questions | chemistry Class 12 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): Sucrose is a non-reducing sugar. Reason (R): In sucrose, the anomeric carbons of both glucose and fructose are involved in the glycosidic bond, leaving no free aldehyde or ketone group.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 2

Logic Check

Assertion (A): Cellulose cannot be digested by human beings. Reason (R): Cellulose is composed of β-D-glucose units, and humans lack the enzyme to hydrolyse β-glycosidic bonds.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 3

Logic Check

Assertion (A): Denaturation of a protein destroys its primary structure. Reason (R): Denaturation involves the disruption of hydrogen bonds and disulphide linkages that maintain secondary and tertiary structures.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 4

Logic Check

Assertion (A): Glucose does not give Schiff's test despite containing an aldehydic group. Reason (R): Glucose predominantly exists in a cyclic hemiacetal form in which the free –CHO group is absent.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 5

Logic Check

Assertion (A): Amino acids behave like salts in aqueous solution. Reason (R): Amino acids exist as zwitter ions due to intramolecular proton transfer from the –COOH group to the –NH2 group.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 6

Logic Check

Assertion (A): Vitamin C must be taken regularly in the diet. Reason (R): Vitamin C is a water-soluble vitamin that is readily excreted in urine and cannot be stored in the body.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 7

Logic Check

Assertion (A): The α-helix structure of a protein is stabilised by hydrogen bonds. Reason (R): In α-helix, hydrogen bonds form between the –NH group of one amino acid and the –C=O group of the fourth amino acid residue in the chain.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): DNA is a double-stranded molecule while RNA is generally single-stranded. Reason (R): DNA contains thymine while RNA contains uracil in place of thymine.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 9

Logic Check

Assertion (A): Monosaccharides are classified as aldoses or ketoses. Reason (R): This classification is based on whether the monosaccharide contains an aldehydic group or a ketonic group.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 10

Logic Check

Assertion (A): Glycogen is also called 'animal starch'. Reason (R): Glycogen has the same structure as amylose and is the primary storage polysaccharide in plants.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 11

Logic Check

Assertion (A): All naturally occurring α-amino acids except glycine are optically active. Reason (R): The α-carbon atom in amino acids (except glycine) is asymmetric as it bears four different substituents.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 12

Logic Check

Assertion (A): Hydrolysis of lactose gives galactose and glucose. Reason (R): Lactose is a disaccharide in which β-D-galactose and β-D-glucose are linked by a C1–C4 glycosidic bond.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 13

Logic Check

Assertion (A): Enzymes are said to be highly specific. Reason (R): Enzymes are specific for a particular substrate and for a particular type of reaction due to the precise shape and chemistry of their active sites.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 14

Logic Check

Assertion (A): The 'D' prefix in D-glucose indicates that it is dextrorotatory. Reason (R): 'D' refers to the relative configuration of the molecule with respect to D-(+)-glyceraldehyde, not its optical rotation.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 15

Logic Check

Assertion (A): Starch is the main storage polysaccharide in plants. Reason (R): Starch is a polymer of α-D-glucose and consists of amylose and amylopectin components.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 16

Logic Check

Assertion (A): Proteins which have only α-amino acids are called simple proteins. Reason (R): Fibrous proteins are generally insoluble in water, while globular proteins are usually soluble in water.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): Nucleic acids are polynucleotides. Reason (R): Nucleotides are joined together by phosphodiester linkages between 5′ and 3′ carbon atoms of successive pentose sugars.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 18

Logic Check

Assertion (A): Fructose is a laevorotatory compound. Reason (R): Fructose belongs to the D-series and has the configuration comparable to D-(+)-glyceraldehyde at the lowest asymmetric carbon.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 19

Logic Check

Assertion (A): Vitamins A, D, E, and K are stored in the liver and adipose tissues. Reason (R): These vitamins are fat-soluble and are not excreted in urine.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): Hormones are produced by exocrine glands and transported through ducts. Reason (R): Insulin is a polypeptide hormone that regulates blood glucose levels.

Reasoning Options

ByteNotes

Chapter sections

Chapter 10: Biomolecules | Assertion-Reason

Assertion (A): Sucrose is a non-reducing sugar. Reason (R): In sucrose, the anomeric carbons of both glucose and fructose are involved in the glycosidic bond, leaving no free aldehyde or ketone group.

Assertion (A): Cellulose cannot be digested by human beings. Reason (R): Cellulose is composed of β-D-glucose units, and humans lack the enzyme to hydrolyse β-glycosidic bonds.

Assertion (A): Denaturation of a protein destroys its primary structure. Reason (R): Denaturation involves the disruption of hydrogen bonds and disulphide linkages that maintain secondary and tertiary structures.

Assertion (A): Glucose does not give Schiff's test despite containing an aldehydic group. Reason (R): Glucose predominantly exists in a cyclic hemiacetal form in which the free –CHO group is absent.

Assertion (A): Amino acids behave like salts in aqueous solution. Reason (R): Amino acids exist as zwitter ions due to intramolecular proton transfer from the –COOH group to the –NH2 group.

Assertion (A): Vitamin C must be taken regularly in the diet. Reason (R): Vitamin C is a water-soluble vitamin that is readily excreted in urine and cannot be stored in the body.

Assertion (A): The α-helix structure of a protein is stabilised by hydrogen bonds. Reason (R): In α-helix, hydrogen bonds form between the –NH group of one amino acid and the –C=O group of the fourth amino acid residue in the chain.

Assertion (A): DNA is a double-stranded molecule while RNA is generally single-stranded. Reason (R): DNA contains thymine while RNA contains uracil in place of thymine.

Assertion (A): Monosaccharides are classified as aldoses or ketoses. Reason (R): This classification is based on whether the monosaccharide contains an aldehydic group or a ketonic group.

Assertion (A): Glycogen is also called 'animal starch'. Reason (R): Glycogen has the same structure as amylose and is the primary storage polysaccharide in plants.

Assertion (A): All naturally occurring α-amino acids except glycine are optically active. Reason (R): The α-carbon atom in amino acids (except glycine) is asymmetric as it bears four different substituents.

Assertion (A): Hydrolysis of lactose gives galactose and glucose. Reason (R): Lactose is a disaccharide in which β-D-galactose and β-D-glucose are linked by a C1–C4 glycosidic bond.

Assertion (A): Enzymes are said to be highly specific. Reason (R): Enzymes are specific for a particular substrate and for a particular type of reaction due to the precise shape and chemistry of their active sites.

Assertion (A): The 'D' prefix in D-glucose indicates that it is dextrorotatory. Reason (R): 'D' refers to the relative configuration of the molecule with respect to D-(+)-glyceraldehyde, not its optical rotation.

Assertion (A): Starch is the main storage polysaccharide in plants. Reason (R): Starch is a polymer of α-D-glucose and consists of amylose and amylopectin components.

Assertion (A): Proteins which have only α-amino acids are called simple proteins. Reason (R): Fibrous proteins are generally insoluble in water, while globular proteins are usually soluble in water.

Assertion (A): Nucleic acids are polynucleotides. Reason (R): Nucleotides are joined together by phosphodiester linkages between 5′ and 3′ carbon atoms of successive pentose sugars.

Assertion (A): Fructose is a laevorotatory compound. Reason (R): Fructose belongs to the D-series and has the configuration comparable to D-(+)-glyceraldehyde at the lowest asymmetric carbon.

Assertion (A): Vitamins A, D, E, and K are stored in the liver and adipose tissues. Reason (R): These vitamins are fat-soluble and are not excreted in urine.

Assertion (A): Hormones are produced by exocrine glands and transported through ducts. Reason (R): Insulin is a polypeptide hormone that regulates blood glucose levels.

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