Chapter 9: Biomolecules Assertion-Reason Questions | biology Class 11 CBSE

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 1

Logic Check

Assertion (A): Carbon is more abundant in living organisms than in the earth's crust. Reason (R): Living organisms are made of unique elements not found in non-living matter.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 2

Logic Check

Assertion (A): The acid-soluble pool represents roughly the cytoplasmic composition of the cell. Reason (R): Macromolecules from the cytoplasm and organelles become the acid-insoluble fraction.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 3

Logic Check

Assertion (A): Lipids are classified as macromolecules because their molecular weight exceeds 10,000 daltons. Reason (R): Lipids are found in the acid-insoluble fraction because membrane-derived lipid vesicles are not water-soluble.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 4

Logic Check

Assertion (A): Primary metabolites have identifiable functions in normal physiological processes. Reason (R): Secondary metabolites like alkaloids and flavonoids are found in all animal cells.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 5

Logic Check

Assertion (A): Starch gives a blue-black colour with iodine. Reason (R): Starch forms helical secondary structures that can physically trap iodine molecules within the coils.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 6

Logic Check

Assertion (A): Cellulose does not give a blue colour with iodine. Reason (R): Cellulose does not contain complex helices and hence cannot hold iodine molecules.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 7

Logic Check

Assertion (A): Proteins are heteropolymers. Reason (R): Proteins are made of 20 different types of amino acids, so no single type of monomer repeats throughout the chain.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): The tertiary structure of a protein is absolutely necessary for its biological activity. Reason (R): The tertiary structure creates the active site — the crevice or pocket into which the substrate fits for catalysis.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 9

Logic Check

Assertion (A): DNA is called deoxyribonucleic acid because it contains deoxyribose sugar. Reason (R): RNA contains ribose sugar, while DNA contains 2'-deoxyribose, which differs by having one fewer hydroxyl group.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 10

Logic Check

Assertion (A): Enzymes lower the activation energy of a chemical reaction. Reason (R): Enzymes increase the overall energy of the substrate, pushing it to the transition state more quickly.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 11

Logic Check

Assertion (A): Ribozymes are proteins with catalytic activity. Reason (R): Almost all enzymes are proteins, but some nucleic acids also behave like enzymes.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 12

Logic Check

Assertion (A): Enzyme activity declines at temperatures both below and above the optimum temperature. Reason (R): Low temperature permanently denatures the enzyme while high temperature temporarily inactivates it.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 13

Logic Check

Assertion (A): Competitive inhibitors are used in the control of bacterial pathogens. Reason (R): Competitive inhibitors closely resemble the substrate and compete for the active site of the enzyme, reducing enzyme action.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 14

Logic Check

Assertion (A): Formation of the enzyme-substrate (ES) complex is essential for catalysis. Reason (R): The ES complex is a permanent structure that remains intact throughout the life of the enzyme.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): Collagen is the most abundant protein in the animal world. Reason (R): RuBisCO is the most abundant protein in the whole biosphere.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 16

Logic Check

Assertion (A): A nucleoside is formed when a nitrogenous base attaches to a pentose sugar. Reason (R): When a phosphate group is also esterified to the sugar of a nucleoside, the compound becomes a nucleotide.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): Prosthetic groups are tightly bound to the apoenzyme and form part of the active site. Reason (R): Haem is a prosthetic group in the enzyme catalase, which catalyses the breakdown of hydrogen peroxide.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 18

Logic Check

Assertion (A): Water is the most abundant chemical in living organisms. Reason (R): Water constitutes 70–90% of the total cellular mass of living organisms.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 19

Logic Check

Assertion (A): The same glycolytic pathway produces pyruvic acid under aerobic conditions in muscles. Reason (R): In yeast during fermentation, the same pathway leads to the production of lactic acid.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): Glycogen is a branched polysaccharide found in animal tissues. Reason (R): In a glycogen chain, the right end is called the reducing end and the left end is called the non-reducing end.

Reasoning Options

ByteNotes

Chapter sections

Chapter 9: Biomolecules | Assertion-Reason

Assertion (A): Carbon is more abundant in living organisms than in the earth's crust. Reason (R): Living organisms are made of unique elements not found in non-living matter.

Assertion (A): The acid-soluble pool represents roughly the cytoplasmic composition of the cell. Reason (R): Macromolecules from the cytoplasm and organelles become the acid-insoluble fraction.

Assertion (A): Lipids are classified as macromolecules because their molecular weight exceeds 10,000 daltons. Reason (R): Lipids are found in the acid-insoluble fraction because membrane-derived lipid vesicles are not water-soluble.

Assertion (A): Primary metabolites have identifiable functions in normal physiological processes. Reason (R): Secondary metabolites like alkaloids and flavonoids are found in all animal cells.

Assertion (A): Starch gives a blue-black colour with iodine. Reason (R): Starch forms helical secondary structures that can physically trap iodine molecules within the coils.

Assertion (A): Cellulose does not give a blue colour with iodine. Reason (R): Cellulose does not contain complex helices and hence cannot hold iodine molecules.

Assertion (A): Proteins are heteropolymers. Reason (R): Proteins are made of 20 different types of amino acids, so no single type of monomer repeats throughout the chain.

Assertion (A): The tertiary structure of a protein is absolutely necessary for its biological activity. Reason (R): The tertiary structure creates the active site — the crevice or pocket into which the substrate fits for catalysis.

Assertion (A): DNA is called deoxyribonucleic acid because it contains deoxyribose sugar. Reason (R): RNA contains ribose sugar, while DNA contains 2'-deoxyribose, which differs by having one fewer hydroxyl group.

Assertion (A): Enzymes lower the activation energy of a chemical reaction. Reason (R): Enzymes increase the overall energy of the substrate, pushing it to the transition state more quickly.

Assertion (A): Ribozymes are proteins with catalytic activity. Reason (R): Almost all enzymes are proteins, but some nucleic acids also behave like enzymes.

Assertion (A): Enzyme activity declines at temperatures both below and above the optimum temperature. Reason (R): Low temperature permanently denatures the enzyme while high temperature temporarily inactivates it.

Assertion (A): Competitive inhibitors are used in the control of bacterial pathogens. Reason (R): Competitive inhibitors closely resemble the substrate and compete for the active site of the enzyme, reducing enzyme action.

Assertion (A): Formation of the enzyme-substrate (ES) complex is essential for catalysis. Reason (R): The ES complex is a permanent structure that remains intact throughout the life of the enzyme.

Assertion (A): Collagen is the most abundant protein in the animal world. Reason (R): RuBisCO is the most abundant protein in the whole biosphere.

Assertion (A): A nucleoside is formed when a nitrogenous base attaches to a pentose sugar. Reason (R): When a phosphate group is also esterified to the sugar of a nucleoside, the compound becomes a nucleotide.

Assertion (A): Prosthetic groups are tightly bound to the apoenzyme and form part of the active site. Reason (R): Haem is a prosthetic group in the enzyme catalase, which catalyses the breakdown of hydrogen peroxide.

Assertion (A): Water is the most abundant chemical in living organisms. Reason (R): Water constitutes 70–90% of the total cellular mass of living organisms.

Assertion (A): The same glycolytic pathway produces pyruvic acid under aerobic conditions in muscles. Reason (R): In yeast during fermentation, the same pathway leads to the production of lactic acid.

Assertion (A): Glycogen is a branched polysaccharide found in animal tissues. Reason (R): In a glycogen chain, the right end is called the reducing end and the left end is called the non-reducing end.

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