Chapter 6: Evolution Assertion-Reason Questions | biology Class 12 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): Miller's experiment provided evidence for chemical evolution. Reason (R): Miller obtained amino acids by passing electric discharge through a mixture of CH4, H2, NH3, and water vapour simulating early Earth conditions.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 2

Logic Check

Assertion (A): Louis Pasteur's experiment disproved the theory of biogenesis. Reason (R): Pasteur showed that sterilised broth in sealed flasks did not develop life, proving life comes only from pre-existing life.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 3

Logic Check

Assertion (A): Homologous structures are evidence for divergent evolution from a common ancestor. Reason (R): Homologous structures perform similar functions in all the organisms that possess them.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 4

Logic Check

Assertion (A): Analogous structures are evidence for convergent evolution. Reason (R): Analogous structures always have the same anatomical origin but perform different functions.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 5

Logic Check

Assertion (A): Hardy-Weinberg equilibrium is maintained in all natural populations. Reason (R): Natural populations are always large, have random mating, and are free from mutation, gene flow, and selection.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 6

Logic Check

Assertion (A): Darwin's finches on the Galápagos Islands are a classic example of adaptive radiation. Reason (R): Darwin observed finches during his voyage on the H.M.S. Beagle, which travelled around the world.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 7

Logic Check

Assertion (A): After industrialisation in England, dark-winged moths increased in frequency in polluted areas. Reason (R): Dark-winged moths were better camouflaged against soot-darkened tree trunks and were therefore less predated.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): Lamarck's theory of inheritance of acquired characters is accepted in modern evolutionary biology. Reason (R): Characters acquired by an organism during its lifetime are encoded in its DNA and passed to offspring.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): Genetic drift has a greater effect in large populations than in small populations. Reason (R): In small populations, random events can significantly alter allele frequencies, while in large populations, chance events average out.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 10

Logic Check

Assertion (A): The founder effect is a special case of genetic drift. Reason (R): Genetic drift is more pronounced in large populations than in small populations.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 11

Logic Check

Assertion (A): Fossils found in deeper rock strata are generally older than those found in shallower strata. Reason (R): Sedimentary rock layers are deposited over time, with older sediments accumulating at the bottom and newer sediments on top.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 12

Logic Check

Assertion (A): Hugo de Vries believed evolution is gradual, driven by small heritable variations. Reason (R): De Vries proposed the concept of mutations — large sudden changes — as the mechanism of evolution (saltation).

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 13

Logic Check

Assertion (A): Biochemical similarities in proteins across diverse organisms provide evidence for common ancestry. Reason (R): All organisms use ATP as a universal energy currency.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 14

Logic Check

Assertion (A): Embryos of all vertebrates including humans develop gill slits during early embryonic development. Reason (R): Gill slits are functional respiratory organs in the adult stages of all vertebrates.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): Evolution is a stochastic process. Reason (R): Evolution is based on chance events in nature and chance mutations in organisms, rather than a pre-determined or directed outcome.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 16

Logic Check

Assertion (A): The first non-cellular forms of life originated about 3 billion years ago. Reason (R): These early life forms were giant macromolecules such as RNA, proteins, and polysaccharides.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): Natural selection always leads to directional change in a population. Reason (R): Natural selection can lead to stabilising, directional, or disruptive change depending on environmental conditions.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 18

Logic Check

Assertion (A): Antibiotic resistance in bacteria is an example of evolution by anthropogenic action. Reason (R): Bacteria can reproduce to produce millions of individuals within hours due to their short life spans.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 19

Logic Check

Assertion (A): Australian marsupials and placental mammals represent a case of convergent evolution. Reason (R): Australian marsupials survived because they were geographically isolated from placental mammals.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 20

Logic Check

Assertion (A): Homo sapiens first arose in Africa and then migrated to other continents. Reason (R): Fossil evidence and genetic studies support the African origin of modern humans, who then spread across the world.

Reasoning Options

ByteNotes

Chapter sections

Chapter 6: Evolution | Assertion-Reason

Assertion (A): Miller's experiment provided evidence for chemical evolution. Reason (R): Miller obtained amino acids by passing electric discharge through a mixture of CH4, H2, NH3, and water vapour simulating early Earth conditions.

Assertion (A): Louis Pasteur's experiment disproved the theory of biogenesis. Reason (R): Pasteur showed that sterilised broth in sealed flasks did not develop life, proving life comes only from pre-existing life.

Assertion (A): Homologous structures are evidence for divergent evolution from a common ancestor. Reason (R): Homologous structures perform similar functions in all the organisms that possess them.

Assertion (A): Analogous structures are evidence for convergent evolution. Reason (R): Analogous structures always have the same anatomical origin but perform different functions.

Assertion (A): Hardy-Weinberg equilibrium is maintained in all natural populations. Reason (R): Natural populations are always large, have random mating, and are free from mutation, gene flow, and selection.

Assertion (A): Darwin's finches on the Galápagos Islands are a classic example of adaptive radiation. Reason (R): Darwin observed finches during his voyage on the H.M.S. Beagle, which travelled around the world.

Assertion (A): After industrialisation in England, dark-winged moths increased in frequency in polluted areas. Reason (R): Dark-winged moths were better camouflaged against soot-darkened tree trunks and were therefore less predated.

Assertion (A): Lamarck's theory of inheritance of acquired characters is accepted in modern evolutionary biology. Reason (R): Characters acquired by an organism during its lifetime are encoded in its DNA and passed to offspring.

Assertion (A): Genetic drift has a greater effect in large populations than in small populations. Reason (R): In small populations, random events can significantly alter allele frequencies, while in large populations, chance events average out.

Assertion (A): The founder effect is a special case of genetic drift. Reason (R): Genetic drift is more pronounced in large populations than in small populations.

Assertion (A): Fossils found in deeper rock strata are generally older than those found in shallower strata. Reason (R): Sedimentary rock layers are deposited over time, with older sediments accumulating at the bottom and newer sediments on top.

Assertion (A): Hugo de Vries believed evolution is gradual, driven by small heritable variations. Reason (R): De Vries proposed the concept of mutations — large sudden changes — as the mechanism of evolution (saltation).

Assertion (A): Biochemical similarities in proteins across diverse organisms provide evidence for common ancestry. Reason (R): All organisms use ATP as a universal energy currency.

Assertion (A): Embryos of all vertebrates including humans develop gill slits during early embryonic development. Reason (R): Gill slits are functional respiratory organs in the adult stages of all vertebrates.

Assertion (A): Evolution is a stochastic process. Reason (R): Evolution is based on chance events in nature and chance mutations in organisms, rather than a pre-determined or directed outcome.

Assertion (A): The first non-cellular forms of life originated about 3 billion years ago. Reason (R): These early life forms were giant macromolecules such as RNA, proteins, and polysaccharides.

Assertion (A): Natural selection always leads to directional change in a population. Reason (R): Natural selection can lead to stabilising, directional, or disruptive change depending on environmental conditions.

Assertion (A): Antibiotic resistance in bacteria is an example of evolution by anthropogenic action. Reason (R): Bacteria can reproduce to produce millions of individuals within hours due to their short life spans.

Assertion (A): Australian marsupials and placental mammals represent a case of convergent evolution. Reason (R): Australian marsupials survived because they were geographically isolated from placental mammals.

Assertion (A): Homo sapiens first arose in Africa and then migrated to other continents. Reason (R): Fossil evidence and genetic studies support the African origin of modern humans, who then spread across the world.

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