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NCERT Exemplar · Class 10 Science Heredity and Evolution

47 questions · 47 still being checked

Multiple Choice Questions 11–20 (part 2 of 5)

  1. Exercise 11

    Two pea plants one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce F1\displaystyle \mathrm{F}_1 progeny that have round, yellow (RrYy) seeds. When F1\displaystyle \mathrm{F}_1 plants are selfed, the F2\displaystyle \mathrm{F}_2 progeny will have new combination of characters. Choose the new combination from the following
    (i)
    Round, yellow
    (ii)
    Round, green
    (iii)
    Wrinkled, yellow
    (iv)
    Wrinkled, green
    (a) (i) and (ii)
    (b) (i) and (iv)
    (c) (ii) and (iii)
    (d) (i) and (iii)

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    NCERT’s answer
    (b)
    (b) (i) and (iv) \[RrYy \times RrYy \rightarrow 9\,\text{round yellow} : 3\,\text{round green} : 3\,\text{wrinkled yellow} : 1\,\text{wrinkled green} \] Parents were round-green and wrinkled-yellow; round-yellow and wrinkled-green are the new (recombinant) classes.

  2. Exercise 12

    A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures?
    (a)
    Carrot and potato
    (b)
    Carrot and tomato
    (c)
    Radish and carrot
    (d)
    Radish and potato

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    NCERT’s answer
    (c)
    (c) Radish and carrot Both are modified tap roots — same organ, same origin — so they are homologous; potato is a modified stem and tomato is a fruit.

  3. Exercise 13

    Select the correct statement
    (a)
    Tendril of a pea plant and phylloclade of Opuntia are homologous
    (b)
    Tendril of a pea plant and phylloclade of Opuntia are analogous
    (c)
    Wings of birds and limbs of lizards are analogous
    (d)
    Wings of birds and wings of bat are homologous
    NCERT’s answer
    (a)

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  4. Exercise 14

    If the fossil of an organism is found in the deeper layers of earth, then we can predict that
    (a)
    the extinction of organism has occurred recently
    (b)
    the extinction of organism has occurred thousands of years ago
    (c)
    the fossil position in the layers of earth is not related to its time of extinction
    (d)
    time of extinction cannot be determined

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    NCERT’s answer
    (b)
    (b) extinction occurred long ago By the law of superposition, deeper rock layers are older; a fossil buried deeper was laid down — and its organism became extinct — thousands of years further back in time.

  5. Exercise 15

    Which of the following statements is not true with respect to variation?
    (a)
    All variations in a species have equal chance of survival
    (b)
    Change in genetic composition results in variation
    (c)
    Selection of variants by environmental factors forms the basis of evolutionary processes.
    (d)
    Variation is minimum in asexual reproduction

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    NCERT’s answer
    (a)
    (a) All variations do not survive equally.Environmental selection favours better-adapted variants over others, so survival chances differ; genetic change, environmental selection and low variation in clones (b–d) are all correct.Answer: (a)

  6. Exercise 16

    A trait in an organism is influenced by
    (a)
    paternal DNA only
    (b)
    maternal DNA only
    (c)
    both maternal and paternal DNA
    (d)
    neither by paternal nor by maternal DNA

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    NCERT’s answer
    (c)
    (c) Both maternal and paternal DNA.Each parent's gamete contributes one allele of a gene; the trait results from both copies acting together, never from a single parent's DNA alone.Answer: (c)

  7. Exercise 17

    Select the group which shares maximum number of common characters
    (a)
    two individuals of a species
    (b)
    two species of a genus
    (c)
    two genera of a family
    (d)
    two genera of two families

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    NCERT’s answer
    (a)
    (a) Two individuals of a species.Species is the most specific taxonomic rank, so its members share the most characters; similarity drops as the group widens to genus, then family.Answer: (a)

  8. Exercise 18

    According to the evolutionary theory, formation of a new species is generally due to
    (a)
    sudden creation by nature
    (b)
    accumulation of variations over several generations
    (c)
    clones formed during asexual reproduction
    (d)
    movement of individuals from one habitat to another

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    NCERT’s answer
    (b)
    (b) Accumulation of variations over generations.Variations arising each generation build up, and natural selection acting on them over time diverges a population into a new species; sudden creation, clones and mere migration do not.Answer: (b)

  9. Exercise 19

    From the list given below, select the character which can be acquired but not inherited
    (a)
    colour of eye
    (b)
    colour of skin
    (c)
    size of body
    (d)
    nature of hair

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    NCERT’s answer
    (c)
    (c) Size of body.A body-size change gained through diet or exercise occurs in somatic (body) cells, not in germ cells:\[\text{diet, exercise}\Rightarrow\text{somatic cells changed},\ \text{germ-cell DNA unchanged}\Rightarrow\text{not passed on}\]The other options are inherited characters.

  10. Exercise 20

    The two versions of a trait (character) which are brought in by the male and female gametes are situated on
    (a)
    copies of the same chromosome
    (b)
    two different chromosomes
    (c)
    sex chromosomes
    (d)
    any chromosome

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    NCERT’s answer
    (a)
    (a) Copies of the same chromosome.Both versions sit at the same locus on a homologous pair, one chromosome from each parent. The pair may be autosomes or XX, so (c) is too narrow.