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NCERT Exemplar Solution for CBSE Class 10 Science Chapter 9: Heredity and Evolution (Part-I)

May 29, 2017 12:45 IST

    Heredity and Evolution NCERT Exemplar Problems, Class 10 Science NCERT ExemplarHere you get the CBSE Class 10 Science chapter 9, Heredity and Evolution: NCERT Exemplar Problems and Solutions (Part-I). This part of the chapter includes solutions for Question No.1 to 25 from the NCERT Exemplar Problems for Class 10 Science Chapter: Heredity and Evolution. These questions include only the Multiple Choice Questions (MCQs) framed from various important topics in the chapter. Each question is provided with a detailed explanation.

    CBSE Class 10 Science Syllabus 2017-2018

    NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. All these questions are very important to prepare for CBSE Class 10 Science Board Examination 2017-2018 as well as other competitive exams.

    Find below the NCERT Exemplar problems and their solutions for Class 10 Science Chapter, Heredity and Evolution:

    Multiple Choice Questions (MCQs)

    Question. 1 Exchange of genetic material takes place in

    (a) Vegetative reproduction

    (b) Asexual reproduction

    (c) Sexual reproduction

    (d) Budding

    Answer. (c)

    Explanation:  Sexual reproduction involves meiosis in gamete mother cells to form gametes and fusion of male and female gametes into zygote.

    Question. 2 Two pink coloured flowers on crossing resulted in 1 red, 2 pink and 1 white flower progeny. The nature of the cross will be

    (a) Double fertilization

    (b) Self pollination

    (c) Cross fertilization

    (d) No fertilization

    Answer. (c)

    Explanation:  Cross fertilization is transfer of pollen from one plant to the stigma of flower borne on different plant of same species.

    Question. 3 A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because

    (a) Tallness is the dominant trait

    (b) Shortness is the dominant trait

    (c) Tallness is the recessive trait

    (d) Height of pea plant is not governed by gene 'T' or 't'

    Answer. (a)

    Explanation: According to law of dominance, a trait is represented by two contrasting factors of a gene in a heterozygous individual; the allele/factor that can express itself in heterozygous individual is called as dominant trait. The other factor whose effect is masked by presence of dominant factor, is called recessive factor.

    NCERT Solutions for CBSE Class 10 Science

    Question. 4 Which of the following statement is incorrect?

    (a) For every hormone there is a gene

    (b) For every protein there is a gene

    (c) For production of every enzyme there is a gene

    (d) For every molecule of fat there is a gene

    Answer. (d)

    Explanation:  Fat biosynthesis occurs through metabolic reaction.

    Question. 5 If a round, green seeded pea plant (RR yy) is crossed with wrinkled, yellow seeded pea plant, (rr YY) the seeds production in F1 generation are

    (a) Round and yellow

    (b) Round and green

    (c) Wrinkled and green

    (d) Wrinkled and yellow

    Answer. (a)

    Explanation:  The cross between RR yy and rr YY seeds will obtain RrYy offspring which will exhibit round and yellow phenotype as these traits are dominant one.

    Question. 6 In human males all, the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are

    (i) Large chromosome

    (ii) Small chromosome

    (iii) Y-chromosome

    (iv) X-chromosome

                (a) (i) and (ii)

                (b) (iii) only

                (c) (iii) and (iv)

                (d) (ii) and (iv)

    Answer. (c)

    Explanation:  Human males are hemizygous for X and Y chromosomes.

    Question. 7 The maleness of a child is determined by

    (a) The X-chromosome in the zygote

    (b) The Y-chromosome in zygote

    (c) The cytoplasm of germ cell which determines the sex

    (d) Sex is determined by chance

    Answer. (b)

    Explanation:  The maleness of a child is determined by presence of Y-chromosome in zygote.

    Question. 8 A zygote which has an X-chromosome inherited from the father will develop into a

    (a) Boy

    (b) Girl

    (c) X-chromosome does not determine the sex of a child

    (d) Either boy or girl

    Answer. (b)

    Explanation:  Humans follow XX- XY mechanism of sex determination.

    Question. 9 Select the incorrect statement

    (a) Frequency of certain genes in a population change over several generations resulting in evolution.

    (b) Reduction in weight of the organism due to starvation is genetically controlled.

    (c) Low weight parents can have heavy weight progeny.

    (d) Traits which are not inherited over generations do not cause evolution.

    Answer. (b)

    Explanation:  The weight reduction due to starvation is environmentally determined factor.

    Question. 10 New species may be formed if

    (i) DNA undergoes significant changes in germ cells.

    (ii) Chromosome number changes in the gamete.

    (iii) There is no change in the genetic material

    (iv) Mating does not take place

                (a) (I) and (ii)

                (b) (I) and (iii)

                (c) (ii), (iii) and (iv)

                (d) (i), (ii) and (iii)

    Answer. (a)

    Explanation:  Change in genetic material leads to reproductive isolation of population into a new species.

    Question. 11 Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce F1 progeny that have round, yellow (RrYy) seeds. When F1 plants are selfed, the F2 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)

    Answer. (b)

    Explanation:   The new combination in F2 progeny will be offspring showing phenotype other than aren’t ones (round and green; wrinkled yellow). Hence, the recombinant progeny will be one with round yellow and wrinkled green seeds.

    Question. 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

    Answer. (c)

    Explanation:  Homologous organs perform different functions and have different appearance but share common basic structural plan and origin.

    Question. 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 bird and wings of bat are homologous

    Answer. (d)

    Explanation:  Homologous organs perform different functions and have different appearance but share common basic structural plan and origin. Analogous organs perform similar function and have similar appearance but have different basic structure and origin.

    Question. 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

    Answer. (b)

    Explanation:  Depth of each stratum signifies the relative age of fossils present in it. The deeper the stratum, the older the rock and the fossils present in it.

    Question. 15 Which of the following statements is not true with respect to variation?

    (a) All variations in a species have equal chances 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.

    Answer. (a)

    Explanation:  Variations that impart reproductive or survival advantage to organisms are being favored during evolution.

    Question. 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

    Answer. (c)

    Explanation:  An organism develops from zygote which in turn is product of fusion of male and female gamete.

    Question. 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

    Answer. (a)

    Explanation:  Species form the lowest taxonomic category and includes all the organisms that share maximum number of common characters. While moving up in taxonomic hierarchy, number of shared characters get reduced.  

    Question. 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

    Answer. (b)

    Explanation: Accumulation of variations over several generations serve as raw material on which evolutionary force (natural selection) acts upon to create new species.

    Question. 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

    Answer. (c)

    Explanation: Environmentally determined traits are acquired. Size of body depends on nutritional status, health conditions etc.

    Question. 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

    Answer. (a)

    Explanation: The two versions of a trait are situated on homologous chromosomes.  

    Question. 21 Select the statements that describe characteristics of genes

    (i) Genes are specific sequence of bases in a DNA molecule

    (ii) A gene does not code for proteins

    (iii) In individuals of a given species, a specific gene is located on a particular chromosome

    (iv) Each chromosome has only one gene

                (a) (i) and (ii)

                (b) (i) and (iii)

                (c) (i) and (iv)

                (d) (iii) and (iv)

    Answer. (b)

    Explanation: Genes are stretches of DNA located on specific locus on a particular chromosome in individuals of a given species.

    Question. 22 In peas, a pure tall plant (TT) is crossed with a short plant (tt). The ratio of pure tall plants to short plants in F2 is

    (a) 1 : 3

    (b) 3 : 1

    (c) 1 : 1

    (d) 2:1

    Answer. (b)

    Explanation:  The monohybrid F2 generation phenotypic ratio is 3 : 1.

    Question. 23 The number of pair(s) of sex chromosomes in the zygote of humans is

    (a) One

    (b) Two

    (c) Three

    (d) Four

    Answer. (a)

    Explanation: Zygote is diploid structure and has one pair of sex chromosome (XX or XY).

    Question. 24 The theory of evolution of species by natural selection was given by

    (a) Mendel

    (b) Darwin

    (c) Morgan

    (d) Lamarck

    Answer. (b)

    Explanation: Darwin proposed the theory of natural selection to explain the process of evolution.

    Question. 25 Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution this means that

    (a) Reptiles have evolved from birds

    (b) There is no evolutionary connection between reptiles and birds

    (c) Feathers are homologous structures in both the organisms

    (d) Birds have evolved from reptiles

    Answer. (d)

    Explanation:  Development of flight feathers in reptilian ancestors of birds lead to evolution of birds (Aves).

    CBSE Class 10 NCERT Textbooks & NCERT Solutions

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