Class 10 Heredity And Evolution Exemplar




(Multiple Choice Questions):

Q-1: Exchange of genetic material takes place in

(a) vegetative reproduction                    (b) asexual reproduction

(c) sexual reproduction                            (d) budding

Solution: (c)

Exchange of genetic material takes place in sexual reproduction as genes of two parents are involved.

In asexual reproduction, no exchange of genetic material takes place as a single parent is involved.

Budding and vegetative reproduction are types of asexual reproduction. So there is no change of genetic material.

Q-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 fertilisation                           (b) self pollination

(c) cross fertilisation                              (d) no fertilisation

Solution: (c)

The nature of the cross will be cross fertilisation. Fertilising a plant using pollen from another plant of the same species is cross-fertilisation.

Double fertilisation is a complex fertilisation mechanism of flowering plants. It involves fusion of a male and female gamete. Self-pollination is a form of pollination that occur in a flower that has both stamen and carpel.

Q-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’

Solution: (a)

In  generation, the cross between TT and tt will result into all tall plants. Thus, tallness is the dominant trait.

Whenever two traits of a character are crossed, the F1 plants show only one of the traits. This trait is called the dominant trait. The other trait (dwarfness is this case) that does not express itself in F1 generation is called the recessive trait.

Q-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

Solution: (d)

The incorrect statement is (d) as fat molecules are not related to genes.

On the other hand, genes contain information for making proteins in a cell. The proteins synthesised may be enzymes that catalyse biochemical reactions. The enzymes also control the process of making hormones. This explain why a, b and c are correct.

Q-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

Solution: (a)

The cross between RRyy and rrYY seeds will produce RrYy (round and yellow) seeds in F1 generation, because round and yellow are dominant traits.

Q-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)

Solution: (c)

In human males, one pair called the sex chromosomes are unpaired. Here, one is a normal-sized X-chromosome while other is a short Y-chromosome. Women have a perfect pair of sex chromosome, both called X.

Q-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

Solution: (b)

The maleness of a child is determined by the Y-chromosome in zygote inherited from the father. If X-chromosome is inherited from the father, the zygote will develop into girl.

Q-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

Solution: (b)

A zygote that has an X-chromosome inherited from father will develop into a girl.

All children whether boys or girls inherit an X-chromosome from their mother.

Thus, sex is determined by what they inherit from their father. A child who inherits X-chromosome from her father will be a girl, and one who inherits a Y-chromosome from him will be a boy.

Q-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 generally controlled

(c) Low weight parents can have heavy weight progeny

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

Solution: (b)

The weight reduction due to starvation will not change the DNA of the germ cells, because low weight is not a trait that is genetically controlled or inherited. Thus, low weight parents may have weight progeny.

Traits which, are not inherited, i.e., the acquired traits are simply changes in rich-reproduction tissues, so, cannot be passed on to DNA of germ cells.

Evolution results from change in frequency of genes in a population over several generations.

Q-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)

Solution: (a)

New species may be formed if the DNA changes are severe enough, such as a change in the number of chromosome. This leads to new variations.

Q-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 F1 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)


The new combination in F1 progeny will be round yellow and wrinkled green.

The phenotypic ratio 9 : 3; 3 : 1 is obtained.

Round yellow : Round green : Wrinkled yellow : Wrinkled green = 9 : 3 ; 3 : 1

Q-12:A basked 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

Solution: (c)

Radish and carrot represent homologous structures as they have the same structure (or basic design) though they are different species.

Q-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) Winds of bird and wings of bat are homologous

Solution: (d)

Wings of birds and wings of bat are homologous. Since they have same basic design, however their origin is different.

Q-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

Solution: (b)

Fossils refer to the petrified remains of organism that lives in the past and get preserved in rocks. The fossil position in the layer of earth relates to the time of extinction of organisms.

If the fossil of an organism is found in the deeper layer of earth, then it is predicted that extinction of organism has occurred thousands of years ago. Whereas the fossils found closer to the surface are more recent.

Q-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

Solution: (a)

All variations in a species do not have equal chances of survival. Some of the variations may be so drastic that the new DNA copy cannot work with the cellular apparatus it inherits. Such a newborn cell dies soon.

Depending on the nature of variation, different individual will have different kinds of advantage. Variations results from change in genetic composition. Advantageous variations are selected by environmental factors. This leads to evolution and speciation. In asexual reproduction, there is minimum variation that is due to small errors in DNA copy.

Q-16: A trait in a 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

Solution: (c)

A trait of an organism is influenced by both maternal and paternal DNA. It is passed down from one generation to another through genes found on the chromosomes. During sexual reproduction, both mother and father pass their genes to their children, thus determining their traits, or characteristic features.

Q-17: Select the group which shares maximum number of common characters

(a) two individual of a species                 (b) two species of a genus

(c) two genes of a family                          (d) two genera of two families

Solution: (a)

Two individuals of a species share maximum number of common characters. A species is a population of organisms consisting of similar individuals which can breed together and produce fertile offspring.

Q-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

Solution: (b)

Accumulation of variations over several generations forms new species. Genetic drift accumulate different changes in sub-populations of a species. Also, natural selection may also operate differently in the different geographic locations. Eventually, different groups of new species will be formed.

Q-19: From the list given below, select the character which can be acquired but no inherited.

(a) colour of eye          (b) colour of skin              (c) size of body          (d) nature of hair

Solution: (c)

Acquired traits develop in response to the environment. The size of the body is an acquired trait because it can be change don the availability of less or more food. The other three colour of eye, and skin and nature of hair are inherited characters form the parents.

Q-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 chromosome

(c) sex chromosomes  (d) any chromosome

Solution: (a)

The two version of a trait are situated on copies of same chromosome. Each parent contributes one copy of the gene for a particular character. In the gamete however, only one copy is present due to reduction division. At the time of fusion, the diploid condition is maintained. Sex chromosomes carry genes for sexual characters.