NCERT Class X Science Class: Chapter –9. Heredity and Evolution – Part-2

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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

Image the Y-chromosome and X-chromosome

Image the Y-Chromosome and X-Chromosome

Image the Y-chromosome and X-chromosome

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

X and Y chromosome in zygote

X and Y Chromosome in Zygote

X and 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

Image prents/ daughters sons

Image Prents/ Daughters Sons

Image prents/ daughters sons

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

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