NCERT Class X Science Class: Chapter –9. Heredity and Evolution – Part-5

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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) (ii) and (iv)

Answer: B

Image the characteristics of genes

Image the Characteristics of Genes

Image the characteristics of genes

Question 22:

In peas, a pure tall plant is crossed with a short plant The ratio of pure tall plants to short plants in is

(a)

(b)

(c)

(d)

Answer: C

Cross between pure tall plant and a short plant

Cross between Pure Tall Plant and a Short Plant

Cross between pure tall plant and a short plant

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

Image sex determination in human being

Image Sex Determination in Human Being

Image sex determination in human being

Question 24:

The theory of evolution of species by natural selection was given by

(a) Mendel

(b) Darwin

(c) Morgan

(d) Lamarck

Answer: B

Image Darwin's theory of evolution

Image Darwin's Theory of Evolution

Image Darwin's theory 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

Image evolution of birds from reptiles

Image Evolution of Birds from Reptiles

Image evolution of birds from reptiles