NCERT solutions Science Textbook for Class 10 chapter 9 Heredity and Evolution



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Chapter 9 - Heredity and Evolution

Page 143

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Q 1 | Page 143 | view solution

 How does the creation of variations in a species promote survival?

Q 2 | Page 143 | view solution

Page 147

How do Mendel’s experiments show that the traits may be dominant or recessive 

Q 1 | Page 147 | view solution

How do Mendel's experiment show that traits are inherited independently?

Q 2 | Page 147 | view solution

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

Q 3 | Page 147 | view solution

 How is the sex of the child determined in human beings?

Q 4 | Page 147 | view solution

Page 150

What are the different ways in which individuals with a particular trait may increase in a population?

Q 1 | Page 150 | view solution

Why are traits acquired during the life-time of an individual not inherited?

Q 2 | Page 150 | view solution

Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

Q 3 | Page 150 | view solution

Page 151

What factors could lead to the rise of a new species?

Q 1 | Page 151 | view solution

Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not?

Q 2 | Page 151 | view solution

Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?

Q 3 | Page 151 | view solution

Page 156

Give an example of characteristics being used to determine how close two species are in evolutionary terms.

Q 1 | Page 156 | view solution

Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?

Q 2 | Page 156 | view solution

What are fossils? What do they tell us about the process of evolution?

Q 3 | Page 156 | view solution

Page 158

Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species?

Q 1 | Page 158 | view solution

In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?

Q 2 | Page 158 | view solution

Page 159

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw

Q 1 | Page 159 | view solution

 An example of homologous organs is

a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.

Q 2 | Page 159 | view solution

 In evolutionary terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.

Q 3 | Page 159 | view solution

A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Q 4 | Page 159 | view solution

How are the areas of study – evolution and classification – interlinked?

Q 5 | Page 159 | view solution

 Explain the terms analogous and homologous organs with examples.

Q 6 | Page 159 | view solution

Outline a project which aims to find the dominant coat colour in dogs.

Q 7 | Page 159 | view solution

Explain the importance of fossils in deciding evolutionary relationships.

Q 8 | Page 159 | view solution

 What evidence do we have for the origin of life from inanimate matter?

Q 9 | Page 159 | view solution

Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Q 10 | Page 159 | view solution

How is the equal genetic contribution of male and female parents ensured in the progeny?

Q 11 | Page 159 | view solution

Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

Q 12 | Page 159 | view solution

Extra questions

Explain sex determination in human beings.

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