NIOS Class 10 Science & Technology Chapter 20 Solution

NIOS Class 10 Science & Technology Chapter 20 Solution – History Of Life On Earth

NIOS Class 10 Science & Technology Solution Chapter 20 History Of Life On Earth. NIOS Class 10 Science & Technology Chapter 20 Question Answers Download PDF. NIOS Class 10 Science Notes.

NIOS Class 10 Science & Technology Chapter 20 Solution

Board NIOS
Class 10th (Secondary)
Subject Science and Technology (220)
Topic Question Answer, Solution, Notes


CHAPTER: – 20.





1)When did the earth come into existence?

Ans: –4 to 5 million years age earth come into existence.


2)Why did life not exist on primitive earth?

Ans: – Because of the harsh climatic condition.


3)What are fossils?

Ans: – Remaining of the body parts of the animal and plant dumping under earth through million of years.


4)What is meant by Cambrain explosion?

Ans: –   600 million years ago sudden formation of different groups of invertebrates on the earth took place is known as Cambrain explosion.


5) From the geological time scale, find out the time in million years ago(mya) when:

(i) dinosaurs became extinct ____144 –65 mya________

(ii) human evolution began ____1.5 to 2 million years ago. __________

(iii) flowering plants became dominant on earth _______57 to 34 mya. _______.




1) Who is Charles Darwin? Name his famous book on natural selection.

Ans: – Charles Darwin tells the theory of natural selection.


2) Mention his two major contributions.

Ans: – His major contribution is –

(i) organisms through ancestry

(ii) Theory of Natural Selection


3) What is the function of Natural Selection?

Ans: – Which species made itself survivable then it remains otherwise not in this changing condition.


4) What is meant by Neo Darwinism?

Ans: –  The new Darwinism is light of progress in genetics.


5) Name the evolutionary mechanism that causes organisms to evolve.

Ans: – Through natural selection the evolution mechanism that cause organisms to evolve.



1) When did human evolution begin?

Ans: – About 1.5 to 2 million years ago human evolution begin.


2)Who is ‘Lucy’?

Ans: – Australopithecus is lucy.


3)Write the scientific name of Cro-magnon and Neanderthal man.

Ans: – The scientific name of co magnon is Homo sapiens


4)With which group of animals do humans share their immediate ancestors.

Ans: – The human shares their immediate ancestors with the apes.


5)Name the earliest ancestors of modern-day humans.

Ans: –Australopithecus is the earliest ancestors of modern day.



1)What were the primitive conditions on earth. Tell your friend/cousin/colleague. Then ask your friend to name the gas which was absent without which today no life can exist.

Ans: – This earth is created about a million years ago. When this earth created then the condition was not as today’s situation. Years after years the temperature changes to this and make an environment of living today ecosystem.


2)What are the main points of Oparins’ theory of Origin of life? Make a five-point quiz on it.

Ans: – The main point in the theory of origin of life is the starting period of life or the condition where the life is created and develop.


3)Mention Darwin’s two major contributions to evolutionary ideas.

Ans: –   Darwin major contribution is –

(i) organisms through ancestry

(ii) Theory of Natural Selection.


4)Write a note on Neo-Darwinism.

Ans: – The new Darwinism is light of progress in genetics. Which clearly tells us that the about the time going on the new things would be accepted and goes on.


5) List the five major events during geological time period beginning from origin of life. You may begin with origin of animals.

Ans: – 4600 mya: – planet form, 4500mya: – earth core and crust form, 4400 mya: – earth first ocean form, 3850 mya: – earth first life came, 1500mya: – oxygen came.


6)State major trends and stages of human evolution. Do you think humans are still evolving? Write five sentences to justify your response.

Ans: – The evolution is not struck it changing its pattern and this change we will see in future something about years after. In this way the new characteristics would be gain and goes on developing.


7) Earlier groups of animals became extinct due to natural happenings. Today, how is it that wild animals have become endangered and are heading towards extinction.

Ans: – Darwin in his theory tells us that which will capable of developing itself will go further otherwise will be extinct near future so some of animal doesn’t make themselves survived.


8)Write a ten sentences conversation between your father and yourself justifying the need for conservation of animals living in our forest.

Ans: – As the day by day the nature of the earth is changing so in near future if we don’t take any necessary steps then it will be harmful for our ecosystem as all are bonded in a chain.

Updated: February 25, 2022 — 11:24 am

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