CBSE Guess > Papers > Question Papers > Class X > 2008 >Science > Science Theory

Q. 20. State two reasons each of conserving (a) forest and (b) wild life.

Ans. See Q.3, Textbook Questions, Chapter 16. [Page 175

Q. 21. Study the following diagram :

Name the parts labelled ‘A’ and ‘B’ and state one function of each.

Ans. A → Stomatal pore Function :
• Massive amounts of gaseous exchange takes place in the leaves through these pores for the purpose of photosynthesis.
B → Guard Cell
• The opening and closing of the stomatal pore is a function of the guard cells.

Q. 22. Why should we conserve forests? Suggest any two ways to conserve forests.

Ans. Forests are biodiverse hot spots. The main aim of conservation of forests is to try and preserve the biodiversity we have inherited. Loss of diversity may lead to loss of ecological stability. Two ways to conserve forests
(i) By silviculture. It means reforesting those forest lands from where large number of trees have been cut in a planned way.
(ii) By taking the help of the local people in conserving the forests.

Q. 23. What are fossils? What do they tell about the process of evolution?

Ans. See Q.6, Textbook Questions, Chapter 9. [Page 98

Q. 24. List four changes you would incorporate in your life-style in a move towards sustainable use of available resources.

Ans. Four changes I would like to incorporate in my life-style in a move towards a sustainable use of available resources –
(i) I will reduce the use of petrol by walking or cycling for short distances.
(ii) I will reduce the wastage of electricity by switching off unnecessary lights and fans.
(iii) I will send the discarded items of paper, plastic, glass and metal to the respective industries for making fresh paper, plastic, glass and metal objects.
(iv) I will ensure a continuous use of books by passing them on to my juniors.

Q. 25. Illustrate the following with the help of suitable diagrams :
(i) Binary Fission in Amoeba
(ii) Leaf of Bryophyllum with buds

Ans. (i) Binary Fission of Amoeba : See Q.1 (S.A.T.), Chapter 8. [Page 85
(ii) Leaf of Bryophyllum : See Q.2 (v) (L.A.T.), Chapter 8. [Page 90

Science 2008 Question Papers Class X
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