Revision 2

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91. Why spores are usually covered by a hard protective coat? 
1. Why spores are usually covered by a hard protective coat?
2. What is meant by sexual reproduction?
3. What is meant by a unisexual flower?
4. What is meant by syngamy?
5. Define: (a) Speed (b) Time.
6. What is a simple pendulum?
7. When would we say an object is in motion?
8. The distance between two stations is 200 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
9. Show the shape of the distance–time graph for the motion in the following cases:
   (a) A car moving with a constant speed.
   (b) A car parked on a side road.
10. What is a circuit diagram?
11. What is heating effect of electric current?
12. What is magnetic effect of an electric current?
13. Give four applications of an electromagnet.
14. Draw the symbols to represent the following components of electrical circuits: Connecting wires, Switch in the ‘OFF’ position, Bulb, Cell, Switch in the ‘ON’ position, and Battery.
15. What is meant by:
    (a) Regular reflection
    (b) Lateral inversion
16. What is reflection of light? What type of reflection produces images?
17. What are real and virtual images?
18. State the laws of reflection. Draw a diagram to show incident and reflected rays.
19. List some characteristics of a plane mirror.
20. Define the following terms:
    (c) Soil erosion
    (d) Deforestation
21. What are decomposers? Name any two of them. What do they do in the forest?
22. How do forests help in preventing floods? Explain.
23. What is the role of forests in maintaining the balance between oxygen and carbon dioxide in the atmosphere? Explain.
24. Name any four water-borne diseases which are caused by drinking contaminated water.
25. What role you can play as an active citizen in relation to sanitation?