Question

1. A curtain is hanging at the entrance of a room. A long corridor runs at right angles to the door
that is parallel to the curtain. If a strong wind blows along the corridor, then what will happen to
the curtain. Explain.
2. To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen
and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the
exhaust fan will expel the hot air more effectively? Explain why?
3. Why is it advisable not to shut all the doors and windows during a storm?
4. A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothes line in the
balcony. Towards which direction the clothes will be blown in the afternoon? Explain.
5. A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of
the day does this happen – at midnight or in the afternoon?
6. Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she
opened the refrigerator she found the bottle had collapsed. Explain the possible reason.
7. When strong/high speed wind blows, an umbrella held upright at times gets upturned. Explain
the reason.
8. Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away
during a fierce wind storm.
9. One morning as Paheli strolled in her garden she noticed many small plants which were not
there a week ago. She wondered where they had come from as nobody had planted them
there. Explain the reason for the growth of these plants.
10. When you keep food items like bread and fruits outside for a long time especially during the
rainy season, you will observe a cottony growth on them.
(a) What is this growth called?
(b) How does the growth take place?
11. Coconut is a large and heavy fruit. How is it adapted for dispersal by water?
12. In the figure of a flower given in Figure 12.4 of your book, label the parts whose functions are
given below and give their names.
(a) The part which contains pollen grains.
(b) The part where the female gamete is formed.
(c) The female reproductive part where pollen grains germinate.
(d) The colourful part of flower which attracts insects.
13.Explain different modes of asexual reproduction.
14.Explain the process of fertilisation in flowers.
15.State some differences between self and cross pollination.

Answer 1

• When the wind blows through the corridor, the curtain will be swayed through the door.

• Since the corridor walls are at right angles with the door, it will subtend an angle at the point where it is attached to the door and an arc.

• The curtain will form the curved surface of the subtended arc.