Page 87 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

5. Smoking damages .................. .

Ans. lungs

6. Plants respire throughout the .................. and .................. .
Ans. day and night

7. Cockroaches have tiny holes on the sides of their body called ............... .

Ans. spiracles
C. State whether the following statements are true (T) or false (F).

1. While exercising, the breathing rate slows down.

2. The size of chest cavity increases during inhalation.
3. Gills in fishes are well supplied with blood vessels for exchange of gases.

4. Stomata are the tiny pores present on the leaves.

5. Respiration is a physical process.
6. Anaerobic respiration takes place in the cells in the absence or lack of oxygen.

7. The tiny hair in the nasal cavity filter out dust and other particles present in the air.

8. We must not breathe through our nose.
Ans. 1. (F) 2. (T) 3. (T) 4. (T) 5. (F) 6. (T) 7. (T) 8. (F)

D. Give reasons.

1. The amount of nitrogen gas remains same in inhaled and exhaled air.

Ans. The amount of nitrogen gas remains same in inhaled and exhaled air because nitrogen
is neither used nor released in the process of respiration.

2. Fishes die when they are taken out of water.

Ans. Fish die out of water because their gills collapse and can’t extract oxygen from the
air. They dehydrate quickly, struggle to regulate their body temperature & die.

3. We should not over water a plant.

Ans. If we overwater the plants, the spaces between the soil particles get clogged. As a

result, the roots are not able to get enough air to respire and the plants can die due
to lack of oxygen. This in turn will kill the entire plant.

4. Mountaineers carry oxygen cylinders with them.

Ans. As we go to higher altitudes, the pressure of air in the atmosphere gradually starts
decreasing. This reduces the amount of oxygen available to our lungs while breathing,

this may cause dizziness and may also result in a condition called hypoxia (low oxygen

levels in the blood). Therefore, mountaineers often carry oxygen cylinders with them
for sufficient supply of oxygen at higher altitudes.

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