Breathing – (Activity 10.2)
1) Close your nostril and mouth tightly and look at a watch. What do you feel after some time?
Ans: Suffocated .
2) How long were you able to keep both of them closed?
Ans: 29 seconds .
| Name of the classmate | Breathing rate | |||
| Normal | After a brisk walk for 10 min | After running fast 100 cm | At rest | |
| A | 18 | 21 | 26 | 17 |
| B | 17 | 20 | 24 | 17 |
| C | 14 | 17 | 22 | 14 |
| D | 15 | 19 | 25 | 15 |
| Self | 14 | 18 | 24 | 13 |
Q) Paheli wants to know why we yawn when we are sleepy or drowsy .
Ans: We yawn because our breathing has showed when we are sleepy and there is less supply of oxygen. When we yawn, we draw in more oxygen and supply it to our tired oxygen.
Activity 10.4 – do the activity
Table 10.2
| Name of the classmate | Size of the chest (cm) | ||
| During inhalation | During exhalation | Difference in size | |
| A | 34 | 37 | 3 |
| B | 30 | 32 | 2 |
| C | 28 | 31 | 3 |
| D | 31 | 34 | 3 |
Activity 10.5 – do the activity :
1) What do the balloons in this model represent?
Ans: They represent our lungs.
2) Did you see any changes in the balloons?
Ans: Yes, when the rubber sheet was pulled down, the balloons expended. While, when the rubber sheet is pushed up, the balloons shrink.
3) What does the rubber sheet represent?
Ans: Diaphragm.
4) Boojho wants to know how much air person can hold in the lungs.
Ans: Around 500ml .
10.4 what do we breathe out?
1) Is there any change in the appearance of lime water?
Ans: Lime water turns milky.
2) Can you explain this change?
Ans: Lime water turns milky when carbon dioxide is passed through it. Since the air that we exhale contain carbon dioxide, lime water turns milky.
3) What do we exhale?
Ans: Carbon dioxide.
4) Do we exhale only carbon dioxide or mixture of gases along with it?
Ans: We exhale mixture of gases along with carbon dioxide.
5) If you exhale on a mirror, film of moisture appears on it surface. From where do these droplets come?
Ans: These droplets come from the water vapour in our exhaled air.
10.5 – breathing in other animals :
1. Boojho wants to know if cockroaches, snails, fish, earthworm, ants and mosquitoes also have lungs.
Ans: No, they don’t have lungs
2. Boojho has seen in television programme that whales and dolphin often come up to the water surface. They even release a fountain of water sometimes while moving upwards. Why do they do so?
Ans: The nostril of whale and dolphin are located at the top of their head which the use to inhale and exhale air. They often come on the surface to exhale out the air which looks like releasing fountain of water.
10.7 – Do plants also respire?
1) Paheli wants to know whether roots, which are underground also take in oxygen? If so, how?
Ans: Roots cells also need to take in oxygen to generate energy. They take up air spaces present between the soil particles.
2) Can you guess what would happen if a potted plant is ever watered?
Ans: If a potted plant is over watered, the roots of the plant will get air to respire. Hence the whole plant will die.
TEXT EXERCISES
1) Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans: While running, the athlete needs energy and for the release of energy, oxygen is required hence athlete breathes faster and deeper.
2) List the similarities and difference between aerobic and anaerobic respiration?
Ans:
Similarities :
a) in both food is broken down to smaller constituents .
b) energy released in both.
Differences:
Aerobic respiration Anaerobic respiration
1. Takes place in the presence of oxygen 1. Takes place in the absence of oxygen.
2. End products are carbon dioxide 2. End products are carbon
water and energy. dioxide and alcohol .
3) Why do we often sneeze when we inhale a lot of dust taken air?
Ans: When we inhale dust taken air, the dust particle sometimes, get past the hair in our nasal cavity which leads to irritation. As a result we sneeze which expels these dust particles.
4) Take three test tubes fill ¾ of each with water label them A, B and C. keep a snail in the test tube A, a water plant in test tube B and in C, keep a snail and plant both. Which test tube would have the highest concentration of CO2?
Ans: Test tube A because test tube A has snail which expels out CO2. In test tube C, the plant inhales CO2 there by decreasing it concentration.
5) Tick (√) the correct answer:
1) In cockroaches, air enters the body through _______ .
i) Lungs ii) Gills iii) Spiracles iv) Skin
2) During heavy exercise, we get cramps in the legs due to _________ .
i) Carbon dioxide ii) Lactic acid iii) Alcohol iv) Water
3) Normal range of breathing rate per minute in an average person at rest is ________ .
i) 9-12 ii) 15-18 iii) 21-24 iv) 30-33
4) During exhalation, the ribs __________ .
i) Move outwards ii) Move downwards iii) Move upwards iv) Do not move at all
Answers :
1) iii) 2) ii) 3) ii) 4) ii) .
6) Match the items in column 1 with those in column 2 :
| Column 1 | Column 2 |
| a) yeast | i) earthworms |
| b) diaphragm | ii) gills |
| c) skin | iii) alcohol |
| d) leaves | iv) chest cavity |
| e) fish | v) stomata |
| f) frog | vi) lungs and skin |
| vii) tracheae |
Answers :
a) iii) b) iv) c) i) d) v) e) ii) f) vi) .
7) Mark ‘T’ if the statements is true and ‘F’ if is false :
1. During heavy exercise the breathing rate of a person shows down. (T/F)
2. Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
3. Frogs breathe through their skins as well as their lungs (T/F)
4. The fishes have lungs for respiration. (T/F)
5. The size of the chest cavity increases during inhalation. (T/F)
Answers:
1. False (F) 2. False (F) 3. True (T) 4. False (F) 5. True (T) .
8) Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction upward, downward, or along the diagonals. Find the words for your respiratory system about those words are given below the square.
| S | V | M | P | L | U | N | G | S |
| C | Z | G | Q | W | X | N | T | L |
| R | M | A | T | I | D | O | T | C |
| I | Y | R | X | Y | M | S | R | A |
| B | R | H | I | A | N | T | A | Y |
| S | T | P | T | B | Z | R | C | E |
| M | I | A | M | T | S | I | H | A |
| S | P | I | R | A | C | L | E | S |
| N | E | D | K | J | N | S | A | T |
1. The air tube of insects .
2. Skeletal structures surrounding chest cavity .
3. Muscular floor of chest cavity .
4. Tiny pores on the surface of leaf .
5. Small opening on the sides of the body of an insects .
6. The respiratory organs of human beings .
7. The opening through which we inhale .
8. An organism with tracheal system .
Answers:
1. Tracheae 2. Ribs 3. Diaphragm 4. Stomata
5. Spiracles 6. Lungs 7. Nostrils 8. Ant .
9) The mountaineers carry oxygen with them because __________ .
a) At an altitude of more than 5km there is no air.
b) The amount of air available to a person is less than that available on the ground .
c) The temperature of air is higher than that on the ground.
d) The pressure of air is higher than that on the ground .
Ans: b) .