Chapter 6
Respiration in Organisms
1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans: There are two main reasons why an athlete breathes heavily after a race:
Oxygen Debt: During intense exercise, the body's demand for oxygen to produce energy outpaces the lungs' ability to supply it. This creates an "oxygen debt" that needs to be repaid. By breathing faster and deeper, the athlete takes in more oxygen to deliver it to the muscles and replenish their stores.
Removing Waste Products: Intense exercise also leads to the buildup of lactic acid, a byproduct of energy production without sufficient oxygen (anaerobic respiration). Lactic acid buildup contributes to muscle fatigue and burning. Deeper breaths help bring fresh blood to the muscles, which carries away lactic acid and other waste products.
This heavy breathing, often called the "oxygen repayment phase," helps the athlete's body return to a normal state after exertion. It can take several minutes for their breathing to slow down and their oxygen debt to be settled.
2. List the similarities and differences between aerobic and anaerobic respiration.
Ans:
| Aerobic | Anaerobic |
|---|---|
| Takes place in the presence of oxygen | Takes place without oxygen |
| Complete break down of food | Partial break down of food |
| Carbon dioxide and water as the end product | Ethanol, carbon dioxide as the end product(in yeast) |
| Produces more energy | Produces less energy |
3. Why do we often sneeze when we inhale a lot of dust-laden air?
Ans: We sneeze when we inhale dust-laden air because it irritates the delicate lining inside our nose. Here's the breakdown:
Dust Invasion: When you breathe in dusty air, some particles get past the coarse hairs in your nostrils and reach the nasal cavity.
Irritation Alert: The lining of your nasal cavity is covered in sensitive cells. These cells detect the dust particles as irritants.
Sneeze Signal: The irritated cells send a signal to your brain through nerves.
Expulsion Action: Your brain interprets the signal as a need to expel the irritant. It triggers a complex reflex that involves forceful muscle contractions in your chest and diaphragm.
Explosive Eviction: This forceful contraction pushes air out of your lungs at high speed, carrying the dust particles with it. This is the sneeze!
Bonus Cleaning: Sneezing also causes your eyes to water and your throat muscles to contract. This combined effort helps to flush out any remaining dust particles and mucus, leaving your nasal passages clean.
In essence, sneezing is your body's way of kicking out unwanted guests (dust particles) from your respiratory system!
4. Take three test-tubes. Fill ¾th of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
Ans: The test tube with the highest concentration of CO2 would be Test Tube A (with only the snail).
Here's why:
- Snails respire: Snails, like most animals, take in oxygen (O₂) and release carbon dioxide (CO₂) as a waste product of cellular respiration.
- Water plants use CO2: The water plant in Test Tube B would utilize the CO2 produced by the environment and the snail in Test Tube C for photosynthesis. Photosynthesis consumes CO2.
- No consumption in Test Tube A: Since Test Tube A only has the snail, there's no organism to consume the CO2 the snail produces. This leads to a buildup of CO2 in the water.
Therefore, Test Tube A will have the highest concentration of CO2 as the CO2 produced by the snail has nowhere to go.
5. Tick the correct answer:
(a) In cockroaches, air enters the body through.
(i) lungs (ii) gills
(iii) spiracles (iv) skin
Ans: (iii) spiracles
(b) During heavy exercise, we get cramps in the legs due to the
accumulation of
(i) carbon dioxide (ii) lactic acid
(iii) alcohol (iv) water
Ans: (ii) lactic acid
(c) Normal range of breathing rate per minute in an average adult
person at rest is:
(i) 9–12 (ii) 15–18
(iii) 21–24 (iv) 30–33
Ans: (ii) 15–18
(d) During exhalation, the ribs
(i) move outwards (ii) move downwards
(iii) move upwards (iv) do not move at all
Ans: (ii) move downwards
6. Match the items in Column I with those in Column II:.
Column I Column II
(a) Yeast (i) Earthworm
(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
Ans:
| Column I | Column II |
|---|---|
| (a) Yeast | (iii) Alcohol |
| (b) Diaphragm | (iv) Chest cavity |
| (c) Skin | (i) Earthworm |
| (d) Leaves | (v) Stomata |
| (e) Fish | (ii) Gills |
| (f) Frog | (vi) Lungs and skin |
7. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) During heavy exercise the breathing rate of a person slows
down. (T/F)
(ii) Plants carry out photosynthesis only during the day and
respiration only at night. (T/F)
Ans: False
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
Ans: True
(iv) The fishes have lungs for respiration. (T/F)
Ans: False
v) The size of the chest cavity increases during inhalation. (T/F).
Ans: False
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 — upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.
(i) The air tubes of insects
Ans:
(ii) Skeletal structures surrounding chest cavity
Ans:
(iii) Muscular floor of chest cavity
Ans:
(iv) Tiny pores on the surface of leaf
Ans:
(vi) The respiratory organs of human beings
Ans:
(vii) The openings through which we inhale
Ans:
(viii) An anaerobic organism
Ans:
9. The mountaineers carry oxygen with them because
(a) At an altitude of more than 5 km 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) The amount of air available to a person is less than that available on the ground.
1. Observe fish in an aquarium. You will find flap like structures on both sides of their heads. These are flaps which cover the gills. These flaps open and close alternately. On the basis of these observations, explain the process of respiration in the fish.
Ans: Based on your observations of the fish in the aquarium, here's a breakdown of the respiration process in fish:
Flap Identification: The flaps you see are actually called gill covers. They protect the delicate gills located underneath them on either side of the fish's head.
Water Flow: Fish don't breathe air directly like us. They extract oxygen from the water surrounding them. As the fish swims, water enters its mouth or is drawn in through a slight opening in the gill cover.
Gill Action: The observed alternate opening and closing of the gill covers is what facilitates water flow over the gills. When the gill cover opens, water flows over the gills. When it closes, water is pushed out.
Gas Exchange: The gills themselves are feathery organs with a large surface area. They are covered in thin filaments rich in blood vessels. As water passes over the gills, dissolved oxygen in the water diffuses into the bloodstream through the gill filaments. At the same time, carbon dioxide, a waste product of cellular respiration, diffuses from the bloodstream into the water flowing over the gills.
Water Exit: With the next opening of the gill cover, the water that passed over the gills, now depleted of oxygen and containing carbon dioxide, is expelled.
Oxygen Delivery: The oxygen that diffuses into the bloodstream through the gills is then transported throughout the fish's body to its cells, where it's used for energy production.
In essence, the alternate opening and closing of the gill covers creates a continuous flow of water over the gills, allowing fish to extract oxygen for survival and release carbon dioxide waste.
2. Visit a local doctor. Learn about the harmful effects of smoking. You can also collect material on this topic from other sources. You can seek help of your teacher or parents. Find out the percentage of people of your area who smoke. If you have a smoker in your family, confront him with the material that you have collected.
Ans: Smoking is injurious to health as it leads to increased incidents of lung cancer, cancer of the urinary bladder and throat, gastric ulcers, cancer of bronchitis, and diseases such as emphysema, coronary heart disease, etc. Cigarette smoking affects nearly every organ, causes many diseases, and lowers smokers' health.
3. Visit a doctor. Find out about artificial respiration. Ask the doctor:
(a) When does a person need artificial respiration?
Ans: (a) A person requires artificial respiration during acute breathing problems. Under conditions when a person is not able to breathe normally, an artificial method of respiration is usually practiced. (b) Artificial respiration is provided to the patient temporarily till the person solves their breathing problems
(b) Does the person need to be kept on artificial respiration temporarily or permanently?
Ans: The person is kept on artificial respiration temporarily, until the person regains his health and starts breathing naturally.
(c) From where can the person get supply of oxygen for artificial
respiration?
(d) If the breathing rate of males is different from that of females.
Ans: The volume of the female lungs are somewhat smaller than that of a males lungs therefore women have a slightly faster breathing rate (again, it is because more oxygen is needed and more CO2 needs to be exhaled out of the body).
If there is a difference in any of these cases, try to find the reason.
Colour By: Himashree Bora.
