Questions covered are:
1. Why do we respire?
2. What is cellular respiration?
3. Write the difference between aerobic and anaerobic respiration?
4. Why do we get muscle cramps after heavy exercise?
5. What is breathing?
6. What makes up the respiratory system?
7. Write the Pathway of Breathing in Humans ?
8. How do we breathe?
9. How do different organisms breathe?
10. Why do plants also respire?
11. Difference Between Respiration and Breathing
Book Back Questions with Answers:
***********************************************************************************************************
1. Why do we respire?
We respire to provide energy to our body, which is essential for performing all life processes.
- Every cell in our body requires energy to carry out functions like digestion, movement, repair, and growth.
- The food we eat, especially glucose, contains stored energy. This energy is released when glucose is broken down during respiration.
- Oxygen plays a crucial role in this process. It is transported to all parts of the body through the blood. In the cells, oxygen helps in the breakdown of glucose into carbon dioxide and water, releasing energy in the form of ATP (Adenosine Triphosphate).
- Respiration happens continuously to provide a constant supply of energy, even when we are resting, sleeping, or reading. Without respiration, living organisms cannot survive.
2. What is cellular respiration?
Cellular respiration is the process by which energy is released from food inside the cells of an organism.
- It occurs in every cell of the body and is vital for providing energy needed for activities like movement, growth, and repair
- In this process, glucose (obtained from food) is broken down to produce energy
- Cellular respiration can be of two types:
- Aerobic Respiration: This occurs in the presence of oxygen. Glucose is completely broken down into carbon dioxide and water, releasing a large amount of energy.
- Glucose –> carbon dioxide + water + energy.
- Anaerobic Respiration: This occurs in the absence of oxygen. Glucose is partially broken down into substances like alcohol (in yeast) or lactic acid (in muscles), releasing less energy.
- Glucose –> ethanol + carbon dioxide + energy
- Example: When we exercise heavily, our muscles may temporarily perform anaerobic respiration, producing lactic acid. This results in less energy and causes muscle cramps.
3. Write the difference between aerobic and anaerobic respiration ?
| Feature | Aerobic Respiration | Anaerobic Respiration |
| Oxygen Requirement | Requires oxygen. | Does not require oxygen. |
| Location in Cell | Occurs in mitochondria. | Occurs in cytoplasm. |
| End Products | Carbon dioxide and water. | Alcohol and carbon dioxide (in yeast) or lactic acid (in humans). |
| Energy Released | Produces more energy (36 ATP molecules per glucose). | Produces less energy (2 ATP molecules per glucose). |
| Organisms | Occurs in humans, plants, and most animals. | Occurs in certain bacteria, yeast, and human muscles under limited oxygen. |
Example: Human muscles perform anaerobic respiration during intense exercise, producing lactic acid, which causes cramps.
4. Why do we get muscle cramps after heavy exercise?
- During heavy exercise, our body needs a lot of energy. However, the oxygen supply to our muscles may become insufficient.
- In such cases, our muscles perform anaerobic respiration to meet the energy demand.
- Anaerobic respiration produces lactic acid as a by-product instead of carbon dioxide and water.
Glucose lactic acid + energy
- The accumulation of lactic acid in the muscles causes pain and cramps.
- A hot water bath or a massage improves blood circulation, increasing the oxygen supply to the muscles. This helps break down the lactic acid into carbon dioxide and water, relieving the cramps.
5. What is breathing?
Breathing is the process of taking in oxygen-rich air (inhalation) and expelling carbon dioxide-rich air (exhalation).
- It is a continuous and essential process required for respiration.
- Oxygen from the air we inhale is transported to all parts of the body, where it is used to release energy by breaking down glucose.
- Carbon dioxide, a waste product of respiration, is expelled from the body during exhalation.
- Breathing rate (the number of breaths per minute) can change based on physical activity. For humans, the typical respiratory rate for a healthy adult at rest is 12–18 breaths per minute.
- During exercise, the breathing rate increases to supply more oxygen to the body.
6.What makes up the respiratory system?
Nose Mouth Throat (pharynx) Voice box (larynx) Windpipe (trachea) Airways (bronchi) Lungs.
7. Write the Pathway of Breathing in humans?
8. How do we breathe?
Breathing involves the movement of air in and out of the lungs. It is controlled by the diaphragm and ribcage.
- Inhalation:
- When we inhale, the diaphragm moves downward, and the ribs move outward.
- This increases the size of the chest cavity, allowing the lungs to expand.
- Air rich in oxygen rushes into the lungs.
- Exhalation:
- When we exhale, the diaphragm moves upward, and the ribs move inward.
- This reduces the size of the chest cavity, forcing air out of the lungs.
- The exhaled air contains carbon dioxide, a waste product of respiration.
- The breathing process is continuous and happens without our conscious effort.
9. How do different organisms breathe?
Different organisms have different methods of breathing depending on their structure and habitat:
- Humans and mammals: Use lungs to take in oxygen and release carbon dioxide.
- Fish: Use gills to extract oxygen dissolved in water.
- Insects: Have small openings called spiracles and air tubes called tracheae for breathing.
- Earthworms: Breathe through their moist skin. Oxygen diffuses through the skin into their body.
- Plants: Use tiny pores on their leaves called stomata and air spaces in roots to exchange gases.
10. Why do plants also respire?
Plants respire like animals to release energy for their activities.
- Every part of a plant, including roots, stems, and leaves, needs energy to grow and function.
- During respiration, plants take in oxygen and break down glucose to release energy, carbon dioxide, and water.
- In leaves, the exchange of gases occurs through tiny pores called stomata.
- In roots, oxygen from the air spaces between soil particles is absorbed.
11.Difference Between Respiration and Breathing
| Aspect | Respiration | Breathing |
| Definition | Respiration is the biochemical process of breaking down glucose in cells to release energy. | Breathing is the physical process of inhaling oxygen-rich air and exhaling carbon dioxide-rich air. |
| Purpose | To release energy required for all life activities. | To supply oxygen to the body and remove carbon dioxide. |
| Occurs In | Takes place in the cells of the body (cellular level). | Takes place in the respiratory organs (lungs, nostrils, diaphragm). |
| Process | It involves chemical reactions where glucose is broken down into carbon dioxide and water with the release of energy. | It involves the movement of air into and out of the lungs. |
| Types | Two types: Aerobic respiration (with oxygen) and Anaerobic respiration (without oxygen). | No types. It is a single process involving inhalation and exhalation. |
| Energy Release | Energy is released in the form of ATP (Adenosine Triphosphate). | No energy is directly released during breathing. |
| Organ Involvement | Happens in cells (using mitochondria). | Involves organs like the nose, windpipe, lungs, ribs, and diaphragm. |
| Voluntary or Involuntary | Completely involuntary and happens continuously in all living cells. | Mostly involuntary but can be controlled voluntarily for a short time (e.g., holding your breath). |
| End Products | Produces carbon dioxide, water, and energy. | Produces no chemical products. It only helps in gas exchange. |
Book Back Questions with Answers:
1. Why does an athlete breathe faster and deeper than usual after finishing the race?
After a race, an athlete breathes faster and deeper to replenish the oxygen levels in the body and remove excess carbon dioxide produced during intense exercise. This helps in muscle recovery and restores the body to its resting state.
2. List the similarities and differences between aerobic and anaerobic respiration.
Similarities:
- Both processes involve the breakdown of glucose to release energy.
- Both are essential for providing energy to cells.
Differences:
- Aerobic respiration requires oxygen, whereas anaerobic respiration does not.
- Aerobic respiration produces more energy (ATP) and the byproducts are carbon dioxide and water. Anaerobic respiration produces less energy and the byproducts are lactic acid (in animals) or ethanol and carbon dioxide (in yeast).
3. Why do we often sneeze when we inhale a lot of dust-laden air?
Sneezing occurs when dust particles irritate the sensitive lining of the nose. The body triggers a sneeze as a reflex to expel the dust and protect the respiratory system from harmful particles.
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 both a snail and a plant. Which test-tube would have the highest concentration of CO2?
Test-tube A, which contains only the snail, would have the highest concentration of CO2. This is because the snail exhales carbon dioxide during respiration, and there are no plants to absorb it. In test-tube B, the water plant absorbs CO2 during photosynthesis, and in C, the plant would help absorb the CO2 produced by the snail.
5. Tick the correct answer:
(a) In cockroaches, air enters the body through (iii) spiracles
(b) During heavy exercise, we get cramps in the legs due to the accumulation of (ii) lactic acid
(c) Normal range of breathing rate per minute in an average adult person at rest is: (ii) 15–18
(d) During exhalation, the ribs (ii) move downwards
6. Match the items in Column I with those in Column II:
- (a) Yeast – (iii) Alcohol
- (b) Diaphragm – (iv) Chest cavity
- (c) Skin – (vi) Lungs and skin
- (d) Leaves – (v) Stomata
- (e) Fish – (ii) Gills
- (f) Frog – (i) Earthworm
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. – F
(ii) Plants carry out photosynthesis only during the day and respiration only at night. – F
(iii) Frogs breathe through their skins as well as their lungs. – T
(iv) The fishes have lungs for respiration. – F
(v) The size of the chest cavity increases during inhalation. – 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 — upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.
· The air tubes of insects – Tracheae
· Skeletal structures surrounding chest cavity – Ribs
· Muscular floor of chest cavity – Diaphragm
· Tiny pores on the surface of leaf – Stomata
· Small openings on the sides of the body of an insect – Spiracles
· The respiratory organs of human beings – Lungs
· The openings through which we inhale – Nostrils
· An anaerobic organism – Yeast
· An organism with tracheal system – Insect
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.
As altitude increases, the air pressure decreases, which means there is less oxygen available at higher altitudes. Mountaineers carry oxygen to ensure they have enough oxygen for survival when the oxygen levels are lower than what is available at sea level.
Useful links: