Class 7 Science Chapter 6 Question Answers - Respiration in Organisms

Short Answer Questions

Ans: We respire to use the oxygen to oxidise our food and release energy. This is similar to burning but a slower process. it also needs respiratory enzymes. Respiration is a slower process than burning, and the energy released can be stored for later use. 

C₆ H₁₂ O₆+ O₂------------------> H₂O+ CO₂+energy

Q2: Why should we eat regularly?

Ans: The food has stored energy which is released during respiration, thus we should eat regularly.

Q3: What happens to the air we breathe in?

Ans: The air we breathe is transported to every part of the body, and ultimately, it is transported to each cell; in the cells, oxygen in the air helps in the breakdown of food, and this process of breakdown of food in the cell with the release of energy is called cellular respiration.

Q4: Explain cellular respiration

Ans: The air we breathe in transported to every parts of body and ultimately it is transported to each cell, in the cells, oxygen in the air helps in the breakdown of food, this process of breakdown of food in the cell with the release of energy is called cellular respiration. Cellular respiration occurs in the cells of all organisms.

Q5: Differentiate between aerobic and anaerobic respiration.

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Q6: Explain similarities between aerobic and anaerobic respiration.

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1. Both aerobic and anaerobic respiration are necessary for the survival of living organisms.
2. In both types of respiration, the food is broken, and energy is released for the functioning of an organism.
3. In both types of respiration, Carbon Dioxide, Water and Energy are produced finally.

Q7: Why is the human breathing mechanism called tidal breathing?

Ans:  The human breathing mechanism is called tidal breathing because air comes in and out using the same path.

Q8: Humans use yeast every day. What is yeast?

Ans: If we want to make our own bread, we can buy yeast in the grocery store. This yeast consists of little brown grains. The little brown grains of yeast may not seem to be alive, but if we put them in water with sugar, the yeast will carry out cellular respiration and grow. We can grow yeast in a test tube filled with water and sealed with a balloon. Under anaerobic conditions, yeast carries out alcoholic fermentation, so it produces lactic acid and energy.

Q9: Explain respiration in yeast.

Ans: Yeast is a single-celled organism that respires anaerobically and, during this process, yields alcohol. Yeast gets energy through anaerobic respiration; in the absence of oxygen, glucose breaks down into oxygen and carbon dioxide. The equation for the reaction is as follows: 

Glucose in the absence of oxygen > alcohol + carbon dioxide + energy

Q10: Why does an athlete breathe faster and deeper than usual after finishing the race?

Ans: The food has stored energy, which is released during respiration. Therefore, all living organisms respire to get energy from food by breathing the air. During heavy exercise, fast running, cycling, walking for many hours or lifting heavy weights, the demand for energy is high. Therefore, to meet the extra demand for energy, an athlete breathes faster and deeper than usual after finishing the race.

Q11: Why do we often sneeze when we inhale a lot of dust-laden air?

Ans: When we inhale a lot of dust-laden air, the dust particles get trapped in the hair present in our nasal cavity. However, sometimes, these particles may get past the hair in the nasal cavity. Then, they irritate the lining of the cavity, which results in us sneezing. Sneezing expels these foreign particles from the inhaled air, and dust-free, clean air enters our bodies.

Q12: Why do mountaineers carry oxygen with them?

Ans: Mountaineers carry oxygen with them because the amount of air available to a person is less than that available on the ground.

Q13: Why do we get muscle cramps after heavy exercise?

Ans: During heavy exercise, the demand for energy is high. However, the supply of oxygen to produce energy is limited. Then, anaerobic respiration takes place in the muscle cells to fulfil the demand for energy. 

Glucose in the absence of oxygen > Lactic Acid + Energy The cramps occur only when the muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.

Q14: Why do we feel hungry after a physical activity?

Ans:  During physical activity, we need more energy. Whenever a person needs extra energy, he/she breathes faster. As a result, more oxygen is supplied to our cells. It speeds up the breakdown of food and releases more energy. Due to the rapid breakdown of food, we feel hungry.

Q15: Write short notes on inhalation.

Ans: The process of taking in of air rich in oxygen into the body is called ‘inhalation’. During inhalation, ribs move up and outwards, and the diaphragm moves down. This movement increases space in our chest cavity, and air rushes into the lungs. Exhalation is the process of giving out of air giving out of air rich in carbon dioxide is known as ‘exhalation’. During exhalation, ribs move down and inwards while the diaphragm moves up to its former position. This movement reduces the size of our chest cavity, and air is pushed out.

Q16: How does the exchange of gases occur in breathing?

Ans: When we inhale air, it passes through our nostrils to the nasal cavity. From the nasal cavity, the air reaches our lungs. The exhaled air follows the same route to go out. Breathing in and out involves the movement of the diaphragm and the rib cage.

Q17: Write short notes on gills.

Ans: Gills in fish help them to use oxygen dissolved in water and thus, help them in breathing. Gills are projections of their skin. These are well supplied with blood vessels for the exchange of gases.

Q18: How do the plants breathe in oxygen?

Ans: In plants, each part can independently take in oxygen from the air and release carbon dioxide. Leaves of plants have tiny pores called ‘stomata’ for the exchange of oxygen and carbon dioxide. Roots take up air from the pores (air spaces) present between the soil particles.

Q19: Do the plants also respire?

Ans: Like all other organisms, plants also respire for their survival. They take oxygen from the air and give out carbon dioxide. In the cells, oxygen is used to break down glucose into carbon dioxide and water, as in other organisms.

Q20: How do we breathe?

Ans: We take in air through our nostrils; when we inhale air, it passes through our nostrils into the nasal cavity, and from there, it reaches our lungs through the windpipe. Lungs are present in the chest cavity, which is surrounded by ribs on the sides; the diaphragm forms the floor of the chest cavity. Breathing involves the movement of the diaphragm and the rib cage. During inhalation ribs move up and outwards and diaphragm moves down, because of this movement space in our chest cavity increases and air ruses into the lungs. During exhalation ribs move down and inward and diaphragm moves up to its former position, this reduces the size of chest cavity and air is pushed out of the lungs.

Q21: Explain all body parts involved in respiration.

Ans: We take in air through our nostrils; when we inhale air, it passes through our nostrils into the nasal cavity, and from there, it reaches our lungs through the windpipe. Lungs are present in the chest cavity, which is surrounded by ribs on the sides; the diaphragm forms the floor of the chest cavity. Breathing involves the movement of the diaphragm and the rib cage.

Q22: What happens when we inhale air? in exhaled air.

Ans: During inhalation, ribs move up and outwards, and the diaphragm moves down; because of this movement, space in our chest cavity increases and air rushes into the lungs.

Q23: What happens in the process of exhalation?

Ans: During exhalation ribs move down and inward and diaphragm moves up to its former position, this reduces the size of chest cavity and air is pushed out of the lungs.

Q24: Why should we cover our noses while sneezing?

Ans: We should cover our nose while sneezing so that the foreign particles expelled during sneezing do not get inhaled by other persons.

Q25: What role does hair present in the nasal cavity play in the process of respiration?

Ans: Air around us contains various unwanted particles like smoke, dust, pollens, etc. During inhalation of air, these particles get trapped in the hair of the nasal cavity, and thus, these hairs allow clean air to enter our body.

Q26: What is the total percentage of oxygen and carbon dioxide in inhaled air and exhaled air?

Ans: The percentage of oxygen and carbon dioxide in inhaled air is 21% and 0.04%, respectively, and the percentage of oxygen and carbon dioxide in exhaled air is 16.4% and 4.4%, respectively.

Q27: Explain respiration in cockroach.

Ans: A cockroach has a small opening on the side of its body, which is called a spiracle. Oxygen-rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body. In the same way, carbon dioxide from the cells goes into the tracheal tube and moves out through spiracles.

Q28: Explain respiration in insects

Ans: A cockroach has a small opening on the side of its body, which is called a spiracle. Oxygen-rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body. In the same way, carbon dioxide from the cells goes into the tracheal tube and moves out through spiracles.

Q29: Explain respiration in earthworms.

Ans: Earthworms breathe through their skins; the skin of an earthworm feels moist and slimy on touching, and gases can pass easily through them.

Q30: Explain respiration in water animals.

Ans: Water animals have gills that help them to use oxygen dissolved in water. Gills are projections of the skin that are well-supplied with blood vessels for the exchange of gases.

Q31: How does respiration occur in plants?

Ans: In plants, the roots take in air present in the soil, and leaves have tiny pores called stomata that help in the exchange of gases. The breakdown of glucose in plant cells is similar to that in other living beings.

Q32: Draw a labelled diagram showing the inhalation and exhalation process in human beings.

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Q33: Draw a labelled diagram of the insect’s tracheal system.

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Long Answer Questions

Q1: Explain the two types of respiration.

Ans: 

1. Both aerobic and anaerobic respiration are necessary for the survival of living organisms.
2. In both types of respiration, the food is broken, and energy is released for the functioning of an organism.
3. In both types of respiration, carbon dioxide, water, and energy are produced.

Q2: Explain the process of breathing in insects and fishes.

Ans: A cockroach has a small opening on the side of its body, which is called a spiracle. Oxygen-rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body. In the same way, carbon dioxide from the cells goes into the tracheal tube and moves out through spiracles.

Water animals have gills that help them to use oxygen dissolved in water. Gills are projections of the skin that are well-supplied with blood vessels for the exchange of gases.