NCERT Solutions for Class 7 Science Chapter 6 Respiration in Organisms with Important Questions and answers according to the Latest Syllabus Of JKBOSE and CBSE NCERT Books
1. Define cellular respiration.
- Answer: Cellular respiration is the process by which cells obtain energy from glucose. During cellular respiration, glucose and oxygen are converted into carbon dioxide, water, and energy.
2. Why does an athlete breathe faster and deeper than usual after finishing the race?
- Answer: An athlete breathes faster and deeper than usual after finishing a race to increase the intake of oxygen and remove carbon dioxide more rapidly. This helps to replenish the oxygen levels in the body and remove the lactic acid that has accumulated in the muscles during strenuous exercise.
3. List the similarities and differences between aerobic and anaerobic respiration.
- Answer:
- Similarities:
- Both processes produce energy.
- Both occur in cells.
- Differences:
- Aerobic respiration requires oxygen, whereas anaerobic respiration does not.
- Aerobic respiration produces more energy compared to anaerobic respiration.
- The end products of aerobic respiration are carbon dioxide and water, while anaerobic respiration produces lactic acid or ethanol and carbon dioxide.
- Similarities:
4. Why do we often sneeze when we inhale a lot of dust-laden air?
- Answer: We sneeze when we inhale a lot of dust-laden air because the dust particles irritate the lining of the nasal cavity, triggering a reflex action to expel the foreign particles from the respiratory system.
5. 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?
- Answer: Test-tube A, which contains only the snail, would have the highest concentration of CO₂ because snails respire and produce carbon dioxide.
6. Tick mark (✔) the correct answer:
(a) In cockroaches, air enters the body through
- (i) lungs
- (ii) gills
- (iii) spiracles ✔
- (iv) skin
(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
(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
(d) During exhalation, the ribs
- (i) move outwards
- (ii) move downwards ✔
- (iii) move upwards
- (iv) do not move at all
7. Match the items in Column I with those in Column II:
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 |
(g) Cockroach | (vii) Tracheae |
8. 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)
- Answer: F
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
- Answer: F
(iii) Frogs breathe through their skin as well as their lungs. (T/F)
- Answer: T
(iv) The fishes have lungs for respiration. (T/F)
- Answer: F
(v) The size of the chest cavity increases during inhalation. (T/F)
- Answer: T
9. 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 – Tracheae
(ii) Skeletal structure surrounding chest cavity – Ribcage
(iii) Muscular floor of the chest cavity – Diaphragm
(iv) Tiny pores on the surface of the leaf – Stomata
(v) Small openings on the sides of the body of an insect – Spiracles
(vi) The respiratory organs of human beings – Lungs
(vii) The openings through which we inhale – Nostrils
(viii) An anaerobic organism – Yeast
(ix) An organism with tracheal system – Cockroach
10. 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 on the ground.
(d) The pressure of air is higher than that on the ground.
11. Give two examples of each of the following:
(1) Animals that breathe through gills:
- Fish: Goldfish, Shark
(2) Animals that breathe through spiracles:
- Insects: Cockroach, Grasshopper
(3) Animals that breathe through skin:
- Amphibians: Frog, Earthworm
Extended Learning – Activities and Projects of Respiration in Organisms
1. Observe fish in an aquarium. You will find flap-like structures on both sides of their heads. There 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.
- Answer: In fish, the flaps on the sides of their heads are called gill covers or opercula. When a fish breathes, it takes water in through its mouth. The water passes over the gills where oxygen is extracted, and carbon dioxide is expelled. The oxygenated water then exits through the gill slits, and the opercula open and close to facilitate this process.
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 from your teacher or parents. Find out the percentage of people who smoke. If you have a smoker in your family, confront him with the material that you have collected.
- Answer: This activity involves researching the harmful effects of smoking and gathering data on smoking prevalence. You can create a report on how smoking affects the respiratory and cardiovascular systems, leading to diseases such as lung cancer, chronic obstructive pulmonary disease (COPD), and heart disease. Share this information with family members or peers to raise awareness.
3. Visit a doctor. Find out about artificial respiration. Ask the doctor:
(a) When does a person need artificial respiration?
- Answer: A person needs artificial respiration when they are unable to breathe on their own due to conditions such as respiratory failure, cardiac arrest, severe respiratory distress, or during surgery under general anesthesia.
(b) Does the person need to be kept on artificial respiration temporarily or permanently?
- Answer: The need for artificial respiration can be temporary or permanent depending on the underlying condition. For example, during recovery from surgery, artificial respiration is temporary, whereas patients with irreversible damage to the respiratory muscles might require permanent support.
(c) From where can the person get supply of oxygen for artificial respiration?
- Answer: Oxygen for artificial respiration can be supplied from oxygen tanks, concentrators, or piped oxygen systems in hospitals. In emergency situations, portable oxygen cylinders are used.
4. Measure the breathing rate of the members of your family and some of your friends. Investigate.
- Answer: To measure the breathing rate, count the number of breaths taken in one minute while the person is at rest. Record the rates and compare them. The average resting breathing rate for an adult is 12-18 breaths per minute. Variations may occur due to factors such as age, fitness level, and overall health.