GSEB Class 7 Science Solutions Chapter 10 Respiration in Organisms

Question 1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer: An athlete must run quickly during a race. Their body requires more power, which raises the need for oxygen to break down food. So, the athlete breathes faster and deeper to take in more oxygen.
In simple words: Athletes breathe faster because their body needs more energy, and more oxygen helps to make that energy.

Exam Tip: Focus on the increased energy demand and the role of oxygen in food breakdown as key points.

 

Question 2. List the similarities and differences between aerobic and anaerobic respiration.
Answer:
Differences:
Aerobic Respiration:

• This process happens when oxygen is present.
• A significant amount of power gets released.
• Food particles are broken down into water and carbon dioxide.

Anaerobic Respiration:

• This process happens when oxygen is absent.
• A small quantity of power gets released.
• Food particles are broken down into ethyl alcohol and carbon dioxide.

Similarities: Both aerobic and anaerobic respiration systems create power and release carbon dioxide.
In simple words: Aerobic respiration needs oxygen and makes lots of energy, while anaerobic respiration doesn't need oxygen and makes less energy. Both types of breathing create energy and give off carbon dioxide.

Exam Tip: Clearly distinguish between the presence/absence of oxygen, the amount of energy released, and the final products for both types of respiration.

 

Question 3. Why do we often sneeze when we inhale a lot of dust-laden air?
Answer: At times, dust bits, pollen, and similar things go past nasal hair and bother the inside of the nasal passage. We then sneeze because we want to remove these undesired bits, such as dust and pollen, from our bodies. This process lets only clean and fresh air enter our systems.
In simple words: We sneeze when dust or pollen irritates our nose, to push out the unwanted particles and breathe clean air.

Exam Tip: Mention the irritation of nasal lining by foreign particles and the body's reflex action to expel them for clean air intake.

 

Question 4. Take three test-tubes. Fill 3/4th 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?
Answer: The greatest amount of carbon dioxide will be present in test-tube A.
In simple words: Test-tube A will have the most carbon dioxide because the snail is breathing and releasing it.

Exam Tip: Remember that snails (animals) respire and produce CO2, while plants in the dark also respire, but in light, they photosynthesize and consume CO2. Test tube A has only the snail producing CO2.

 

Question 5. Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Answer: (a) (iii) Spiracles
In simple words: Cockroaches breathe using small holes on their body sides called 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
Answer: (b) (ii) Lactic acid
In simple words: Intense exercise makes lactic acid build up in muscles, causing cramps.

(c) The 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
Answer: (c) (ii) 15-18
In simple words: A typical adult's breathing rate when resting is usually between 15 and 18 breaths per minute.

(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer: (d) (ii) move downwards
In simple words: When you breathe out, your ribs naturally go down and inward.

Exam Tip: For MCQs, carefully read all options before selecting. Understand why each correct answer is chosen and why others are incorrect.

 

Question 6. Match the items in Column I with those in Column II:

Answer:In simple words: Match the organ or organism in the first column to its correct respiratory feature or associated term in the second column.

Exam Tip: Go through each item in Column I and connect it to the most suitable item in Column II, ensuring all items are correctly paired.

 

Question 7. Mark 'T' if the statement is true and 'F' if it is false:
1. During heavy exercise, the breathing rate of a person slows 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)
Answer:
1. False
2. False
3. True
4. True
5. True
In simple words:
1. False: When you exercise hard, your breathing usually speeds up, not slows down, to get more oxygen.
2. False: Plants perform photosynthesis during the day, but they respire (breathe) both day and night.
3. True: Frogs can breathe using both their skin and their lungs, depending on where they are.
4. True: This statement suggests that fishes use lungs for breathing, and the answer confirms this idea.
5. True: When you breathe in, your chest cavity expands and becomes larger.

Exam Tip: Carefully evaluate each statement for biological accuracy before marking it true or false.

 

Question 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.

1. The air tubes of insects
2. Skeletal structures surrounding the chest cavity
3. The muscular floor of the chest cavity
4. Tiny pores on the surface of the leaf
5. Small openings on the sides of the body of an insect
6. The respiratory organs of human beings
7. The openings through which we inhale
8. An anaerobic organism
9. An organism with a tracheal system
Answer:
1. Trachea
2. Ribs
3. Diaphragm
4. Stomata
5. Spiracles
6. Lungs
7. Nostrils
8. Yeast
9. Ant
In simple words: Search the letter grid to find terms related to how organisms breathe. These terms can be horizontal, vertical, or diagonal.

Exam Tip: Read each clue carefully and identify the corresponding biological term. Systematically search the word grid in all directions to locate the hidden words.

 

Question 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 the air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.
Answer: (b) The amount of air available to a person is less than that available on the ground.
In simple words: Mountaineers take oxygen tanks because higher up in the mountains, there isn't as much air to breathe as there is at sea level.

Exam Tip: Understand that atmospheric pressure and oxygen concentration decrease significantly at higher altitudes, making breathing difficult without supplemental oxygen.

Extended Learning Activities And Projects

 

Question 1. Observe fish in an aquarium. You will find flap-like structures on both sides of their heads. These are flaps that cover the gills. These flaps open and close alternately. On the basis of these observations, explain the process of respiration in the fish.
Answer: Fish use gills as their breathing organs. They have two gills, one on each side of their head. Gills are skin extensions that have many blood vessels for swapping gases. In some fish, a flap covers each gill, opening and closing in turns. This movement is linked to the opening and closing of the mouth. When a fish's mouth opens, it takes in water that moves over the gill. During this time, gases are exchanged in the gills. The gill flap (also known as the operculum) stays shut then. Once gas exchange finishes, the gill flap opens, and the water is pushed out.
In simple words: Fish breathe using gills, which are covered by flaps that open and close. Water enters the mouth, flows over the gills for gas exchange, and then exits when the flaps open.

Exam Tip: Describe the structure of gills, their location, and how the coordinated movement of the mouth and operculum facilitates water flow and gas exchange.

 

Question 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 of your area who smoke. If you have a smoker in your family, confront him with the material that you have collected.
Answer: Smoking causes smoke particles to settle on the breathing surface, which impacts how well oxygen is taken in and carbon dioxide is released from the body. Furthermore, the nicotine in tobacco smoke constricts blood vessels and irritates the windpipe. Therefore, smoke raises the amount of carbon dioxide, and persistent irritation can lead to T.B., bronchitis, and lung cancer.
In simple words: Smoking harms your lungs by coating them with smoke particles, making it hard to breathe. Nicotine also narrows blood vessels and irritates the throat, leading to serious health issues like T.B. and lung cancer.

Exam Tip: Explain the direct physical damage smoking causes to the respiratory system (particle deposition, reduced gas exchange) and the harmful effects of nicotine on blood vessels and airways, leading to serious diseases.

 

Question 3. Visit a doctor. Find out about artificial respiration. Ask the doctor:
(a) When does a person need artificial respiration?
(b) Does the person need to be kept on artificial respiration temporarily or permanently?
(c) From where can the person get a supply of oxygen for artificial respiration?
Answer:
(a) A person requires artificial oxygen supply when there's not enough oxygen, for example, due to lung or heart problems, or from drowning.
(b) Artificial respiration is a method to help a patient's organs by exchanging gases (oxygen and carbon dioxide). It's not a lasting fix. However, some individuals might be kept on it to stay alive, but they can't engage in work or other social activities.
(c) The patient receives oxygen from an oxygen cylinder that holds compressed oxygen gas.
In simple words:
(a) Someone needs artificial breathing when they don't get enough oxygen, like from lung issues or drowning.
(b) It's usually a temporary help to exchange gases, not a permanent solution for living a normal life.
(c) Oxygen for artificial breathing comes from a tank that holds compressed oxygen gas.

Exam Tip: For artificial respiration, identify the critical conditions necessitating it, clarify its temporary nature, and state the source of oxygen supply (oxygen cylinder).

 

Question 4. Measure the breathing rate of the members of your family and some of your friends. Investigate:
(a) If the breathing rate of children is different from that of adults.
(b) If the breathing rate of males is different from that of females.
If there is a difference in any of these cases, try to find the reason.
Answer:
(a) Yes, children typically breathe quicker than adults because they are more energetic and need more oxygen for their body processes.
(b) Yes, females generally have a faster breathing rate compared to males.
In simple words:
(a) Children breathe faster than adults because they are more active and use more oxygen.
(b) Females generally have a faster breathing rate than males.

Exam Tip: Consider how age and activity levels influence metabolic rates, which directly impacts oxygen demand and, consequently, breathing rate.