CBSE Class 7 Science Advanced Biology Respiration in Plants and Animals Short Answer Questions Set 01

Short Answer Questions

Question 1. What is the importance of respiration in plants?
Answer:
Respiration is the process by which plants produce energy for their different activities.
In it, glucose is broken down in the presence of oxygen to release energy: Glucose + Oxygen → Carbon dioxide + Water + Energy.
The oxygen taken in is carried to the cells, where it is used to break down glucose.
In simple words: Plants need energy to live and grow, and they get it by respiration.

Teacher's Note:
1. Plants make glucose by photosynthesis but get usable energy only through respiration.
2. Mention the word equation to earn full marks.

Question 2. How are our lungs protected?
Answer:
The lungs are protected from injuries and shock by a double covering called the pleural membranes.
The space between the two membranes is filled with pleural fluid, which gives further protection and acts like a cushion.
The ribs, which form a cage around the chest, also protect the lungs.
In simple words: Two thin membranes with fluid in between cushion the lungs like a protective jacket.

Teacher's Note:
1. Name both the membranes and the fluid in your answer.
2. Ribs are the outer bony protection.

Question 3. 'Plants like mangroves have special mechanisms to respire'. Justify the statement.
Answer:
Mangroves grow in swampy areas where the soil is waterlogged and has little air.
To get air they have special roots called pneumatophores (breathing roots), which grow upwards out of the water.
These roots have breathing pores and allow aeration, so the plant can respire.
In simple words: Mangroves have breathing roots that stick out of the water and take in air.

Teacher's Note:
1. Link the habitat (swamp, little air) with the adaptation (breathing roots).
2. Use the term pneumatophores in the answer.

Question 4. After finishing a race an athlete breathes faster and deeper than normal. Why?
Answer:
During a race the muscles need a lot of energy, which is released by respiration.
To meet this extra demand, more oxygen is needed to break down glucose, so the athlete breathes faster and deeper to take in more oxygen.
In simple words: Hard exercise needs more energy, so the body takes in more oxygen quickly.

Teacher's Note:
1. Food has stored energy, and oxygen is needed to release it.
2. Deeper breaths bring in more air at one time.

Question 5. Do plants also breathe in oxygen? If yes, how?
Answer:
Yes, plants also take in oxygen.
They have tiny pores called stomata on their leaves through which gases such as oxygen enter.
Roots also take in air from the spaces between the soil particles.
In simple words: Plants take in oxygen through stomata and through their roots.

Teacher's Note:
1. Plants respire all the time, not only at night.
2. Remember both routes: leaves and roots.

Question 6. When we inhale too much of dust-laden air, we sneeze. Explain, why?
Answer:
The nose has fine hairs and a mucus lining that trap the dust particles in the air we breathe in.
When too much dust comes in, some particles are not trapped and irritate the lining of the nasal cavity.
This irritation makes us sneeze to throw the dust out.
In simple words: Sneezing is the body's way of pushing out dust that irritates the nose.

Teacher's Note:
1. Hairs and mucus form the first filter of the respiratory system.
2. Sneezing is a protective reflex.

Question 7. It is commonly observed that we get cramps after heavy exercise. Give reason.
Answer:
During heavy exercise the muscles need a lot of energy, but the supply of oxygen is limited.
So the muscle cells respire anaerobically (without oxygen) to meet the need.
This makes lactic acid, which collects in the muscles and causes cramps.
In simple words: Without enough oxygen the muscles make lactic acid, and that causes cramps.

Teacher's Note:
1. Link cramps with lactic acid and anaerobic respiration.
2. A rest and a massage help the body clear the lactic acid.

Question 8. It is observed that mountaineers carry oxygen at high altitudes. Give reason.
Answer:
The air at high altitudes is thin, so the amount of oxygen available there is much less than on the ground.
So mountaineers carry oxygen cylinders to get enough oxygen for breathing.
In simple words: The air on high mountains has less oxygen, so climbers carry their own.

Teacher's Note:
1. Less oxygen means less energy for the body, so the climber tires quickly.
2. This idea also explains why people breathe faster at high places.