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

Long Answer Questions

Teacher's Note:
1. Present the answer as a four-row table for full marks.
2. Breathing is one step within respiration.

Question 2. How do ribs and diaphragm help in respiration?
Answer:
Inspiration (breathing in):
1. The ribs are lifted up and the diaphragm is flattened.
2. The chest cavity becomes larger.
3. The pressure inside the lungs falls, so air moves into the lungs.
Expiration (breathing out):
4. The ribs move downwards and inwards, and the diaphragm moves up to its dome shape.
5. The chest cavity becomes smaller and the pressure inside rises, so air moves out of the lungs.
In simple words: The ribs and the diaphragm change the size of the chest, and that moves air in and out.

Teacher's Note:
1. Draw the chest cavity getting bigger and smaller to understand the pressure change.
2. Air always moves from high pressure to low pressure.

Question 3. Explain the process of respiration.
Answer:
In humans, respiration has two stages, inspiration and expiration.
Inspiration: the ribs are lifted up and the diaphragm is flattened, so the chest cavity becomes larger. The pressure inside falls, so air from outside (higher pressure) enters the lungs (lower pressure).
When the oxygen-rich air reaches the alveoli, oxygen passes into the blood and carbon dioxide passes out of it. The blood carries the oxygen to the different parts of the body, where it is used to break down glucose and release energy.
Expiration: the ribs and diaphragm return to their original position, the chest cavity becomes smaller and the pressure inside rises, so air with carbon dioxide is pushed out of the lungs.
Glucose + Oxygen → Carbon dioxide + Water + Energy
In simple words: We breathe in oxygen, the cells use it to get energy from glucose, and we breathe out carbon dioxide.

Teacher's Note:
1. Cover both stages, inspiration and expiration, and end with the equation.
2. Mention where the oxygen goes after the alveoli.