Class 10 CBSE Science : Biology Lesson 6 | Life Processes Part 3 – Respiration

1. Why do we need food ? What impact of it is seen in the body?

Ans: Ingestion of food during nutrition process proves beneficial when it is broken down completely to produce energy. This energy is used for the various life processes of the body.

2. Explain the generation of energy in our body.

Ans:

• The first step is the break down of glucose, a six-carbon molecule into a 3-carbon molecule called pyruvate. This process takes place in the cytoplasm.
• Later, the pyruvate may be converted to ethanol and carbon dioxide and energy in anaerobic respiration (absence of oxygen).
• Or the pyruvate is broken down using oxygen in the mitochondria (aerobic respiration)
• This process breaks down the three carbon molecule pyruvate into 3 molecules of carbon dioxide and water (aerobic respiration) and energy.
• Sometimes because of the lack of oxygen in our muscle cells, another pathway for generating energy (by breaking down pyruvate) is taken. The pyruvate is converted to lactic acid which is a 3 carbon molecule.

These are the various pathways to break down glucose.

3. Why do we get cramps?

Ans: Sometimes, when we run or exercise, there might arise a lack of oxygen in our muscle cells. In the lack of oxygen, the cells convert pyruvate into lactic acid and energy. This accumulation of lactic acid causes cramps in our muscles.

4. How is energy absorbed in the body at the cellular level?

Ans:

• The energy generated in the body is immediately used to synthesize a molecule of ATP (Adenosine Triphosphate) which fuels all the energy needs of the cells.
• Then the ATP molecule is broken down into a fixed amount of energy which drives all the endothermic reactions of the cell.

5. How is an ATP molecule made?

Ans: The energy released from the respiration process is used to make an ATP molecule from ADP (Adenosine diphosphate) and inorganic phosphate.

This ATP molecule is then used to drive all endothermic reactions in the cells.

6. What happens when the terminal phosphate linkage is broken using water in an ATP?

Ans: Energy equivalent to 30.5 KJ / molecule is released.

7. What are the uses of ATP ?

Ans:

• Contraction of muscles
• Protein Synthesis
• Conduction of nervous impulses

8. What is respiration substrate?

Ans: The substance used to derive energy is called respiration substrate.

Eg: Carbohydrates, Vitamins

9. State the equation for break down of glucose.

Ans:

C6 H12 O 6 + 6 O2 > 6 CO2 + 6 H2O + 38 ATP

Glucose + Oxygen > Carbon dioxide + Water + Energy

10. What are the main events happening in a plant in terms of gaseous exchange?

Ans : During night : No photosynthesis —–> Major Event : CO2 Elimination

During Day : Photosynthesis occurs —> Major Event : Oxygen release

11. What are the characteristics of a respiratory surface?

Ans:

• Permeable to gases
• Thin layer ( 1mm or less)
• Richly supplied with blood vessels / body fluids
• Allows maximum intake of oxygen at a time

12. Why is breathing of aquatic organisms more faster than terrestrial organisms?

Ans: Amount of dissolved oxygen available is comparatively lower than the atmospheric oxygen. Thus, aquatic organisms such as fish breathe fast to take up more oxygen.

13. How is exchange of gases takes place in terrestrial organisms?

Ans:

• Oxygen is taken in by different organs in different organisms.
• The organ has a structure which increases the surface area in contact with the oxygen rich atmosphere.
• This surface is very fine and delicate
• In order to protect this layer, it is placed inside the body and there are passages which take the air to and from.

14. How is respiratory system in humans arranged?

Ans:

• Air enters through the nostrils, it’s filtered by fine hairs and mucus in the nostrils.
• Air goes into throat and into the lungs. Throat has rings of cartilage to ensure that air passage does not collapse.
• In the lungs, the air passage divides into smaller and smaller branches ending in balloon-like structures called alveoli.
• Alveoli’s wall is filled with blood vessels and network of capillaries.
• The diaphragm contracts when we breathe in and expand when we breathe out.

15. What actually happens when we take a breath?

Ans:

• When we breathe in, oxygen enters the air passage and the alveoli and fills it.
• The blood containing carbon dioxide flows into the alveoli for release and at the same time takes in the oxygen and is transported to the heart for systematic circulation.
• As we breathe out, the carbon dioxide is released through the nostrils.

16. How does the exchange of gases takes place so quickly? How do the lungs manage it?

Ans: During the breathing cycle, the lungs maintain a residual volume of air so that there is sufficient time for the exchange of oxygen and carbondioxide to take place.

17. Why is smoking injurious to health?

Ans:

• The upper part of the respiratory tract is covered with hair-like cilia which protects the entering air from dust and chemical substances.
• When a person smokes, the smoke destroys all these cilia.
• This results in the entering of dust and harmful particles into the lungs.
• This causes infection, cough and lung cancer.

18. What are respiratory pigments and what is their use?

Ans:

• In large animals, diffusion alone can’t take the oxygen to all parts of the body.
• So, respiratory pigments take up the oxygen and transport it to the oxygen needy cells.

19. What is the human respiratory pigment?

Ans :

• Hemoglobin is the pigment and has high affinity for oxygen.
• Present in red blood corpuscles
• Carbon dioxide is more soluble than oxygen, so it is in the dissolved form of carbon dioxide in the blood.