Respiration in Organisms
NCERT Class 10 • Science • Chapter "Life Processes" | NCERT Class 7 • Science • Chapter "Respiration in Organisms"
Respiration in Organisms
Respiration is the process of releasing energy from food inside the cells. It is often confused with breathing, but breathing is only the physical exchange of gases, while respiration is the chemical breakdown that actually releases the energy the body uses.
Aerobic and Anaerobic Respiration
- Aerobic respiration takes place in the presence of oxygen and breaks glucose completely into carbon dioxide and water, releasing a large amount of energy.
- It occurs mainly in the mitochondria and is the normal mode in most organisms.
- Anaerobic respiration occurs without oxygen and releases much less energy.
- In yeast, anaerobic respiration gives alcohol and carbon dioxide, which is the basis of brewing and of bread rising.
- In human muscle during heavy exercise, the partial breakdown of glucose gives lactic acid, which causes cramps.
- The energy released is stored in the cell as ATP, the energy currency of the cell.
- Respiration occurs in every living cell at every moment, unlike photosynthesis which needs light.
- In plants, gas exchange happens through stomata in leaves and lenticels in stems.
- Fish take dissolved oxygen from water through gills, and earthworms breathe through their moist skin.
The Human Respiratory System
- Air enters through the nostrils, where hair and mucus filter dust and germs.
- It passes through the pharynx, larynx and trachea, which is kept open by rings of cartilage.
- The trachea divides into two bronchi, one entering each lung, which branch into finer bronchioles.
- Each bronchiole ends in balloon like alveoli, where gas exchange actually takes place.
- The alveoli have very thin walls and a rich blood supply, giving a huge surface for exchange.
- Breathing in is helped by the contraction of the diaphragm and rib muscles, which enlarges the chest cavity.
- Haemoglobin in red blood cells carries oxygen from the lungs to the tissues.
| Feature | Aerobic | Anaerobic |
|---|---|---|
| Oxygen | Required | Not required |
| End products | Carbon dioxide and water | Alcohol or lactic acid |
| Energy released | Large | Much less |
| Site | Mitochondria | Cytoplasm |
Alveoli — the tiny balloon like air sacs of the lungs where the exchange of oxygen and carbon dioxide takes place.
Exam me kaise aata hai
- Gas exchange in the lungs takes place in the — alveoli
- Anaerobic respiration in yeast gives — alcohol and carbon dioxide
- Muscle cramp is caused by — lactic acid
- The energy currency of the cell is — ATP
UPSC/State PSC ke liye
- Aerobic respiration yields far more energy because glucose is broken down completely, while anaerobic respiration stops partway.
- The alveoli provide an enormous surface in a small volume, which is why lung disease that destroys alveoli reduces oxygen uptake so severely.
Yahan confuse hote hain
✗ Breathing and respiration are the same | Breathing is gas exchange; respiration is energy release in cells | ✓
✗ Plants respire only at night | Plants respire day and night; photosynthesis alone needs light | ✓
✗ Anaerobic respiration releases more energy | Aerobic respiration releases far more energy | ✓
Ek nazar me
- Respiration releases energy from food inside cells; breathing is only gas exchange.
- Aerobic uses oxygen and gives carbon dioxide and water with much energy.
- Anaerobic gives alcohol in yeast and lactic acid in muscle.
- Alveoli in the lungs carry out gas exchange, and haemoglobin carries oxygen.