Life Processes- Respiration notes
v Respiration- The process by which digested food is broken down with the help of Oxygen to release energy.
Types of respiration- (i) Aerobic respiration (ii) Anaerobic respiration
Aerobic respiration
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Anaerobic respiration
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1. Takes place in presence of Oxygen.
2. End products- Carbon dioxide & Water
3. More energy is released.
4. Takes place in Cytoplasm & Mitochondria
5. Complete oxidation of glucose takes place.
6. It occurs in most organisms.
7. Equation-
Glucose→ Pyruvate→ CO2 + H2O + Energy
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1. Takes place in absence of Oxygen.
2. End products- Ethanol & Carbon dioxide or
Lactic Acid.
3. Less energy is released.
4. Takes place only in Cytoplasm.
5. Incomplete oxidation of glucose takes place.
6. It occurs in certain bacteria, yeast & certain tissues of higher organisms. E.g. In humans during vigorous exercise, when the demand for Oxygen is more than the supply, muscle cells respire anaerobically for some time.
7. Equation-
In Yeast-
Glucose→ Pyruvate→ Ethanol + CO2 + Energy
In muscle cells -
Glucose→ Pyruvate→ Lactic acid + Energy
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- Some common features of Respiratory organs-
- (i) Large surface area- for greater rate of diffusion of respiratory gases.
- (ii) Thin permeable walls – to ensure easy diffusion & exchange of gases.
- (iii) Extensive blood supply- Respiratory organs are richly supplied with blood vessels for quick transport of gases.
- Gaseous exchange in plants-
- Process – Diffusion
- Direction of diffusion depends on- (i) Environmental conditions (ii) Requirement of the plant.
§ Day time- Carbon dioxide given out during respiration is used for photosynthesis. Therefore only Oxygen is released, which is a major activity during the day.
§ Night time – Only respiration takes place. Therefore only Carbon dioxide is released, which is a major activity during the night.
- Gaseous exchange in animals-
§ Terrestrial animals- take Oxygen from the atmosphere.
§ Aquatic animals- take Oxygen dissolved in water. (Oxygen content is low in water, therefore they breathe faster.
- Human Respiratory system-
- External nostrils → Nasal cavity → Trachea→ Bronchi → Bronchioles →Alveoli
§ Rings of cartilage present in the throat ensure that the trachea (air passage) does not collapse when there is less air in it.
§ Lungs – (i) Present in the thoracic cavity.
(ii) They are spongy, elastic bags consisting of Bronchi, Bronchioles and
Alveoli.
Alveoli.
Refer to figure 6.9 page no. 104 of N.C.E.R.T Text book)
- Respiration occurs in two phases-
- (i) External-Breathing, which is a mechanical process. (ii) Internal - Cellular respiration
- Mechanism of breathing – It includes : (i)Inhalation (ii) Exhalation
- Exchange of gases-
§ Unicellular organisms- By Diffusion
§ Animals- (i) As the body size is large, diffusion alone is not enough.
(ii) Respiratory pigments also required.
§ (iii) Respiratory pigment in human beings is Haemoglobin, which is present in red blood corpuscles.
§ (iv) It has very high affinity for Oxygen.
(v) Carbon dioxide is more soluble in water than Oxygen, so it gets dissolved in blood and is thus transported.
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