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 
           Anaerobic respiration 
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
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

  • 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.
                               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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