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.