Life Processes

  • Question 113

    Draw the labelled diagram of the human respiratory system.


     Human respiratory system
    Question 114

    What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?


    The organisms that live in water use oxygen dissolved in surrounding water. Since air dissolved in water has fairly low concentration of oxygen, the aquatic organisms have much faster rate of breathing. Whereas the terrestial organisms take oxygen from the oxygen-rich atmosphere, through respiratory organs. So, they have much less breathing rate than aquatic organisms.

    Question 115

    What are the different ways in which glucose is oxidised to provide energy in various organisms?


    Different organisms oxidise glucose by different methods, some organisms use oxygen (Aerobic respiration) to break down the glucose into carbon-dioxide and water while others do not use oxygen ( Anaerobic respiration)to oxidise glucose
    In both the process the first step of break down of glucose (6 carbon molecule) takes place in the cytoplasm of cells of all organisms and gives a three carbon molecule compound called Pyruvate.

    Further break down of pyruvate takes place in different manners in different organisms.

    (i) Anaerobic respiration: This process takes place in absence of oxygen e.g., in yeast during fermentation. In this case pyruvate is converted into ethanol and carbon dioxide.
    (ii) Aerobic respiration: In aerobic respiration break down of pyruvate takes place in presence of oxygen to give rise 3 molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than anaerobic respiration.
    (iii) Lack of oxygen: Sometimes, when there is lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid (3 carbon molecule compound). Formation of lactic acid in muscles causes cramp.

     Break down of glucose by various pathways during cellular respiration.

    Question 116

    How is oxygen and carbon dioxide transported in human beings?


    (a) Transport of oxygen: The oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body. In human beings, the respiratory pigment, called haemoglobin present in the red blood corpuscles carries oxygen to different tissues of the body.

    (b) Transport of carbon dioxide: Carbon dioxide is more soluble in water. Hence is mostly transported from body tissues in the dissolved form in our blood plasma to lungs. Where it diffuses from blood to air in the lungs.

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