question_answer

  State reason for the following (a) Trachea does not collapse when it has insufficient air. (b) Aquatic animals breathe rapidly. (c) Haemoglobin is present in RBC in humans.

Answer:

                  (a) The wall of trachea are lined by cartilaginous rings that helps in maintaining the rigidity of the trachea. Hence, the trachea do not collapse in insufficient air.                  (1) (b) Aquatic animals utilise the oxygen dissolved in water for respiration. Since,  the amount of dissolved oxygen is fairly low compared to the amount of oxygen in air, the rate of breathing is faster in aquatic organisms.                                                        (1) (c) Haemoglobin is present in RBC in human beings. It is a respiratory pigment, that helps in easy and faster transport of oxygen all through the body.                                          (1)