(a) Write the reaction that occurs when glucose breaks down anaerobically in yeast.
(b) Write the mechanism by which fishes breath in water.
(c) Name the balloon like structures present in lungs. List its two functions.
(d) Name the respiratory pigment and write its role in human beings.

Explanation

(a) Break down of glucose anaerobically in yeast
` " Glucose " overset(" Glycolysis") underset("in the cytoplasm") to " Pyruvic acid " overset("In the absence ") underset(" of oxygen") to 2C_(2)H_(5)OH + 2CO_(2) + 2ATP`
(b) The fisher have special organs of breathing called 'gills'. The fish breathes by taking in water through its mouth and forces it past the gills, the gills extract dissolved oxygen from this water which is then taken up by the blood. The water then goes out through the gills slits.
(c) The balloon like structures present in lungs are called alveoli.
Two funcations
(i) The alveoli provide a surface where the exchange of gases can take place.
(ii) The walls of alveoli are covered by extensive network of blood vessels or capillaries in which oxygen from alveoli dissolves and are carried by the blood to the hear for pumping . In the same way, carbon dioxide from the body cells are carried by the blood capillaries to the alveoli from where it goes out of the body.
(d) In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. This pigment is present in the red blood corpuscles.