(a) (i) List five excretory organs found in living organisms. (ii) Give one example of...
(a) (i) List five excretory organs found in living organisms.
(ii) Give one example of an organism in which each type is found.
(b) (i) state two ways in which the excretory organs of earthworm is similar to that of mammals.
(ii) Give three differences between them.
(c) Describe the mechanisms of opening and closing of the stomata
Explanation
(a)(i) Excretory organs found in living organisms: Lung, kidney, skin, liver and nephridia
(ii) Lungs - man, Kidney - man, Skin - man, Liver - man, Nephridia - earth worm, Contractile vacuole - paramecium, Stomata / Lenticel - plants, Flame cells - tape worm, Malpigian tubules - insects.
(b)(1) Two ways in which the excretory organ of earth worm is similar to that of mammals are:
(1) Both possess structure for filtering excretory products.
(2) Each is well supplied with blood.
(ii) Differences between mammals and earth worm:
| Mammals | Earth worm |
-Not ciliated. -Has no special tissue for storing waste products. -Has only one outlet for discharging. | - Ciliated. - Has special tissues for storing some excretory products. - Has an outlet per segment hence possesses many outlets. |
(c) Mechanism of opening and closing of the stomata:Each stoma is enclosed by guard cells. Guard cell has chloroplast and is also elastic. During photosynthesis, sugar is formed and this increases the concentration of cell. sap. Guard cell receives water by means of osmosis and becomes turgid. This makes the stoma to open. During the night, sugar in the guard cell is converted to starch. This makes the osmotic concentration of guard cell to reduce. Water is lost lay the guard cells through osmosis to the surrounding. This makes the guard cell to be flaccid, hence stoma closes.