(a) List the principal sense organs in mammals and their functions.
(b) (i) Describe the eye defect in which only distant objects are seen clearly.
(ii) How can it be corrected? Illustrate your answer with labelled diagrams.
(c) Make a large diagram of the vertical section through the mammalian skin.
Explanation
(a) The principal sense organs in mammals are:
(i) The eyes for seeing or viewing
(ii) The nose olfactory organ for smell or smelling
(iii) Ear for hearing, balancing and sense of position
(iv) Tongue for taste using the taste bud (bitter, sour and sweet tastes)
(v) Skin for touch, detection of temperature, pressure, pain, heat and cold.
(b)(i) This type of defect is known as long sightedness (hypermetropia). inability to focus near objects clearly but can see distant objects clearly. It is as a result of short eyeball, or the lens and ciliary muscles which has lost their elasticity, Light rays from near objects are normally focused behind the retina
(ii) The defect can be corrected by using a convex lens which coverages the light rays entering the eye to focus on the retina. Long sight is corrected by convex lens. The convex lens shorten the focal length, converge rays of light entering the eye from near object to focus on the retina.