Theory question 101
Sense Organs(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 labelled diagram of the vertical section through the mammalian skin
Show the model answer
(a) Eye – sight; ear – hearing and balance; nose – smell; tongue – taste; skin – touch, pressure, pain, heat and cold
(b)(i) Long sight (hypermetropia): near objects are blurred; light from a near object is focused behind the retina because the eyeball is too short or the lens cannot become thick (convex) enough
(ii) Corrected with converging (convex) lenses, which bend the light so it focuses on the retina; diagrams: uncorrected eye with focus behind the retina, and corrected eye with convex lens and focus on the retina
(c) Labels: epidermis (cornified layer, granular layer, Malpighian layer), dermis, hair and hair follicle, sebaceous gland, erector muscle, sweat gland and duct, sweat pore, blood capillaries, nerve endings/sense receptors, subcutaneous fat
Long-sighted people see far objects clearly; the image of near objects forms behind the retina.