Special Senses Worksheet Answers

1. The diagram shows an eye of a mammal. In the table below add the names of the structures indicated by the letters.

CHOICES: Aqueous humour; choroid; conjunctiva; fovea; optic nerve; cornea; iris; lens; retina; sclera; vitreous humour; pupil

A	Lens
B	Conjunctiva
C	Cornea
D	Iris
E	Pupil
F	Anterior chamber
G	Sclera
H	Choroid
I	Retina
J	Fovea
K	Optic nerve
L	Posterior chamber

2.Insert the correct term in the table below. Some terms may be used more than once.

CHOICES: Aqueous humour; Choroid; Conjunctiva; Iris; Fovea; Optic nerve; Blind spot; Cornea; Sclera; Retina; Vitreous humour; Pupil; Nictitating membrane

Term	Description
Aqueous humour	1. Fluid that fills the anterior chamber of the eye.
Sclera	2. The white of the eye.
Fovea	3. Area of the retina that lacks rods and cones.
Choroid	4. Coating that provides nutrients to eye. Becomes the iris in the front of the eye.
Retina	5. Layer containing the rods and cones.
Vitreous humour	6. Jelly-like substance filling the posterior cavity of the eyeball.
Choroid	7. Heavily pigmented coating that prevents light scattering within the eyeball: reflects light in nocturnal animals.
Iris	8. Coloured structure that controls the size of the pupil.
Fovea	9. Area of the retina of most detailed vision.
Cornea	10. Most anterior part of the sclera—the window on to the world.
Sclera	11. Outer coating of tough, fibrous connective tissue.
Pupil	12. Aperture of the eye. Where the light enters.
Conjunctiva	13. The delicate membrane that covers the front of the eyeball.
Nictitating membrane	14. The third eyelid.
Optic nerve	15. The nerve that takes nerve impulses from the retina to the brain.

3. Are these statements about the eye true or false? If false give the correct answer.

1. Prey animals like the rabbit have a large area of binocular vision. F Prey animals like the rabbit have a large area of monocular vision so they can see predators approaching and only a small area of binocular vision.

2. The rods of the retina function in dim light and do not respond well to colour. T

3. The lacrimal glands secrete fluid that washes the outer surface of the eye and keeps it moist. T

4. The conjunctiva is the inner lining of the eyeball. F The conjunctiva is the fine membrane covering the cornea of the eye.

5. When the eye focuses both the lens and the cornea change in shape. F Only the lens changes shape. The shape of the cornea is constant.

6. The cones of the retina are more numerous in the region of the eye known as the fovea. T

7. Vitamin E is required in the diet to make the visual pigment found in the cells of the retina. F vitamin A is the vitamin required to make the visual purple of the sensory cells of the retina. It is found in carrots and green vegetables.

8. The size of the pupil changes in different light intensities. T

9. The parasympathetic nervous system brings about dilation (widening) of the pupil. F The parasympathetic nervous system controls constriction of the pupil.

10. Nocturnal animals are usually colour-blind. T

4. Match the terms in the list below to the descriptions in the table.

A. Auditory ossicles; B. Pinna; C.Tympanic membrane; D. Cochlea; E. Ear canal; F. Eustachian tube; G. Vestibular organ; H.Middle ear I. Inner ear; J.Auditory nerve

Term	Description
Eustachian tube	1. Connects the pharynx (throat)and the middle ear to keep the air pressures equal.
Tympanic membrane or ear drum	2. Vibrates as sound waves hit it. Transmits these vibrations to the auditory ossicles.
Ear pinna	3. Animals can turn this towards the direction of the sound.
Auditory ossicles	4. The smallest bones in the body. They transmit sound vibrations across the middle ear.
Cochlea	5. Sound vibrations are converted here into electrical impulses.
Vestibular organ	6. Contains receptors for the sense of balance and movement.
Ear canal	7. This canal can harbour mites in cats and dogs.
Inner ear	8. The part of the ear consisting of the cochlea and vestibular organ.
Middle ear	9. The part of the ear that contains the ear ossicles.
Auditory nerve	10. The nerve that transmits nerve impulses from the cochlea to the brain

5. The diagram below shows an ear of a mammal. Add the labels below to the diagram.

Auditory ossicles; Pinna; Tympanic membrane; Cochlea; Ear canal; Eustacian tube; Semicircular canals; Outer ear; Middle ear; Inner ear; Auditory nerve

6. Rearrange these parts of the ear in the order in which sound waves travel to stimulate the cochlea.

Auditory ossicles; Tympanic membrane; Ear canal; Inner ear

Sound	Ear canal	Tympanic membrane	Auditory ossicles	Inner ear	Cochlea

7. Complete the statements below by adding the words in bold.

tongue; temperature; otoliths; olfactory; hairs; nose; pressure; vestibular; touch; cerebellum; semicircular canals

1. There are two parts to the vestibular organ. The first part consists of the semicircular canals which respond to changes in speed and direction of movement of the body.
2. The canals are filled with fluid and fine hairs that are stimulated when the head moves.
3. The receptor cells send nerve impulses along the vestibular nerve to the cerebellum in the brain.
4. The otolith organs form the second part of the vestibular organ. They contain tiny pieces of chalk called otoliths that stimulate hair cells and tell the animal which way up it is.
5. The special sense organ for taste are located on the tongue.
6. The sensory cells concerned with smell are called the olfactory organ. This is located in the nose.
7. In the skin, cells that sense temperature, pressure and touch are found.

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