7. Answer the following:

(a) What is the function of the lacrimal gland and where is it situated in the body?

(b) In what two ways is the yellow spot different from the blind spot?

(c) Name an age-old eye defect. What causes it?

(d) What is meant by the power of accommodation of the eye?

(e) Mention the characteristics of the image that falls on the retina of the eye.

Solution:-

(a) They are found in the orbit’s upper sideward part. The gland’s secretion is poured over the front surface by six to twelve channels. The liquid, which primarily serves as a lubricant, is dispersed by the motions of the eyelids. Tears also help to keep the front surfaces of the eyes clean by wiping dust away.

(b) The yellow spot has the greatest number of sensory cells, especially cones. As a result, this is the brightest vision as well as the colour vision zone. Because there are no sensory cells here, this is a visionless zone. This is where the nerve fibres from all of the retina’s sensory cells converge and bundle together to form the optic nerve, which leaves the eyeball.

(c) Presbyopia is a disorder that affects older persons and causes them to be unable to see clearly close objects. Their lens becomes less flexible, causing them to become farsighted. A convex lens corrects this once again.

(d) The image of an object should be in sharp focus in each eye to view it clearly. The power of accommodation of the eye is the process of focussing the eye to view objects at varied distances.

(e) The image on the retina is inverted and real.