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Question
The diagram given below represents the cross-section of the human eye:
(i) Name the parts labeled 1—12.
(ii) What is the function of the part marked ‘10’?
(iii) What would happen if part ‘5’ is damaged or cut?
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Solution
(i)
1. Sclerotic
2. Choroid
3. Retina
4. Yellow spot or fovea
5. Optic nerve
6. Blindspot
7. Lens
8. Aqueous humour
9. Pupil
10. Iris
11. Vitreous humour
12. Cornea.
(ii) The function of the part marked ‘10’, the iris, is to regulate the amount of light that enters the eye so that too much light does not damage the delicate cells of the retina.
(iii) The person would not see because the sensations from the eye would not reach the brain.
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RELATED QUESTIONS
Given below is a diagram showing a defect of human eye. Study it and answer the following questions.
(i) Name the defect shown in the figure.
(ii) Give reason for this defect of eye in human being.
(iii) Name the type of lens used to correct the eye defect.
List three common refractive defects of vision. Suggest the way of correcting these defects.
What is the far point and near point of the human eye with normal vision?
Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
Name the defect of vision in a person:
whose far point is less than infinity
Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.
The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract
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Tears
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Write whether the following is true or false:
A convex lens is used for correcting myopia.
