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प्रश्न
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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उत्तर
(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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संबंधित प्रश्न
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.
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
Name the defect of vision in a person:
whose far point is less than infinity
The near point of a long-sighted person is 50 cm from the eye.
- Can she see clearly an object at:
- a distance of 20 cm?
- at infinity?
- To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
- if the person is an old man
- if the person is a young man
Have a look at the posture of this girl who is reading a book and answer the questions which follow:
Name the problem she is facing.
State one role of ciliary muscles in the human eye.
State the main functions of the following:
Tears
Complete the following sentence with appropriate word :
An inability to focus on nearby objects due to loss of elasticity of the lens with age is called Iris.
Observe the figure whether it is correct or not and explain the phenomenon.
