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प्रश्न
Give Reason:
Deficiency of vitamin A causes night blindness.
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उत्तर
Because the visual purple (Rhodopsin) of the rods is not formed in the absence of vitamin A.
संबंधित प्रश्न
What is the far point of a person suffering from myopia (or short-sightedness)?
Where is the near point of a person suffering from hypermetropia (or long-sightedness)?
A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is:
(a) astigmatism
(b) myopia
(c) presbyopia
(d) hypermetropia
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
Write whether the following is true or false:
A convex lens is used for correcting myopia.
Differentiate between:
Myopia and Hypermetropia.
Name the following:
The defect of the human eye caused due to the uneven surface of the cornea.
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?
Nearsightedness: elongated eyeball : : farsightedness: _______
Myopia and hypermetropia can be corrected by:
