Human eye and colourful world

Eye retina retains image on it for ______ of a second even after removal of object.

1/16th

Cornea of dead persons' eye is removed within ____ hours of death and transplanted in blind persons' eye.

6

_______ interprets these electrical signals.

Brain

A person using spectacles, contact lens or have been operated for cataract or suffering from hypertension can donate eyes. True / False

False

_____ is the distance of most distant point up to which a person can see object distinctly. It is_____ for normal vision.

Far point, infinity

______ is the most sensitive part of the eye that has nearly 70,000 sensitive cells which convey the electric impulses to the brain via ______.

Retina, optical nerve

____ present on the retina are sensitive to intensity of light and ______ are sensitive to colours of light.

Rods, cones

What are the defects of the eye?

The defects of the eye are myopia, hypermetropia, presbyopia, astigmatism, and colour blindness.

Eyes can be donated after death. State True / False

True

Redness of sky at sunrise or at sun set is due to ___________ .

atmospheric refraction

For curing presbyopia, ___________ are required.

bifocal lenses

Absence of all colours is ____ and presence of all in specific ratio is _____.

black, white

Colour blindness ______ be cured.

cannot

Focal length of eye lens can be varied with the help of _____

ciliary muscles

Colour of the iris determines the ______ of the eye.

colour

Hypermetropic person cured by using a ________ of suitable focal length.

convergent lens ( convex or convavo-convex)

Astigmatism is cured by using ______________.

cylindrical lens

Myopic person cured by using a ________ of suitable focal length.

divergent lens ( concave or convexo-concave)

Light sensitive cells get activated during illumination and produce ___________.

electrical signals

A ______ or _______ person can see far off objects clearly but cannot see near objects clearly.

hypermetropic, long sighted person

A person who cannot see far off objects clearly but can see near object clear is suffering from ______ or _______

myopia, short sightedness.

Eye is the most useful natural __________

optical instrument

The electrical signals are conveyed to the brain via ______.

optical nerves

Most sensitive part of the retina is called ________.

yellow spot