16 Questions
What is the function of the choroid?
To keep the eye dark by absorbing diffused light falling on it and to avoid internal reflections within the eye.
What is the normal diameter of the pupil?
1 mm
What is the role of the crystalline lens?
To provide the finer adjustment of focal length required to focus objects at different distances on the retina.
What is the composition of the sclerotic?
Tough, white, and opaque
What part of the eye refracts most of the light rays into the eye?
Cornea
What is the function of the iris?
To control the light level inside the eye.
What is the function of the optic nerve?
To carry electrical signals to the brain.
What happens to the focal length of the eye lens when the ciliary muscles contract?
It increases.
Where is the yellow spot situated?
At the center of the retina.
What is the purpose of the blind spot on the retina?
It does not have light sensitive cells (rods and cones) and no signal is sent to the brain when the image is formed on this part.
Why does the chick wake up late in the morning and go to sleep early in the evening?
The chick's retina consists of very few rod shaped cells, so it can only see in bright light.
Why are bees able to see ultra-violet light but human beings cannot?
The retina of bees contains cone cells which are sensitive to ultra-violet light, while human beings do not have those cone cells.
What is the function of the retina in the eye?
To serve as a sensitive screen for the reception of the image formed by the lens system of the eye.
What is the role of the ciliary muscles in controlling the eye lens?
They control the focal length of the eye lens.
Where does the optic nerve attach itself?
To the choroids.
What is the significance of the two important spots on the retina?
The yellow spot is most sensitive to light and the blind spot does not have light sensitive cells, affecting the visibility of objects.
Test your knowledge about the human eye and its essential parts described in Chapter 2 of Human Eye and Colorful World. Explore the functioning and structure of the eye through this quiz.
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