Engineering Chemistry MCQ (The Photochemistry of Vision)
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The Photochemistry of Vision
1. Which vitamin is important for vision?
a) Vitamin A
b) Vitamin B
c) Vitamin C
d) Vitamin D
Explanation: Vitamin A is important for vision. It is also known as retinol. It is
required by the retina of the eye.
2. In the mechanism of vision, cis-retinal is converted into trans-retinal.
Explanation: Cis-retinal can absorb light at a specific wavelength. By absorbing
visible light, it undergoes isomerization and cis-retinal is converted into transretinal.
3. Retina is made up of which type of cells?
a) Rods and cones
b) Rids and cones
c) Rods and coans
d) Rods and rhodopsin
Explanation: Retina is made up of two types of cells. They are rods and cones. They
are light sensitive photoreceptor cells.
4. Which of the following is incorrect?
a) Retina is made up of rods and cones
b) Cones are lesser in number as compared to rods
c) Rods are more sensitive than cones
d) Cones are responsible for vision in dim light
Explanation: Retina is made up of two types of cells. They are rods and cones. Rods
are more sensitive than cones. Cones are fewer in numbers than rods. Rods are responsible for vision in dim light.
5. Rhodospin is a ______ pigment in the rod cells of retina.
Explanation: Rhodospin is a red pigment in the rod cells of the retina. It is extremely
sensitive to light. So, it works only in low light.
6. Rhodospin is a combination of opsin and _______
Explanation: Rhodospin is a combination of opsin and 11-cis-retinal. Opsin is a
protein and it is colorless. 11-cis-retinal is highly conjugated aldehyde.
7. Select the incorrect statement from the following.
a) Rods are found at the periphery of the retina
b) Cones are at the centre of the retina
c) Rods has high resolution compared to cones
d) Cones have high resolution compared to rods
Explanation: Rods are found at the periphery of retina whereas cones are found at
the centre of the retina. Cones have high resolution as compared to rods.
8. All animals possess both rods and cones.
Explanation: Some animals do not possess both rods and cones. Owls have rods
and can see only in dim light. Pigeons have cones and can see only in bright light.
9. Which scientist first discovered that rod cells contain rhodospin?
a) Franz Boll
b) Benjamin Franklin
c) Robert Lewis
d) Andrew Boll
Explanation: Rod cells contain rhodospin was first discovered by German
physiologist Franz Boll. Molecular weight of human rhodospin is 41000 and it has 348 amino residues.
10. A disorder in which rod cells in the retina lose their ability to respond to light is called as ______
a) Color blindness
b) Night blindness
c) Day blindness
d) Retina blindness
Explanation: A disorder in which the rod cells in the retina lose their ability to
respond to light is called night blindness. Hence, we cannot see clearly in dim light
because of such type of retinal disorder.