Biology Online Quiz for AIIMS Exam on “Neural Control and Coordination – Eye-2”.
1. What is the inner layer of the eye known as?
a) Sclera
b) Cornea
c) Choroid
d) Retina
Answer: d
Clarification: Each eyeball is surrounded by three layers. The outermost protective layer is the sclera. The middle one is known as choroid. The innermost layer is the retina. It contains light-sensitive photopigments.
2. Which of these structures hold the lens in place?
a) Cartilage
b) Tendons
c) Ligaments
d) Adherens junctions
Answer: c
Clarification: The lens present in the eye is a transparent crystalline structure through which light passes before it falls on the retina. The lens is held in place by the ligaments which are attached to the ciliary body.
3. Which of these is surrounded by the iris?
a) Cornea
b) Sclera
c) Pupil
d) Lens
Answer: c
Clarification: The iris is a continuation of the ciliary body. It is a part of the choroid. The pupil, which is the aperture located just in front of the transparent lens, is surrounded by the pigmented and opaque iris.
4. Which of these cells are not present on the retina?
a) Mast cells
b) Photoreceptor cells
c) Ganglion cells
d) Bipolar cells
Answer: a
Clarification: The retina is the innermost layer surrounding the eye. It contains three types of neural cells-the ganglion cells, the bipolar cells and the photoreceptor cells. The light entering the eye falls on the retina.
5. Which of these statements is false regarding photopigments of the eye?
a) Scotopic vision is a function of rods
b) Visual purple is a derivative of rhodopsin
c) They are light sensitive proteins
d) There are three types of cones
Answer: b
Clarification: Rods and the three types of cones are the photoreceptor cells of the retina. Photopigments are light sensitive proteins. Scotopic vision is a function of rods. Visual purple is also called rhodopsin.
6. To which of these colors are the cone cells of the eye unresponsive?
a) Red
b) Blue
c) Yellow
d) Green
Answer: c
Clarification: Rods and cones are the photoreceptor cells of the retina. There are three types of cone cells which are responsive to three different colors of light. These colors are red, blue and green, but not yellow.
7. The sensation of what color is produced when all cones are stimulated equally?
a) White
b) Black
c) Yellow
d) Purple
Answer: a
Clarification: Each type of cone cell is responsive to different colors of light and various degrees of combinations give sensations of different colors. when all cones are stimulated equally, a sensation white light is perceived.
8. What is the point of exit of optic nerves and entry of blood vessels in the eye?
a) Choroid
b) Fovea
c) Macula lutea
d) Blind spot
Answer: d
Clarification: The point on the retina from which optic nerves exit the eye and through which retinal blood vessels enter the eye is known as the blind spot. No photoreceptor cells are present in this region.
9. In which of these structures are cone cells densely packed?
a) Choroid
b) Blind spot
c) Fovea
d) Cornea
Answer: c
Clarification: Cone cells are densely packed in the fovea, which is the central pit of the macula lutea. The macula lutea is a yellow-pigmented region present near the center of the retina, which is the innermost layer of the eye.
10. The space between the cornea and the lens is called the vitreous chamber. True or false?
a) True
b) False
Answer: b
Clarification: The space between the cornea and the lens is known as the aqueous chamber. It contains a fluid known as aqueous humor. The space between the lens and the retina is known as the vitreous chamber.
11. Which of these is not a protein?
a) Iodopsin
b) Rhodopsin
c) Opsin
d) Retinal
Answer: d
Clarification: Iodopsin and rhodopsin are photosensitive pigments which are proteinaceous in nature. Opsin is also a protein. However, retinal is not a protein. It is an aldehyde of vitamin A.
12. In which of these structures is visual acuity the greatest?
a) Lens
b) Blind spot
c) Fovea
d) Cornea
Answer: c
Clarification: Visual acuity or resolution is the greatest at the fovea. The fovea is the central pit of the macula lutea, which is a yellow-pigmented region of the retina. The fovea contains a large number of cone cells.
13. Which of these does not take place when light falls on the photopigments of the eye?
a) Opsin undergoes conformational changes
b) Action potentials are generated in the ganglion cells
c) Retinal and opsin bind together
d) Potential differences are generated in the photoreceptor cells
Answer: c
Clarification: When light falls on the photopigments, retinal and opsin dissociate and opsin undergoes conformational changes. Potential differences are generated in the photoreceptor cells which lead to action potentials being generated in the ganglion cells.
14. Which of these structures are present on the retina?
a) Macula lutea
b) Macula densa
c) Macula adherens
d) Macula flava
Answer: a
Clarification: The retina is the innermost layer that surrounds the eye. It contains a yellow-pigmented region near its center at the posterior pole of the eye known as the macula lutea. The central pit of the macula lutea is the fovea.
15. Identify the structure in the given diagram.
a) Lens
b) Cornea
c) Iris
d) Pupil
Answer: b
Clarification: The given diagram is that of the cross section of the eye. The indicated structure is present at the anterior pole of the eye, on the outermost layer called sclera. It is identified to be the cornea.
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