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The Eye - Part 3

Please answer the following ten multiple choice questions.

1)The ability of the eye to distinguish two nearby points is called
A) Accomodation
B) Pupillary light reflex
C) Refraction
D) Visual acuity

2) How many different photopigments are contained in the rods and cones of the retina?
A) One
B) Two
C) Three
D) Four

3) The light 'receptor' of the rod is called
A) Transducin
B) Rhodopsin
C) Phosphodiesterase
D) Absorbin

4) A single photon can be detected by the eye because one molecule of rhodopsin can activate many molecules of phosphodiesterase, a process called
A) Addition
B) Absorption
C) Amplification
D) Reflection

5) How is phototransduction in cones different from that in rods?
A) Cones have different forms of opsins
B) Cones have different forms of transducin
C) Cones substitute phosphodiesterase with guanylate synthase
D) Sodium channels in cones close in response to light, while rod channels open in response to light

6) Which of the following are involved in dark adaptation?
A) Pupil dilation
B) Regeneration of bleached rhodopsin
C) Adjustment of retinal circuitry
D) All of the above

7) Which of the following are true of M cells?
A) They are important for the detection of stimulus movement
B) They are more sensitive to high-contrast stimuli than are P cells
C) They have slowly conducting axons
D) They respond to stimuli in the receptive field center with a sustained discharge of action potentials

8) Which of the following are examples of parallel processing?
A) The presence of M, P and nonM-nonP ganglion cells
B) ON and OFF- center ganglion cells
C) Having 2 eyes
D) All of the above

9) Most of the focusing power of our eye is due to the
A) Lens
B) Fovea
C) Cornea
D) Vitreous humor

10) The neurotransmitter released by photoreceptors (mostl likely glutamate)
A) Has inhibitory effects on OFF-center bipolar cells
B) Has excitatory effects on ON-center ganglion cells
C) Has excitatory effects on ON-center bipolar cells
D) Has inhibitory effects on ON-center bipolar cells

Solution Preview

1D
Visual acuity is the eye's ability to distinguish two points that are very close to each other. This ability depends on many factors, but especially on the precision of the eye's refraction and the ratio of cones to rods at a given location on the retina.

2B
Rhodopsin is the photopigment in rods, Opsin in cones; therefore, we have 2 general types of photopigments. Cones can have 3-types of opsins.

3B
Rhodopsin is the photopigment in rods

4C
A single molecule of activated opsin in the disk membrane can activate 500 ...

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