Mmed1005 Q6

Front 1

With respect to the light sensitive of rods and cones. Which of the following statements is correct?

Select one:
a. Rods are sensitive to the light at the 420nm wavelength.

b. Rods are sensitive to the light at the 560nm wavelength.

c. Rods are sensitive to the light at the 460nm wavelength

d. Rods are sensitive to the light at the 700nm wavelength.

e. Rods are sensitive to the light at the 500nm wavelength

Back 1

e.

Front 2

The far point of vision for someone with and emmetropic eye is:

Select one:
a. 2 metres

b. 5 metres

c. 3 metres

d. 4 metres

e. 6 metres

Back 2

e.

Front 3

Which of the following cells are able to generated action potentials?

Select one:

a. Horizontal cells

b. Ganglion cells

c. Amacrine cells

d. Photoreceptors

e. Bipolar cells

Back 3

b.

Front 4

Which of the following statements relating to rods and cones is incorrect?

Select one:

a. Rods are very sensitive and are suited to night vision and are perceived only in gray-tones

b. Rods are most abundant in the periphery of the retina

c. Cones have lower sensitivity than rods and need bright light for activation

d. The three cones absorb different wavelengths of light

e. Cones participate in converging pathways and many cones may ultimately feed into each ganglion cell resulting in acute vision

Back 4

e.

Front 5

Which of the following statements relating to the constriction of the pupil is correct?
Select one:

a. Sympathetic stimulation of the circular muscles in the iris causes the iris to constrict

b. Parasympathetic stimulation of the radial muscles within the iris causes the iris to constrict

c. Sympathetic stimulation of the radial muscles in the iris causes the iris to constrict

d. Parasympathetic stimulation of the circular muscles in the iris causes the iris to constrict

e. Parasympathetic and sympathetic stimulation of both the circular and the radial muscles in the iris are needed to cause the iris to constrict

Back 5

d.

Front 6

With respect to the light sensitive of rods and cones. Which of the following statements is correct?

Select one:

a. L cones are sensitive to the light at the 600nm wavelength.

b. L cones are sensitive to the light at the 420nm wavelength

c. L cones are sensitive to the light at the 560nm wavelength.

d. L cones are sensitive to the light at the 500nm wavelength

e. L cones are sensitive to the light at the 460nm wavelength

Back 6

c.

Front 7

With respect to the conjunctiva which of the following statements is not correct?

Select one:

a. The conjunctiva is continuous with the under surface of the eye lid

b. Blood vessels within the conjunctiva are visible

c. The conjunctiva merges with the outer ring of the iris

d. The conjunctiva is a thin membrane which covers the visual part of the sclera

e. The conjunctiva receives blood from the anterior ciliary artery

Back 7

c.

Front 8

Which of the following statements relating to light transduction by photoreceptors is incorrect?

Select one:

a. Released opsin activates a G protein

b. Light isomerises retinal to release opsin

c. G protein signal transduction activates phosphodiesterase

d. Activated phosphodiesterase attaches cGMP to a sodium channel

e. The closing of sodium channels results in hyperpolarisation

Back 8

d.

Front 9

Which of the follow statements relating to human colour perception is correct?

Select one:

a. Humans can distinguish about 400 levels of brightness, 200 different hues, and 10 steps of saturation resulting in about 1.5 million distinct colours.

b. Humans can distinguish about 500 levels of brightness, 50 different hues, and 200 steps of saturation resulting in about 4 million distinct colours.

c. Humans can distinguish about 200 levels of brightness, 500 different hues, and 20 steps of saturation resulting in about 2 million distinct colours.

d. Humans can distinguish about 200 levels of brightness, 200 different hues, and 500 steps of saturation resulting in about 4 million distinct colours.

e. Humans can distinguish about 500 levels of brightness, 200 different hues, and 20 steps of saturation resulting in about 2 million distinct colours

Back 9

e.

Front 10

When light activates the photoreceptors which of the follow events is correct.

Select one:

a. There is an increase in the neurotransmitter glutamate released from the photoreceptor.

b. The photo receptor depolarizes the ganglion cell which generates an action potential.

c. The photoreceptor generates an action potential which travels down the optic nerve.

d. The transmembrane potential of the photoreceptor is depolarized.

e. The inhibition of the bipolar cell is decreased and stimulates the ganglion cell

Back 10

e.