week 6

Which of the following statements relating to the macular lutea is correct?Select one:
A. Due to structural changes, light falls directly onto photo receptors in the macula lutea. 
B. The fovea is the outer ring of the macula lutea
C. The macular lutea contains a high density of rods.
D. There is considerable light refraction at the macula lutea.
E. The density of rods decreases as you move from the macula lutea to the periphery of the retina

Which of the follow statements relating to human colour perception is correct?Select one:
a. Humans can distinguish about 200 levels of brightness, 200 different hues, and 500 steps of saturation resulting in about 4 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 400 levels of brightness, 200 different hues, and 10 steps of saturation resulting in about 1.5 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.

Which of the following statements relating to light transduction by photoreceptors is incorrect?Select one:
A. G protein signal transduction activates phosphodiesterase
B. Light isomerises retinal to release opsin
C. The closing of sodium channels results in hyperpolarisation
D. Released opsin activates a G protein
E. Activated phosphodiesterase attaches cGMP to a sodium channel 

Which of the following cells are able to generated action potentials?Select one:
A. Ganglion cells 
B. Horizontal cells
C. Bipolar cells
D. Amacrine cells
E. Photoreceptors

With respect to the light sensitive of rods and cones. Which of the following statements is correct?Select one:
A. S cones are sensitive to the light at the 460nm wavelength
B. S cones are sensitive to the light at the 420nm wavelength 
C. S cones are sensitive to the light at the 520nm wavelength
D. S cones are sensitive to the light at the 700nm wavelength.
E. S cones are sensitive to the light at the 600nm wavelength.

Which of the following statements relating to rods and cones is incorrect?Select one:
A. Rods are most abundant in the periphery of the retina
B. Cones have lower sensitivity than rods and need bright light for activation
C. Rods are very sensitive and are suited to night vision and are perceived only in gray-tones
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 

Which of the following statements relating to the visual pathway to the brain is correct?
A. The primary visual cortex is part of the parietal lobe
B. Both the left and right visual cortex processes information from both eyes
C. Visual information from the temporal region of each retina is transferred to the opposite side of the brain
D. Visual information from both the nasal and temporal region of the retina of one eye is transferred to the lateral genticulate nucleus on the opposite side of the brain
E. Visual information from the nasal region of the retina is transferred to superior colliculus on the opposite side of the brain

With respect to the light sensitive of rods and cones. Which of the following statements is correct?Select one:
A. M cones are sensitive to the light at the 700nm wavelength.
B. M cones are sensitive to the light at the 420nm wavelength.
C. M cones are sensitive to the light at the 460nm wavelength
D. M cones are sensitive to the light at the 640nm wavelength.
E. M cones are sensitive to the light at the 520nm wavelength

With respect to the light sensitive of rods and cones. Which of the following statements is correct?
A. Rods are sensitive to the light at the 420nm wavelength.
B. Rods are sensitive to the light at the 700nm wavelength.
C. Rods are sensitive to the light at the 500nm wavelength 
D. Rods are sensitive to the light at the 560nm wavelength.
E. Rods are sensitive to the light at the 460nm wavelength

With respect to the conjunctiva which of the following statements is not correct?Select one:
A. Blood vessels within the conjunctiva are visible
B. The conjunctiva is continuous with the under surface of the eye lid
C. The conjunctiva is a thin membrane which covers the visual part of the sclera
D. The conjunctiva receives blood from the anterior ciliary artery
E. The conjunctiva merges with the outer ring of the iris