BIO 465 - CH 11

1. 1The iris....

   1. Aregulates the amount of light entering the eye.
   2. Bcovers the cornea, shielding it from harmful UV rays.
   3. Capplies tension to the lens.
   4. Dis responsible for the refraction of light onto the retina.
   5. Econtains the pigment epithelial cells that nourish photoreceptors.
2. 2Our underwater vision is poor because....

   1. Awater disperses light, making it impossible to focus.
   2. Bin water there is no longer a refractive index difference between the cornea and the surrounding media.
   3. Cwater seeps into the iris, causing temporary cloudiness.
   4. Dthe hydrostatic pressure of water changes the shape of the eyeball.
   5. EAll of the above.
3. 3Why is myopia in humans thought to be more common now than it was in ancient times?

   1. AEarly humans did no engage in the kinds of activities (e.g., reading and writing from an early age, watching television) characteristic of modern life.
   2. BMyopia was not less common, but was less recognized.
   3. CChronic exposure to fire smoke had a protective effect on the vision of early humans.
   4. DEarly humans were not exposes to the environmental toxins present in modern life.
   5. EThe vigorous exercise associated with early human lifestyles better nourished the retina.
4. 4The fovea....

   1. Ais synonymous with "funds".
   2. Bcovers approximately 40% of the retina.
   3. Clies at the center of the optic disk.
   4. Dis the only part of the retina that contains xanthophyll.
   5. Elies at the center of the macula lute.
5. 5Which of the following represents the most direct pathway for the transmission of visual information from the eye to the brain?

   1. APhotoreceptor to bipolar cell to amacrine cell to ganglion cell to brain.
   2. BPhotoreceptor to horizontal cell to ganglion cell to brain.
   3. CHorizontal cell to bipolar cell to ganglion cell to brain.
   4. DPhotoreceptor to bipolar cell to amercing cell to brain.
   5. EPhotoreceptor to bipolar cell to ganglion cell to brain.
6. 6Age-related macular degeneration, or AMD,....

   1. Acan be treated by laser-induced phototoxicity (wet AMD).
   2. BAll of the above are true.
   3. Ccan result from gradual loss of the pigment epithelium (dry AMD).
   4. Dcan be detected by means of the Amsler grid.
   5. Eis rising in incidence in the United States.
7. 7The death of retinal cells in retinitis pigmentosa is most likely....

   1. Adue to infection.
   2. Bvia apoptosis.
   3. Cdue to excessive light exposure.
   4. Ddue to environmental toxins.
   5. EAll of the above.
8. 8The two main functions of the retinal pigment epithelium are.....and.......

   1. Astructural support to maintain curvature of the retina; synthesis of rhodopsin.
   2. Bstructural support to maintain curvature of the retina; phagocytosis of shed outer segments.
   3. Cphagocytosis of shed outer segments; regeneration of the photoreceptor photopigments.
   4. Dphagocytosis of shed outer segments; synthesis of rhodopsin.
   5. Esynthesis of rhodopsin; regeneration of the photoreceptor photopigments.
9. 9Which of the following is not a component of the phototransduction signaling cascade initiated by light falling on a rod?

   1. AIncreased activity of PDE (phosphodiesterase).
   2. BA conformational change in the rhodopsin protein.
   3. CDissociation of the alpha subunit of transducin from the beta/gamma complex.
   4. DAbsorption of a photon of light by 11-cis retinal.
   5. EActivation of protein kinase A.
10. 10The primary or most proximate event that accounts for light-induces hyperpolarization of photoreceptors is....

    1. Athe gating of ion channels by released retinal monomers.
    2. Ba sudden increase in the concentration of cAMP, leading to activation of potassium channels.
    3. Ca rapid rise in the concentration of cGMP, leading to closure of Na+/Ca2+ channels.
    4. Dlight-induced photoisomerization of membrane-bound calcium channels.
    5. Ea rapid fall in the concentration of cGMP, leading to closure of Na+/Ca2+ channels.

11. 11The main reason that rods are more sensitive to light than cones is that....

    1. Athe photopigment of rods is much more sensitive to light than the photopigment used in cones.
    2. Bthe eye contains 1000 times as many rods as cones.
    3. Cthe rod transduction mechanism provides greater signal amplification.
    4. Dthe rod is sensitive to a much broader range of wavelengths.
    5. EAll of the above.
12. 12By which of the following mechanisms are rod signals transmitted in conditions of low light?

    1. ARod bipolar cells synapse upon AII amercing cells, which in turn synapse upon cone bipolar cells.
    2. BRod photoreceptors send their outputs directly to melanopsin containing ganglion cells.
    3. CRod bipolar cells of both on and off types send outputs selectively to on and off ganglion cells.
    4. DRod photoreceptors send their signals mainly through horizontal cells to the rod bipolars.
    5. ERod bipolar cells synapse upon off ganglion cells that then transmit the rod signals to the ganglion cells.
13. 13Which of the following statements about the distributions of rods and cones is true?

    1. ARods are evenly distributed across the entire retina.
    2. BBecause cones carry three different color channels, there are three times as many cones as rods.
    3. CThe density of cones is 200-fold higher in the fovea than in the most eccentric retinal regions.
    4. DThe density of rods is highest in the far periphery of the retina.
    5. ERods outnumber cones by 100 to , which explains the greater sensitivity of rods in low light.
14. 14Which of the following statements about color vision is false?

    1. ABecause there are several different color types of cones, they are sensitive to dimmer illumination levels than is the population of rods.
    2. BCones (in humans) come in three different "colors": blue, green, and red (or short, medium, and long wavelength).
    3. CDifferent wavelengths of light produce different patterns of activity in the cone population as a whole.
    4. DInformation from specific color cones can be selectively relayed to specific regions of a retinal ganglion cell's receptive field.
    5. EAll of the above are true, none is false.
15. 15The retinex theory of color information processing....

    1. Ais based on the distribution of different color cones in the retina.
    2. Bwas confirmed by voltage-dye mapping experiments in monkey cortex.
    3. Csuccessfully predicts how different forms of color-blindness will affect color perception.
    4. Dwas proposed by the artist Piet Mondrian.
    5. Emakes use of a series of ratiometric equations that integrate spectral features of the visual scene.
16. 16Which of the following statements about the conveyance of luminance signals by bipolar cells is false?

    1. AOff-bipolar cells hyperpolarize in response to light.
    2. BGlutamate causes on-bipolar cells to hyperpolarize.
    3. CBipolar cells do not have direct contacts with HCs and so are unaffected by HC activity.
    4. DGlutamate causes off-bipolar to depolarize.
    5. EOn-bipolar cells depolarize in response to light.
17. 17Which of the following statements about center-surround receptive fields in the retina is false?

    1. ACells that are excited by light in their center are inhibited by light in their surround.
    2. BThe spatial extent to which a cell can be influenced by light never extends beyond he physical extent of its dendritic field.
    3. CThe best stimulus for an on-center cell is light in its center and darkness in its surround.
    4. DThe surround portion of the receptive field is typically an annulus (or donut-shaped ring) that surrounds the circular center.
    5. ECells that are inhibited by light in their center are excited by light in their surround.
18. 18Which of the following best describes the response of an off-center ganglion cell sitting on or near an edge (dark on one side, light on the other)?

    1. AThe cell would respond most strongly to this stimulus with its off-center sitting on the dark side of the border and just barely touching the border.
    2. BThe cell would fire most strongly if the edge ran through the exact center of the cell.
    3. CThis stimulus, if optimally aligned, would evoke the cell's strongest possible firing response.
    4. DIllumination of the entire receptive field would provide a purely inhibitory signal to the cell.
    5. EThe cell would fire most strongly with its entire receptive field on the dark side of the border.
19. 19The illusion produced in Box 11F(B), where dark rectangles are placed within a pattern of light and dark bars, is best explained by which of the following?

    1. ALight scattering between adjacent photoreceptors.
    2. BAn inability to spatially resolve the intersections of the white bars.
    3. CThat photic information is conveyed only by graded electrical responses.
    4. DThat brightness percepts are generated on a statistical basis as a means of contending with the inherent ambiguity of luminance.
    5. EAll of the above are equally valid explanations.
20. 20Which of the following statements about the retina's operation across different levels of ambient light is true?

    1. AFor a given level of ambient light, an on-center ganglion cell responds proportionately to a small spot of light over an intensity range of about one log unit.
    2. BVia adaptational mechanisms, on-center ganglion cells can dynamically encode brightness levels in their on-center over a range of 6 log units of ambient light levels.
    3. CGanglion cells generally do not report absolute light intensities, but rather encode relative intensity differences between center and surround.
    4. DInteractions within the outer plexiform layer play an important role in modulating the photic sensitivity of ganglion cells.
    5. EAll of the above.

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BIO 465 Quiz on BIO 465 - CH 11, created by Olivia Feagles on 07/04/2015.

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