Ch 10 Vision: The Eye test bank ?s

Question 1

1. Which eye structure is paired with an appropriate characteristic?
   a. Cornea: contains neurons that are sensitive to light and transmit visual signals
   b. Aqueous humor: fills the space between the back of the lens and the retina
   c. Pupil: separates and protects the eye from the external environment
   d. Retina: produces melanin and capillaries to nourish photoreceptors
   e. Ciliary body: produces fluid to fill the front of the eye

Answer 1

Answer: e
Textbook Reference: Anatomy of the Eye
Bloom’s Level: 1. Remembering

Question 2

2. An optometrist discovers that her patient has poor drainage of his aqueous humor, and
   a test confirms high intraocular pressure. These symptoms suggest which condition?
   a. Presbyopia
   b. Emmetropia
   c. Cataracts
   d. Glaucoma
   e. Macular degeneration

Answer 2

Answer: d
Textbook Reference: Anatomy of the Eye
Bloom’s Level: 3. Applying

Question 3

3. On its way to the retina, light passes through tissues and fluids in which order?
   a. Cornea, aqueous humor, lens, vitreous humor, retina
   b. Sclera, aqueous humor, pupil, lens, vitreous humor, retina
   c. Cornea, vitreous humor, lens, aqueous humor, retina
   d. Sclera, vitreous humor, lens, aqueous humor, retina
   e. Cornea, aqueous humor, pupil, vitreous humor, retina

Answer 3

Answer: a
Textbook Reference: Anatomy of the Eye
Bloom’s Level: 4. Analyzing

Question 4

4. During accommodation, the shape of the _______ is changed by the _______ in order
   to see objects accurately at varying distances.
   a. lens; zonule fibers
   b. lens; ciliary muscle
   c. pupil; ciliary muscle

d. pupil; zonule fibers
e. iris; zonule fibers

Answer 4

Answer: b
Textbook Reference: Image Formation on the Retina
Bloom’s Level: 2. Understanding

Question 5

5. Which statement about the optic disc is false?
   a. It is a region without photoreceptors.
   b. It is where retinal nerves leave the eye to reach targets in the thalamus and midbrain.
   c. It contains a small depression known as the fovea.
   d. It can be an indicator for intracranial pressure.
   e. It creates a blind spot.

Answer 5

Answer: c
Textbook Reference: The Retinal Surface
Bloom’s Level: 1. Remembering

Question 6

6. A 68-year-old man notices that the boxes of his crossword puzzle look wavy and
   blurry for the word he is working on, but the boxes in the periphery of his focus remain
   clear. This symptom suggests that the man has which condition?
   a. Presbyopia
   b. Emmetropia
   c. Cataracts
   d. Glaucoma
   e. Macular degeneration

Answer 6

Answer: e
Textbook Reference: The Retinal Surface
Bloom’s Level: 4. Analyzing

Question 7

7. What is the most direct path that light information travels on its way to the optic nerve?
   a. Photoreceptor cell; bipolar cell; ganglion cell; optic nerve
   b. Photoreceptor cell; ganglion cell; bipolar cell; optic nerve
   c. Bipolar cell; photoreceptor cell; ganglion cell; optic nerve
   d. Bipolar cell; ganglion cell; photoreceptor cell; optic nerve
   e. Ganglion cell; photoreceptor cell; bipolar cell; optic nerve

Answer 7

Answer: a
Textbook Reference: Retinal Circuitry
Bloom’s Level: 3. Applying

Question 8

8.Which of the following statements about the location photoreceptors in the outermost
layer of the retina is true.
a. This placement allows light to stimulate the photoreceptors via the most direct path.
b. The proximity to the pigment epithelium allows nourishment for the photoreceptor
cells and recycling of photopigment.
c. This placement allows more synapses to be formed between amacrine cells and
ganglion cells.
d. The proximity to the pigment epithelium determines if a photoreceptor cell
differentiates into a rod or a cone.
e. This placement allows a light stimulus to be filtered when it travels through the other
layers of the retina to reach the outermost layer.

Answer 8

Answer: b
Textbook Reference: The Pigment Epithelium
Bloom’s Level: 2. Understanding

Question 9

9. Applying a drug that increases cGMP levels in photoreceptors would cause which effect on a photoreceptor’s response to a photon of light?
   a. An intensified depolarization from normal
   b. An attenuated depolarization from normal
   c. An intensified hyperpolarization from normal
   d. An attenuated hyperpolarization from normal
   e. There would be no effect

Answer 9

Answer: d
Textbook Reference: Phototransduction
Bloom’s Level: 4. Analyzing

Question 10

10. Which mechanism decreases sensitivity in a photoreceptor as levels of illumination
    increase?
    a. The retinoid cycle
    b. Accommodation
    c. Transducin
    d. Rhodopsin
    e. Light adaptation

Answer 10

Answer: e
Textbook Reference: Phototransduction
Bloom’s Level: 1. Remembering

Question 11

11. If a person had a mutation in the gene that codes for interphotoreceptor retinoid
    binding protein, what would be the most likely downstream effects?
    a. Arrestin would not be able to bind to rhodopsin.
    b. Opsin would not be able to activate the intracellular messenger transducin.
    c. Retinal could not be transported to and from the outer segment for the retinoid cycle.
    d. The conformational change from cis-retinal to trans-retinal could not take place during
    photoisomerization.
    e. PDE would not hydrolyze cGMP to reduce its concentration.

Answer 11

Answer: c
Textbook Reference: Phototransduction
Bloom’s Level: 4. Analyzing

Question 12

12. Mesopic vision is most likely to occur in which of the the following scenarios?
    a. Sitting on a sunny beach
    b. Standing in a dark closet
    c. Reading in a park on a cloudy afternoon
    d. Shopping inside a department store
    e. Walking outdoors at the break of dawn

Answer 12

Answer: e
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 3. Applying

Question 13

13. The reason that rods do not contribute to photopic vision is
    a. they are not being stimulated.
    b. their response is saturated.
    c. all of their membrane channels are open.
    d. they are not responsible for color vision.
    e. they have low resolution.

Answer 13

Answer: b
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 2. Understanding

Question 14

14. Which of the following correctly matches rods and cones with their properties?
    a. Rods: high spatial resolution; cones: color vision
    b. Rods: high sensitivity to light; cones: high spatial resolution
    c. Rods: color vision; cones: low spatial resolution
    d. Rods: high sensitivity to light; cones: low spatial resolution
    e. Rods: low sensitivity to light; cones: color vision

Answer 14

Answer: b
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 4. Analyzing

Question 15

15. Which statement about rod and cone convergence in the retina is true?
    a. Many cones converge onto one cone bipolar cell.
    b. Convergence makes the cone system a better detector of light.
    c. Convergence increases the spatial resolution of rods.
    d. The one-to-one relationship of rods to bipolar and ganglion cells increases acuity.
    e. Convergence allows rods to pool signals, generating larger responses in bipolar cells.

Answer 15

Answer: e
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 2. Understanding

Question 16

16. What accounts for the fact that rods do not contribute to vision in daylight?
    a. Rods cannot be stimulated by photons in daylight.
    b. The occipital lobe ignores rod signaling in daylight.
    c. All membrane channels are closed due to saturation in daylight.
    d. The retinoid cycle in rods stops in daylight.
    e. cGMP is quickly depleted in daylight.

Answer 16

Answer: c
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 2. Understanding

Question 17

17. Which symptom would you expect a person with damage to the fovea to experience?
    a. Total blindness
    b. Poor peripheral vision
    c. Difficulty seeing large objects
    d. Trouble reading
    e. Increased sensitivity to light

Answer 17

Answer: d
Textbook Reference: Anatomical Distribution of Rods and Cones
Bloom’s Level: 3. Applying

Question 18

18. Which feature is responsible for the superior acuity of the fovea?
    a. Lack of retinal blood vessels
    b. Higher density of ganglion cells
    c. Increased concentration of rods
    d. Presence of the inner nuclear layer
    e. Maximum photon scattering before reaching the photoreceptors

Answer 18

Answer: a
Textbook Reference: Anatomical Distribution of Rods and Cones
Bloom’s Level: 2. Understanding

Question 19

19. Which property best differentiates the types of cones?
    a. Their location in the retina
    b. The number of synapses on bipolar cells
    c. The photopigments they contain
    d. Their overall ratio to other types of cones
    e. Their shape and processes

Answer 19

Answer: c
Textbook Reference: Cones and Color Vision
Bloom’s Level: 1. Remembering

Question 20

20. A genetically engineered macaque has had the gene that codes for M pigment
    knocked out. Which vision impairment should the knockout macaque have?
    a. Blue-yellow color blindness
    b. Anomalous trichromat
    c. Protanopia
    d. Deuteranopia
    e. Complete loss of color vision

Answer 20

Answer: d
Textbook Reference: Cones and Color Vision
Bloom’s Level: 3. Applying

Question 21

21. A man with dichromatic vision would have the most trouble with which task?
    a. Determining when a red light turns green
    b. Differentiating his chess pieces from his opponent’s
    c. Reading a novel
    d. Seeing stars in the night sky
    e. Adjusting to bright lights in a store

Answer 21

Answer: a
Textbook Reference: Cones and Color Vision
Bloom’s Level: 3. Applying

Question 22

22. Why are males more likely than females to have red–green color deficiencies?
    a. Sex differences in their mitochondrial genes.
    b. The red and green pigment genes are located on the X chromosome.
    c. The red and green pigment genes are located on chromosome 7.
    d. Normal trichromats have one gene for red pigments.
    e. Normal trichromats have a varying number of genes for green pigments.

Answer 22

Answer: b
Textbook Reference: Cones and Color Vision
Bloom’s Level: 2. Understanding

Question 23

23. How would an OFF-center neuron’s firing rate change when a light was turned on,
    turned off, and then turned on again?
    a. Increase, increase, decrease
    b. Increase, decrease, increase
    c. Decrease, increase, decrease
    d. Decrease, increase, increase
    e. Decrease, decrease, increase

Answer 23

Answer: c
Textbook Reference: Retinal Circuits for Light and Dark
Bloom’s Level: 2. Understanding

Question 24

24. A photoreceptor cell is exposed to a flash of light. How does the membrane potential
    of this cell and its corresponding ON-center bipolar and ganglion cells change?
    a. Hyperpolarize, hyperpolarize, depolarize
    b. Depolarize, hyperpolarize, depolarize
    c. Hyperpolarize, depolarize, hyperpolarize
    d. Depolarize, hyperpolarize, hyperpolarize
    e. Hyperpolarize, depolarize, depolarize

Answer 24

Answer: e
Textbook Reference: Retinal Circuits for Light and Dark
Bloom’s Level: 3. Applying

Question 25

25. What is the major anatomical difference between ON-center and OFF-center bipolar
    cells that explains their selective response to light increments?
    a. They release different neurotransmitters onto ganglion cells.
    b. They have different glutamate receptor types.
    c. OFF-center cells have larger dendritic fields.
    d. They have different GABA receptor types.
    e. ON-center cells have larger cell bodies.

Answer 25

Answer: b
Textbook Reference: Retinal Circuits for Light and Dark
Bloom’s Level: 2. Understanding

Question 26

26. A ganglion cell’s firing rate is proportional to what property of light?
    a. Wavelength
    b. Period
    c. Intensity
    d. Frequency
    e. Color

Answer 26

Answer: c
Textbook Reference: The Adjustable Operating Range of Retinal Ganglion Cells
Bloom’s Level: 2. Understanding

Question 27

27. How would the firing of an ON-center ganglion cell respond as a light moved from
    the edge of the receptor field to the center of the receptive field?
    a. It would increase.
    b. It would decrease.
    c. It would increase then decrease.
    d. It would decrease then increase.
    e. There would be no change.

Answer 27

Answer: a
Textbook Reference: Luminance Contrast and Receptive Field Surrounds
Bloom’s Level: 3. Applying

Question 28

28. In which scenario would an ON-center ganglion cell fire the most robustly?
    a. A small light shining in the center of the receptive field
    b. A light filling the center of the receptive field
    c. A light filling the center and surround of the receptive field
    d. A light filling only the surround of the receptor field
    e. No light shining in the receptor field

Answer 28

Answer: b
Textbook Reference: Luminance Contrast and Receptive Field Surrounds
Bloom’s Level: 3. Applying

Question 29

29. Which cell type is thought to be responsible for the antagonistic surround of ganglion
    cells?
    a. Photoreceptor
    b. Bipolar
    c. Ganglion
    d. Horizontal
    e. Amacrine

Answer 29

Answer: d
Textbook Reference: Luminance Contrast and Receptive Field Surrounds
Bloom’s Level: 1. Remembering

Question 30

30. Due to a genetic modification, a mouse has no horizontal cells in its retinas. What
    impact will this have on the mouse’s vision?
    a. Dichromatic color blindness
    b. Inability to detect light
    c. Reduced ability to determine relative stimulus intensity
    d. Increased ability to detect luminance
    e. There will be no effect on the mouse’s vision.

Answer 30

Answer: c
Textbook Reference: Luminance Contrast and Receptive Field Surrounds
Bloom’s Level: 3. Applying

Question 31

1. Are there more rods or cones in the retina? In the fovea?

Answer 31

Answer: There are many more rods (about 90 million) than cones (about 4.5 million) in
the retina. However, cone density increases dramatically in the fovea, with the foveola
being completely rod-free.
Textbook Reference: The Retinal Surface
Bloom’s Level: 1. Remembering

Question 32

2. Describe the five types of retinal neurons. Which cells are in the outer nuclear layer?

Answer 32

Answer: Photoreceptors, or rods and cones, have an outer segment adjacent to the
pigment epithelium and cell bodies in the outer nuclear layer. Photoreceptor cells synapse on bipolar cells, which in turn synapse on ganglion cells. The processes of horizontal
cells allow for lateral interactions between photoreceptors and bipolar cells. The
processes of amacrine cells are postsynaptic to bipolar cell terminals and presynaptic to
the dendrites of ganglion cells. Amacrine cells can be classified into different subclasses,
based on their function.
Textbook Reference: Retinal Circuitry
Bloom’s Level: 2. Understanding

Question 33

3. Is the retina part of the central nervous system? Explain.

Answer 33

Answer: The retina is part of the central nervous system because it is formed via
outpocketing of the diencephalon during development. The retina contains a complex
neuronal circuitry, allowing it to convert the graded electrical activity of the
photoreceptors into action potentials that travel along the axons of the optic nerve.
Textbook Reference: Retinal Circuitry
Bloom’s Level: 2. Understanding

Question 34

4. What is the role of horizontal cells?

Answer 34

Answer: Horizontal cells have cell bodies in the inner nuclear layer and processes that
laterally connect photoreceptor cells and bipolar cells. It is thought that they regulate the
amount of transmitter released from the photoreceptors to act on bipolar cells. This is
important for luminance, or the ability to detect contrast over a wide range of light
intensities.
Textbook Reference: Retinal Circuitry
Bloom’s Level: 2. Understanding

Question 35

5. What are some differences between photoreceptors and other sensory cells?

Answer 35

Answer: Photoreceptors exhibit a graded change in membrane potential in response to
light instead of action potential. They also maintain a resting membrane potential around
–40 mV, and they hyperpolarize in the presence of light.
Textbook Reference: Phototransduction
Bloom’s Level: 2. Understanding

Question 36

6. Explain the steps in phototransduction in a rod, including its resting state and what
   happens when a photon is absorbed.

Answer 36

Answer: At rest, a rod photoreceptor contains high levels of cGMP in its outer segment.
The cGMP binds to cGMP-gated cation channels, keeping them open, thus maintaining a depolarized state. When a photon is absorbed, cGMP levels decrease, cGMP dissociates from the channels, and the cGMP-gated channels close. This reduces the flow of Na + and Ca 2+ into the cell. However, K + channels remain open in the presence of light, so positive charge flows out of the cell more rapidly than it flows in, leading to hyperpolarization.
Textbook Reference: Phototransduction
Bloom’s Level: 3. Applying

Question 37

7. Why is light adaptation in the retina so important, and what does it involve?

Answer 37

Answer: Light adaptation occurs when photoreceptors decrease their sensitivity as
illumination increases. This prevents the receptors from saturating, and it extends the
range of light intensities that they can respond to.
Textbook Reference: Phototransduction
Bloom’s Level: 2. Understanding

Question 38

8. What are the advantages of animals having both rods and cones, rather than just one
   type of photoreceptor?

Answer 38

Answer: Rods are very sensitive to light and thus facilitate vision in low light. Cones have
very high spatial resolution (providing visual acuity) and different photopigments
(allowing animals to see in color). Having both rods and cones allows animals to see and
process a great variety of visual stimuli in different environments and across a broad
range of light conditions.
Textbook Reference: Functional Specialization of the Rod and Cone Systems
Bloom’s Level: 3. Applying

Question 39

9. What is the evidence that human color vision is trichromatic?

Answer 39

Answer: Studies show that any color stimulus can be duplicated by a second stimulus
composed of three superimposed light sources of short, medium, and long wavelengths
(as long as the intensity of the light sources can be independently adjusted).
Textbook Reference: Cones and Color Vision
Bloom’s Level: 2. Understanding

Question 40

10. What observations led Kuffler to define two types of retinal ganglion cells: OFF-
    center and ON-center? Explain how this receptive field organization is useful in detecting
    luminance contrast and changes in light intensity.

Answer 40

Answer: Kuffler discovered that each ganglion cell responds to stimulation in its
receptive field by increasing or decreasing its firing rate. ON-center and OFF-center cells
responded oppositely to the presence or absence of light. These receptive fields overlap in the retina, allowing for a more complex detection of contrast and changes in light
intensity.
Textbook Reference: Retinal Circuits for Light and Dark
Bloom’s Level: 3. Applying