MCAT Social and Behavioral Sciences : Visual Receptors

Study concepts, example questions & explanations for MCAT Social and Behavioral Sciences

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Example Questions

Example Question #14 : Vision

Which photoreceptor cell is primarily responsible for detecting nuances in color?

Possible Answers:

Rods

Cones

Photosensitive retinal ganglion cells

Cones and rods

Correct answer:

Cones

Explanation:

Cones are the primary photoreceptor cells responsible for transmitting information about color. They are the only photoreceptor cell type that is capable of differentiating between colors. Rod cells are not capable of color vision and primarily transmit information in regards to contrast. They are most active in very low light, while cone cells are most active in levels of high light. This is why it is difficult to perceive color at very low light levels. Photosensitive retinal ganglion cells do not transmit visual information to the brain - rather, they are involved in physiological processes such as pupillary reflex and circadian rhythms. 

Example Question #15 : Vision

Which of the following is the term for the light-sensitive cells of the retina?

Possible Answers:

Photophilic cells

Aural cells of the retina

Photoreceptor cells

Photogenic receptor cells

Correct answer:

Photoreceptor cells

Explanation:

The light sensitive cells of the retina are called "photoreceptor cells." This is a group of cells with various functions regarding the transmission of information about brightness, color, and contrast. None of the other structures listed are cell types of the eye.

Example Question #16 : Vision

Which of the following photoreceptor cell is most sensitive to light?

Possible Answers:

Cones

Photosensitive retinal ganglion cells and cones

Photosensitive retinal ganglion cells

Rods

Correct answer:

Rods

Explanation:

“Rods” are incredibly sensitive to light, and can be triggered by a single photon. These cells are the primary photoreceptor cells active at very low light. The activation of cone cells requires significantly larger amounts of photostimulation; therefore, they function primarily in interpreting visual information in bright light. Photosensitive retinal ganglion cells, a group of cells that make up a very small percentage of overall photoreceptor cells, are less sensitive to photons and have a slower response time than either rods or cones.

Example Question #17 : Vision

Which of the following is not a type of photoreceptor cell?

Possible Answers:

Photosensitive retinal ganglion cells 

Rods

Cones

None of these

Correct answer:

None of these

Explanation:

There are three types of photoreceptor cells in the retina: “rods,” “cones,” and “photosensitive retinal ganglion cells.” While rods and cones directly communicate information about sight (e.g. contrast, brightness, and color), photosensitive retinal ganglion cells do not directly communicate visual information to the brain. Rather, they are involved in the pupillary reflex.

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