MCAT Biology : Compound Quantification

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

Example Question #1 : Compound Quantification

The visible spectrum is typically between 390-700nm. Shorter wavelengths are responsible for the purple end of the color spectrum, while red is perceived in the eye from the longer wavelengths. -carotene is able to absorb light at a maximum value of 497nm.

-carotene is found in carrots. What would need to happen to -carotene in order for the color of carrots to become more yellow?

Possible Answers:

The -carotene must become less saturated

The number of amount of double bonds must be increased

The number of amount of conjugated double bonds must be reduced

The amount of -carotene in carrots must be reduced

Correct answer:

The number of amount of conjugated double bonds must be reduced

Explanation:

The wavelength of light absorbed by a pigment is related to the number of conjugated double bonds in the molecule. The eye will begin to perceive color when the number of conjugated double bonds in a molecule becomes around eight. At this point, the color yellow can be perceived by the eye. In order for -carotene to give carrots a more yellowish color, it must have a change in the number of conjugated double bonds so that the pigment absorbs a shorter wavelength of light. This way, it will emit complementary light with a wavelength closer to yellow on the visible spectrum.

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