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Chloroplasts contain chlorophyll and carotenoids. Chlorophyll directly absorbs light for use in photosynthesis.

Carotenoids absorb light and transfer the energy from light to chlorophyll. The efficiency of photosynthesis varies with
the wavelengths of the light that illuminates the chloroplasts. In an experiment to study the relationship between the
incoming light wavelengths and the chemical reactions of photosynthesis using a species of green algae, a researcher
labeled the COt2 supply to the algae with 14C, and the H20 with 180.
Which of the following results is expected?
O More 14C is found in the algae when it is illuminated by green light than when it is illuminated by blue-violet and red
light.
O More 180 is found in the algae when it is illuminated by green light than when it is illuminated by blue-violet and red
light
O More 14C is found in the algae when it is illuminated by blue-violet and red light than when it is illuminated by green
light.
O More 180 is found in the algae when it is illuminated by blue-violet and red light than when it is illuminated by green
light
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User FeroxTL
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Final answer:

More 14C would be incorporated into algae during photosynthesis under blue-violet and red light compared to green light because chlorophyll absorbs those wavelengths more efficiently, thus facilitating the photosynthesis process.

Step-by-step explanation:

In the context of photosynthesis and the absorption spectrum of photosynthetic pigments, it's important to note that chlorophyll, present in chloroplasts, absorbs mainly blue-violet and red wavelengths of light while reflecting green light. This is because chlorophyll a and b have absorption peaks in the blue and red parts of the spectrum, which corresponds with the wavelengths most effective at driving photosynthesis. In contrast, carotenoids absorb blue light and reflect yellow-to-orange light, complementing chlorophyll by extending the range of absorbed light wavelengths. Understanding this, we can predict that algae in the described experiment will perform better photosynthesis under blue-violet and red light than under green light, since green light is mostly reflected and not absorbed.

Hence, the correct expectation is that more 14C is found in the algae when it is illuminated by blue-violet and red light than when it is illuminated by green light. This is because the absorbed light energy is used to convert CO2 and water into glucose, with CO2 becoming incorporated into the synthesized organic compounds which is then detectable through the labeled 14C.

User Jon Rein
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