Unit 2 Biochemistry: Certain marine algae are able to live in low light,
at depths of more than 100 m. These algae appear
almost black deep under water, but usually appear
red when brought to the surface. T/I
(a) Would you expect these species to contain more
or less chlorophyll than green algae? Why?
(b) Would you expect these species to perform
photosynthesis more efficiently under a green
light source or a red light source? Explain your
reasoning.
(c) Things tend to look bluish underwater because
water absorbs red light more effectively than blue
light. How might this fact help account for the
characteristics of the deep-water species of algae?

Question

Certain marine algae are able to live in low light,
at depths of more than 100 m. These algae appear
almost black deep under water, but usually appear
red when brought to the surface. T/I
(a) Would you expect these species to contain more
or less chlorophyll than green algae? Why?
(b) Would you expect these species to perform
photosynthesis more efficiently under a green
light source or a red light source? Explain your
reasoning.
(c) Things tend to look bluish underwater because
water absorbs red light more effectively than blue
light. How might this fact help account for the
characteristics of the deep-water species of algae?

fahr dat · Accepted Answer

(a) Algae living in low-light depths have less green chlorophyll and more red pigments, like carotenoids, making them appear red when brought to the surface.

(b) These algae likely photosynthesize more efficiently under green light than red light because red pigments reflect red light and absorb green light.

(c) Deep-water species have adapted to absorb light at the opposite end of the spectrum since very little red light penetrates deep water. When at depth, they reflect red light, but their environment lacks significant red light.

Unit 2 Biochemistry

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