Question

If a single-celled alga is placed in an environment with limited light and low oxygen, what would most likely happen to its ability to cycle matter and energy?





A.
Photosynthesis would increase, and respiration would remain unchanged

B.
Photosynthesis would decrease, reducing glucose production and limiting respiration

C.
Respiration would increase to compensate for reduced photosynthesis.

D.
Photosynthesis and respiration would both increase due to stress.

Answer 1

B. Photosynthesis would decrease, reducing glucose production and limiting respiration.

Limited light lowers the alga’s photosynthetic rate so less glucose (and O2) is produced. Low O2 also constrains aerobic respiration, so overall cycling of matter and energy is reduced (the cell might only shift partially to less-efficient anaerobic pathways).