A student measured the amount of oxygen and carbon dioxide dissolved in an aquarium containing an aquatic plant and a snail. Why
did the amount of dissolved oxygen decrease when the aquarium was kept in the dark for 10 hours?A.
Because photosynthesis could not occur
B.
Because the plant died
C.
Because the snail died
D.
Because cellular respiration could not occur
The answer is A. Putting the aquarium in the dark means that
the aquatic plants will not be able to photosynthesize. The process of photosynthesis produces oxygen
as a by-product. The oxygen is used by the fishes in respiration and release
carbon dioxide. The carbon dioxide is used by the aquatic plants in photosynthesis.
