Astudent 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.

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d