Which phyla includes animals with a digestive tract that has only a single opening

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

Amylase is an enzyme found in the human digestive system. why do you think it was important to keep the enzyme temperature above 37 degrees celsius (98.6 degrees f)? describe what might happen if the temperature decreased by 10 degrees celsius.

Iwanna go do something with my ideas? ?