When did the first humans appear on earth

Look at the picture below . what does this picture represent ?

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

When is your respiration rate likely to change? a. when your intestines are digesting b. when your cells have too much glucose c. when your cells need more oxygen d. when your liver is working after a meal