Select the elements that have 4 valence electrons. hydrogen (H)
krypton (Kr)
strontium (Sr)
carbon (C)
oxygen (O)
tin (Sn)

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.

Which best describes carbon dioxide’s path out of the body

In an hydrogen ion pump the energy is used to join small molecules together to make larger ones which factor most likely has the greatest effect on the number of molecules mitochondria can produce