Answer:
c
Explanation:
etc uses oxygen
photosynthesis uses carbon dioxide
A. they are drugs or hormones used to prevent osteoporosis
The layers on the top may be younger, while the bottom layers may be much older.
Carbon dioxide (CO2) is formed from one carbon atom bonded to two oxygen atoms. Therefore, carbon dioxide is a compound!
The answer is: the amount of the saliva samples must stay consistent while the amount of starch must vary.
The amount of the saliva samples must stay consistent because amylase, present in the saliva, is the independent variable which affects the dependent variable - the amount of starch. So, amylase will do its job while remaining surface area of the starch will depend on the starting amount of the starch.
