True or false 3-5?
the human heart is about the size of a fist true or false ?
enzymes to digest food true or false ?
red blood cells make up almost half of the blood cells in the body true or false ?

Explanation:

The human heart IS about the size of the fist.

Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. They are vital for life and serve a wide range of important functions in the body, such as aiding in digestion and metabolism.

Red blood cells DO make up almost half of the blood cells in the body.

p

explanation:

where is the scientific experiment?