Pituitary gland.
When you feel stress, the pituitary gland, at the base of the brain, increases its production of the hormone ACTH. This hormone tells the adrenal glands, found at the top of your kidneys, to increase their production of hormones. These stress hormones help you to concentrate, speed your reaction time, and boost your strength. Your hypothalamus also helps your body respond to stress.
Other types of enzymes can put atoms and molecules together. Breaking molecules apart and putting molecules together is what enzymes do, and there is a specific enzyme for each chemical reaction needed to make the cell work properly.
https://science.howstuffworks.com/life/cellular-microscopic/cell2.htm
Studies the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor.
