Answers and Explanations:
14. Catalysts; decreasing; activation.
In science, catalysts are known to speed up a reaction. Every reaction starts with activation energy, but the smaller the activation energy, the faster the reaction will run. That's why catalysts decrease that energy.
16. Products
Chemical reactions turn reactants into products.
17. Active site
The substrate binds to the enzyme at an place called the active site, where the shape of the site matches the shape of the substrate. Usually this model can be called the lock-and-key model, or more recently, the induced fit model.
19. Semi-permeability
Semi-permeability basically means that only certain things can enter the cell. For example, nutrients can come in while waste can be let out. However, harmful substances will be recognized by the cell, so they can't come in thanks to the semi-permeable membrane.
Hope this helps!