Pitch: the use of notes in voice range. Speak in a voice range that is comfortable and move up or down Pause: Give you time to catch your breath and the audience time to collect your ideas. Articulation and Pronunciation: Articulation is the art of expressing words distinctly. Pronunciation is the ability to say words correctly. Length: Length of your presentation is crucial.
Enzyme. Photo by: fotohunter. An enzyme is a biological catalyst. A catalyst is a chemical compound that speeds up the rate of some chemical reaction. When that chemical reaction occurs in a living organism, the catalyst is known as an enzyme.hemical reaction: Any change in which at least one new substance is formed. Lock-and-key model: One of the ways in which enzymes bring about chemical reactions. Product: A compound that is formed as the result of a chemical reaction.
The role of the enzyme is to reduce the activation energy, by bringing specific molecules together, rather than relying on random collisions) Action on specific Substrates. Enzymes are substrate specific, meaning only one particular substrate molecule can work with one particular enzyme. This is due to the reciprocally shaped active site. Since the enzyme is never chemically alter by a reaction, it can be reused in subsequent reactions â enzyme controlled reactions are always reversible.