Nuclear fusion reactions occur when hydrogen atoms combine to form helium atoms. As this happens, great amounts of light and heat energy are given off. Which celestial body, most likely is a place where nuclear fusion occurs? A. Comet
B. Star
C. Asteroid
D. Meteor

1. an enzyme is considered a(n) because it speeds up a chemical reaction without being used up.2. in a catalyzed reaction, a reactant is often called a(n) . an enzyme is specific because the shape of its matches only particular reactants.4. an enzyme speeds up reactions by lowering the . the between an active site and its substrate often strains bonds and the reaction proceed.6. a( , which is often a vitamin, binds to an enzyme and plays a role in catalysis.7. high temperatures or changes in ph can an enzyme, causing it to lose its shape and biological activity.