Which statement best explains why carbon is present in so many kinds of molecules? it is abundant on earth. it can form four covalent bonds. it has valence electrons. it can become an ion.

People who exercise for an hour may have lower cholesterol levels. is that a statement? a law? or a hypothesis?

1. environmental factors, such as ph and temperature, can affect the function of an enzyme. a. true b. false 2. which of the following is an organic molecules (ex. vitamins) that an enzyme? a. coenzyme b. product c. active site d. substrate 3. how do enzymes effect the speed of a chemical reaction? a. they speed it up b. they slow it down c. they have no effect on the speed of a reaction 4. during a chemical reaction, an enzyme is used up so that it can only be used one time. a. true b. false 5. which of the following results from a chemical reaction that is catalyzed by an enzymes? a. active site b. product c. substrate d. coenzyme

The response is the basis for vaccination. primary secondary tertiary none of the above