Which is false? a. Enzymes are very specific for certain substrates. b. Enzymes are used up in chemical reactions. c. An enzyme binds to its substrate at the enzyme's active site. d. Enzymes emerge unchanged from the reactions they catalyze.

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

Which would happen if more forests were cut down? a. the nitrogen cycle would be stopped b. nitrogen would be fixed by bacteria more quickly c. the amount of co2 in the atmosphere would increase d. fossil fuels would build up in the soil c the amount of co2 in the atmosphere would increase

Which of the following is the best definition of a eukaryota? a. a one-celled organism that does not have a membrane-bound nucleus b. a one-celled organism that does not have a cell wall c. an organism whose cells each contain a membrane-bound nucleus d. an organism whose cells each have a cell wall