Enzymes are consumed in chemical reactions and must therefore be replenished.

The crust of earth may a- continets and ocean floors. b-continents only. c-layers of sedimentary rocks and continents. d-all of the above

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a.the mitochondria b.the nucleus c.the vacuoles d.the endoplasmic reticulum

Which of the following represents the ester functional group? a. -coo- b. -cho c. -cooh d. c=o