A chemical reaction in a living cell occurs in the presence of a specific protein molecule. The concentration of this protein molecule temían the same before and after the reaction. This protein molecule is most likely - a coenzyme
- a substrate
- an enzyme
-an acid

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Which of the following is the best definition of aerobic respiration? o a. the cellular process that releases energy by breaking down glucose o b. physical activity that involves the repeated motion of large muscle groups o c. physical activity that increases heart rate and breathing rate o d. the cellular process that converts solar energy to chemical energy

Select all that apply. why are common names not a good reference to a species? common names can be in different languages common names vary with location common names vary with culture common names vary with species color