Which statement best compares the aorta and the pulmonary vein? O Both structures control the flow of blood.
O Both structures are involved in transporting oxygenated blood.
O Both structures separate the left and right atrium.
O Both structures carry plasma back into general circulation.

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

Which macromolecule catalyzes chemical reactions this be considered enzyme chemical reactions thus he considering enzymes