36:55 Why is it important to know a person's rhesus factor before a blood transfusion? A patient who is Rh+ can receive only Rh– blood. A patient who is Rh– can receive only Rh+ blood. A patient who is Rh+ can receive only Rh+ blood. A patient who is Rh– can receive only Rh– blood.

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 does not describe a physical property of iron? a iron is silvery-white or gray in color. b iron has a boiling point of about 3,000°c. c iron is a magnetic element . d iron and sulfur react to form iron sulfide.

Which of the following is a testable hypotheses?