An organelle that releases energy for metabolic activity in a nerve cell is the what

What adaptation is apparent in the bodies of the three tortoise species shown in figure 16-2

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 these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine