Define Osmosis and Diffusion AND explain the difference between the two. please need help

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.

The term used to describe a disease-causing microorganism isa. virus. b. infection. c. pathogen. d. microbe. e. bacterium.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?