Compare and contrast the infection of a bacterial cell by a lytic bacteriophage with the infection of an animal cell by a retrovirus.

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.

What were the main components of earth’s earliest atmosphere? oxygen and ammonia hydrogen and helium oxygen and nitrogen hydrogen and nitrogen

What percentage of light hits earth's surface directly?