Genetic and environmental factors affect which traits are passed on from parent to offspring over generations and how they are passed on. Favorable traits for a given environment are passed on from parent to offspring. Unfavorable traits are selected against and inherited less frequently over time because they do not promote survival and reproduction.

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.

Identify the composition of oceanic and continental crystal rocks.in a model of earth’s interior,where would these rocks appear?

Which was most likely an effect on society that resulted from improvements in blood handling during world war i and world war ii?