Match the names and descriptions to the correct phase of a star's life cycle.

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.

Astudent drew the following flowchart to show the movement of nutrients. soil → roots → plants →? where does nitrogen go next? a. directly into nearby animals as nutrition b. directly into aquifers through condensation c. directly into the air through evaporation d. directly into nearby plants during fixation

Identify the various levels of atmosphere. troposphere mesosphere exosphere stratosphere thermosphere