What are the ways that carbon enters back into the atmosphere?

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.

Crossing over and independent assortment are important activities that occur during meiosis. what is the significance of these activities

This is the main structural axis of the plant that supports leaves, flowers and fruits; transports fluids; stores nutrients and produces new tissue.