How might climate change affect animal migration patterns?

If a set of instructions that determines all of the charactersitics of an organism is comparedto a book,and a chromosme is compared to chaper in the book,then what might be compared to a paragraph in the book?

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.

Which type of neuroglia is found outside of the brain?