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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 statement is true about the cell theory? a) it is well-supported by evidence. b) it is unchangeable and permanent.

92 sathe best for the question 11. most animals and plants reproduce sexually. this means that dna is passed down to new organisms from two parental organisms. which of the following is a key advantage of sexual reproduction?