Which of the following was one of the first instruments that prehistoric people probably used?
a. lyres
b. tambourines
c. guitars
d. voices

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.

How do living things obtain phosphorus

What is one way intensive agriculture can contribute to climate change? a. tree loss to agriculture increases earth's albedo b. livestock manure absorbs greenhouse gases c. large herds of livestock release greenhouse gases d. fewer trees are available to replenish petroleum stores appex