The shells of clams and oysters collect on the seafloor. over time they form a rock. what type of rock is it

Look at the punnett square for an x-linked recessive disease. is it possible for a female offspring to have the disease?

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.

What is the problem in this article? what solution does the article propose?