The membrane that surrounds a cell acts as a gateway. this the cell stay healthy. why does the cell need a gateway?
a.
cells need a way to take in and remove blood.
b.
cells need a way to take in food and waste.
c.
cells need a way to take food in and remove waste.
d.
cells need a way to move food in, but they do not have any waste.

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’s this animal (picture is tagged) and where is it most likely to live, rainforest or desert?

What are the seven economic and social goals?