The cytoplasm of animal cells has a concentration of potassium ions (k ) as much as 20 times higher than the concentration outside the cell. how do cells move potassium ions against a concentration gradient, from a lower concentration to a higher one?
a. facilitated diffusion
b. active transport
c. osmosis
d. diffusion

Energy derived from hot rocks and fluids beneath the earth’s surface is

The phlogiston theory in the 17th century attempted to explain burning. the theory stated that combustable objects contained a material called phlogiston, a substance without mass, color, odor, etc. after objects burned, the objects were dephlogistonated and were then in their true form. the phlogiston theory was accepted until the 18th century, when lavoisier proved that combustion requires a gas that has mass. phlogiston is considered a) to be scientific knowledge b) not to be scientific knowledge c) to be proven by scientific method d) to be accepted in the modern scientific community

Explain how the political influence of african americans leaders became weaker.