What is a major difference between facilitated diffusion and active transport?
question 3 options:

active transport moves substances against the concentration gradient.

active transport uses proteins in the process.

facilitated diffusion moves molecules through the plasma membrane.

facilitated diffusion requires large amounts of energy.

Active transport moves substances against the concentration gradient

Explanation:

Facilitated diffusion moves their substances down their concentration gradient while  active transport moves substances against the concentration gradient. Facilitated diffusion is a passive process and does not require cellular energy. Active transport uses carrier proteins. Energy is used to change the shape of the carrier protein. Facilitated diffusion uses both gated channel proteins and carrier proteins in transport.

i think the answer is a.keratin is the pigment responsible for skin color.

carbon traps heat so more of it makes it hotter causing global warming. during the ice age carbon levels in the atmosphere were low so it got very cold. so the common things between them is carbon levels in the atmosphere.