Question

which statement best describes passive transport? *
it uses atp to move substances into the cell.
it requires energy to move molecules against their concentration gradient.
it moves only water molecules across the plasma membrane.
it moves molecules from high to low concentration without using energy.
some cells allow water to pass through their membranes much faster than simple diffusion would allow. which structure helps speed up the movement of water across the plasma membrane?

Explanation:

Passive transport is a type of cellular transport that does not require energy (ATP) and moves substances down their concentration gradient (from high to low concentration). Active transport uses ATP and moves substances against their concentration gradient. Osmosis is the diffusion of water, but passive - transport is not limited to water movement only. Aquaporins are channel proteins that facilitate the rapid movement of water across the plasma membrane, allowing water to pass through much faster than by simple diffusion.

Answer:

1. It moves molecules from high to low concentration without using energy.
2. Aquaporins.