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Why does passive transport require no energy?

Passive transport does not require energy. This is movement of molecules down a concentration gradient. In order to maintain equilibrium, it goes from high to low concentration. Active transport requires ATP to pump molecules up the concentration gradient.

Does passive transport require the cell to use energy?

The simplest forms of transport across a membrane are passive. Passive transport does not require the cell to expend any energy and involves a substance diffusing down its concentration gradient across a membrane.

How does passive transport move molecules across the membrane?

One example of passive transport is diffusion, when molecules move from an area of high concentration (large amount) to an area of low concentration (low amount). In simple diffusion, molecules that are small and uncharged can freely diffuse across a cell membrane. They simply flow through the cell membrane.

Does a cell use passive transport or active transplant to move molecules?

While active transport requires energy and work, passive transport does not. There are several different types of this easy movement of molecules. It could be as simple as molecules moving freely such as osmosis or diffusion.

Do aquaporins use facilitated diffusion?

Water can pass through biological membranes via two pathways: simple diffusion through the lipid bilayer, or water-selective facilitated diffusion through aquaporins (AQPs).

Are aquaporins always open?

Although many aquaporins function as always-open channels, a subgroup of aquaporins, particularly in plants have evolved a sophisticated molecular mechanism through which the channel can be closed in response to harsh conditions of the environment, under which exchange of water can be harmful for the organism.

Why do aquaporins speed up osmosis?

The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis. If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell.

Can osmosis happen without aquaporins?

Osmosis does occur through permeable membranes, but large, bulk flow of water can be mediated by protein channels called aquaporins.