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this means that it allows some materials, but not all, to cross it, or permeate it.
Materials cross the plasma membrane through processes such as simple diffusion, facilitated diffusion, and active transport. These processes involve the movement of substances across the lipid bilayer of the membrane with the help of transport proteins or by utilizing energy to move against a concentration gradient.
What you are considering when you are referring to how easily materials can pass through a membrane is how permeable the cell wall or membrane is.
It is the ability of the membrane to allow ions and/or particles to cross.
Intracellular
A selectively permeable membrane allows SOME but not ALL materials to cross.
A membrane that lets all materials cross is permeable. A membrane that lets nothing cross is impermeable.
Some materials cross the cell membrane by diffusion. Some cross through channels. Some bind to receptors and are actively transported.
The past tense of "cross" is "crossed."
The past tense of the word "cross" is "crossed."
this means that it allows some materials, but not all, to cross it, or permeate it.
The word crossed in the past tense of the verb to cross. He crossed the street.
Materials cross the plasma membrane through processes such as simple diffusion, facilitated diffusion, and active transport. These processes involve the movement of substances across the lipid bilayer of the membrane with the help of transport proteins or by utilizing energy to move against a concentration gradient.
Semi-permeable membrane
Crossed
The verb in the sentence 'he crossed the bridge' is crossed. The word 'crossed' comes from the verb 'to cross'.
Cells have methods other than diffusion/osmosis to move materials across the cell membrane, most of which involve membrane proteins and require the use of energy. The cell membrane also performs functions other than controlling the movement of materials into and out of the cell, and the membranes of some specialized cells have very complex functions. So we can see that the cell membrane is a very intricate and important component of the cell.