What is the difference between diffusion and osmosis? What makes a membrane semipermeable?
What characteristics of a molecule affect whether it can pass through the plasma membrane of a cell?
In the simulation, when protein molecules were evenly distributed on both sides of the membrane, was the solution isotonic, hypertonic, or hypotonic?
Which direction was water flowing?
In the simulation, when protein molecules were more highly concentrated on the inside of the cell than outside of the cell, was the solution isotonic, hypertonic, or hypotonic?
Which direction was water flowing?
Why is it important that the plasma membrane surrounding cells is semipermeable?
What would happen if it were not semipermeable?
1) Diffusion : Is the movement of molecules / ions from a region of higher to lower concentration. It may or may not occur across a semi permeable membrane.

In diffusion there is no challenge involved as it is along the concentration gradient, but in active transport movement of molecules occur against concentration gradient ie; from lower to higher concentration.

2) For active transport, energy is vital for movement, in this case protein molecules function as molecular pumps to enable the cell accumulate glucose/ions, against concentration gradient. Here metabolic energy ATP is required.

3)Facilitated diffusion is a type of passive transport in which ions/molecules cross the semi permeable membrane because permeases present in the membrane facilitate the transport.
Like simple diffusion facilitated diffusion doesn't require metabolic energy and simply occurs across the concentration gradient.

4) Osmosis : is movement of water from hypotonic solution (lower concentration) to hypertonic solution (higher concentration) through a semi permeable membrane.
The cell membrane being permeable to water allows to and from movement of water molecules along the concentration gradient.
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Diffusion is the process of a substance moving from an area of high concentration to an area of lower concentration. Osmosis is a type of diffusion where water moves across a semipermeable membrane still from an area of high concentration of water to an area of lower concentration of water. This corresponds to water moving from an area with a low concentration of solute to an area with a higher concentration of solute.
A semipermeable membrane allows some substances to pass through it.
The plasma membrane of a cell allows small uncharged molecules to pass through it, but not large molecules and not charged ions.
The protein molecules were evenly distributed on both sides of the membrane, so this solution was isotonic.
In an isotonic solution, water moves both in and out of the cell, which was observed in the simulation.
The protein molecules were more highly concentrated on the inside of the cell, so this solution was hypotonic.
In hypotonic solutions, water moves into the cell to help dissolve the higher amount of solute inside the cell, which was observed in the simulation.
A semipermeable cell membrane is important to allow some molecules, like proteins, to be more highly concentrated inside the cell than outside the cell. If the cell membrane were permeable, the molecules on the inside of the cell would exit the cell and be evenly distributed in the cell and in its environment.
If the cell membrane were not permeable at all, the cell would not be able to receive nutrients from its environment.