KA1.2 Cell Transport Flashcards
Define Diffusion
The movement of molecules down a concentration gradient from a high concentration to a lower concentration.
Define Osmosis
The movement of water from a region of high water concentration to a region of low water concentration through a selectively permeable membrane.
What is Active Transport ?
The movement of molecules and ions against a concentration gradient, from a region of low concentration to a region of high concentration. IT REQUIRES ENERGY.
What is passive Transport?
Passive transport is the movement of molecules down a concentration gradient from a high concentration to a lower concentration, and does not require energy for it to take place.
What is an isotonic solution?
solution containing equal water concentrations
What is a hypertonic solution?
solution containing a higher water concentration
What is a hypotonic solution?
lower water concentration
What is the cell membrane?
The cell membrane
- controls the movement of molecules into and out of the cell
- described as selectively permeable.
- is made up of two types of molecule: proteins and phospholipid.
Why is diffusion important?
Diffusion is important to cells because it allows them to gain the useful substances they require to obtain energy and grow, and lets them get rid of waste products.
What would happen to an ANIMAL cell if it was placed in a ISOTONIC solution
An animal cell would remain unchanged if it was placed in a solution containing equal water concentrations (isotonic).
What would happen to an ANIMAL cell if it was placed in a HYPOTONIC solution
A cell would increase in mass if it was placed in a solution containing a higher water concentration (hypotonic), as water molecules would enter the cell.
An animal cell would BURST.
What would happen to an ANIMAL cell if it was placed in a HYPERTONIC solution
A cell would decrease in mass if it was placed in a solution containing a lower water concentration (hypertonic), as water molecules would leave the cell.
An animal cell would SHRINK in this case.
What would happen to a PLANT cell if it was placed in a ISOTONIC solution
A plant cell would remain unchanged if it was placed in a solution containing equal water concentrations (isotonic).
What would happen to a PLANT cell if it was placed in a HYPOTONIC solution
A cell would increase in mass if it was placed in a solution containing a higher water concentration (hypotonic), as water molecules would enter the cell.
A plant cell would swell, become TURGID.
What would happen to a PLANT cell if it was placed in a HYPERTONIC solution
A cell would decrease in mass if it was placed in a solution containing a lower water concentration (hypertonic), as water molecules would leave the cell.
A plant cell would become PLASMOLYSED.
What is the concentration gradient?
The difference in the concentration of a substance between two areas is called the concentration gradient.
what does selectively permeable mean?
It is described as selectively permeable. This means that only some molecules can move across the membrane.
What increases the rate of diffusion?
The bigger the difference in the concentration gradient , the steeper the concentration gradient and the faster the molecules of a substance will diffuse.
When will diffusion stop?
Diffusion stops when the concentration of the substance is equal in both areas. This does not mean that the molecules of substance are not moving any more, just that there is no overall movement in one direction. Molecules of substance are moving equally in both directions.
What type of molecules move by diffusion?
Molecules which move by diffusion have to be small and soluble, for example glucose, oxygen, carbon dioxide and amino acids. Large, insoluble molecules such as starch are unable to move by
diffusion.
