B1 & B2 Cell Structure and Transport Flashcards
What is Diffusion ?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient.
What is water potential ?
Water potential is the ability of water to move freely .
What is osmosis ?
It is the diffusion of water from a more dilute solution to a more concentrated solution , across a semi permeable membrane.
What is dilute concentration ?
Higher water potential , higher water concentration and lower solute concentration.
What is a concentration ?
Lower water potential , lower water concentration and a higher solute concentration
What are the factors that effect diffusion ?
Temperature and concentration gradient .
How does temperature affect diffusion?
an increase in temperature means the particles in a gas or a solution move around more quickly. When this happens , diffusion takes place more rapidly as the random movement of the particles speed up.
How does concentration gradient affect diffusion?
diffusion is fastest when the gradient is steepest ( ie the difference in concentration greatest )
- This is because there are no more particles
What is active transport?
A method of transporting molecules or ions across a membrane against a concentration gradient, moving molecules or ions from a region of low concentration to one high concentration.
Give one examples of active transport?
The sodium-potassium pump in nervous impulses. Here sodium ions are pumped out of the cell and potassium ions are pumped into the cell.
What does the active transport process require ?
Energy in from of the ATP(adenosine triphosphate) it is needed for the active transport system to carry a molecule across the membrane and then return to its original position. This energy is produced during respiration.
What is isotonic ?
If a concentration of solutes in the solution outside the cell is the same as the internal concentration , the solution is isotonic to the cell.
What is hypertonic ?
If a concentration of solutes in the solution outside the cell is higher than the internal concentration, the solution is hypertonic to the cell.
What is hypotonic?
If a concentration of solutes in the solution outside the cell is lower than the internal concentration, the solution is hypotonic to the cell
Why is osmosis in animal cells important ?
It is important to animal cells because if a cell uses up water in a chemical reaction, the cell needs osmosis to remove some of the water to balance the cell. It also works the opposite way.
