Diffusion, Osmosis And Active Transport Flashcards
What is diffusion?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration - down the concentration gradient
This is a passive process
How can the rate of diffusion be affected?
Concentration, the greater the difference in concentration between two areas the faster diffusion occurs
Temperature as the temperature increases, the molecules have more kinetic energy increasing the rate
Pressure if there is high pressure, the molecules will quickly move from the area of high pressure to low pressure
What is osmosis?
Osmosis is the net movement of water molecules from an area of high concentration to an area of low concentration across a selectively permeable membrane
Describe the semi permeable membrane
The semipermeable membrane has tiny pores which are small enough to allow smaller molecules like water to pass through but doesn’t allow larger molecules such as sugar to pass through. When the membrane is boiled it becomes denatured. This causes the post to become larger and both water and solute are able to pass through both ways.
Explain what happens to animal cells through osmosis
red blood cells in a weak, hypotonic, salt, solution ( high water con) burst, because they have no cell wall
red blood cells in an isotonic solution, (equal water con) cause water concentration to be equal both inside, and outside the cell resulting in known movement in either direction, the cell stays the same
Red blood cells in a strong hypertonic salt solution (low water con) have a higher con inside compared to outside the cell they shrink through osmosis
Describe what happens to plant cells through osmosis
Plant cells in a hypotonic solution will swell up till they become turgid. They will not burst because they have a strong cellulose cell wall.
Isotonic solution means there will be no net movement of water in either direction, and the cells will remain the same size
Hypertonic solution causes cell content shrink away from cell wall as osmosis occurs, leading the plant to wilt the cell is plasmolysed
What does visking tubing represent?
The semi-permeable membrane
Explain the visking, tubing experiment
The visking tubing is a selectively permeable membrane water moves by Iosis from high water concentration in the beaker into a low water concentration in the visking tubing across the membrane, increasing the volume of liquid in the rising tubing, which forces liquid up the capillary tube
What is active transport?
Active transport is the movement of molecules against the concentration gradient, (up the gradient) using ATP energy realised during respiration
Explain carrier proteins
Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient
What 2 substances are needed for active transport?
ATP and Oxygen
Advantages of diffusion
It moves down a concentration gradient. No energy is needed. Therefore it is passive it moves, dissolved, solutes and gases and dissolved. Gases also diffuse
Advantages of osmosis
Osmosis moves down a concentration gradient. It is a passive process. It moves water and a partially permeable membrane is needed.
Advantages of active transport
It moves up the concentration gradient energy is needed in the form of ATP. It moves dissolved, solute, and a carrier protein is needed.
