1.3 Transport in cells Flashcards
Diffusion
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient. It is a passive process which means that no energy is needed. It occurs until an equilibrium is reached. There will be a faster rate of diffusion when…
A greater difference in concentration
A higher temperature as the particles will have more kinetic energy and move faster
A larger surface area of membrane for particle to diffuse across
A shorter diffusion distance
Osmosis
Osmosis is the net movement of water molecules from a dilute region to a concentrated region, down a concentration gradient across a partially permeable membrane. It is a passive movement
Hypotonic solution
The outside of the cell is more dilute than the inside of the cell (more water outside)
In animal cells, too much water may enter, and the cell will swell until it bursts (lysis)
In plant cells, when too much water enters, it fills the vacuole, and this pushes it against the cell wall making it turgid. They will not burst as the have a rigid cell wall
Hypertonic solution
The outside of the cell is more concentrate than the inside of the cell (less water outside)
In animal cells, too much water may leave, and the cell will shrink and shrivel (crenation)
In plant cells, when to much water leaves, the vacuole shrinks, and the cell becomes flaccid. they will not shrivel up because they have a rigid cell wall.
Plasmolysis is shrinking of the cytoplasm away from the cell wall of a living cell due to water loss by osmosis
Practical 3 (osmosis)
IV - concentration of solution
DV - percentage change in mass
CV - temperature, volume of solution, size of potatoes
Procedure - Prepare samples of potatoes and place in different concentrations of sugar or sodium chloride solution.
Make measurements of mass and length of your samples before and after soaking them in solutions.
Calculate the percentage change in mass of plant tissue.
Plot, draw and interpret appropriate graphs.
Active transport
The movement of particles from an area of low concentration to an area of high concentration through a partially permeable membrane against a concentration gradient and it requires energy.
