Topic 2 - Transport Across Membranes Flashcards
What is diffusion?
The movement of particles from an area of higher concentration to an area of lower concentration across a concentration gradient
Describe an experiment to show diffusion
Put visking tubing filled with starch and glucose into a beaker of iodine solution
After some time, the solution outside tests positive for glucose
but negative for starch, because, the glucose is small enough to
diffuse out of the tube into the solution from higher to lower
concentration but the starch is too big to fit out of the tube
What are the factors affecting the rate of diffusion?
Concentration Gradient
SA:Vol ratio
Distance
Temperature
How does Concentration Gradient affect the rate of diffusion?
The steeper the concentration gradient the faster the rate of diffusion
How does SA:Vol ratio affect the rate of diffusion?
The larger the SA:Vol ratio the faster the rate of diffusion
How does distance affect the rate of diffusion?
The smaller the distance the faster the diffusion rate
How does temperature affect the rate of diffusion?
The higher the temperature the faster the diffusion rate
What is osmosis?
The movement of water from an area of high water potential (concentration) to an area of low water potential (concentration) across a selectively permeable membrane
What does turgid mean in plant cells?
When there is a high water potential outside the cell causing water to move into the cell through osmosis. Making the cell turgid or filled with water.
What does flaccid mean in plant cells?
When there is an equal concentration of water outside and inside the cell
What does plasmolyzed mean in plant cells?
When there is a high water potential inside the cell causing water to move outside the cell through osmosis. Making the cell plasmolyzed or unfilled with water.
What is active transport?
The movement of molecules from lower to higher concentration using a specific carrier protein and energy. This is against a concentration gradient.
What do cells that carry out a lot of active transport have lots of and why?
Mitochondria to release the extra energy needed for the uptake.
