Biology Flashcards
Diffusion
The movement of particles from an area of high concentration to an area of low concentration
Why do molecules in liquid tend to spread out
Molecules in liquids and gases constantly moving and bumping into each other
Net movement
Movement of particles from an area of high concentration to an area of low concentration
Why is there net movement
Due to random movement of particles
Diffusion and osmosis is passive process
Passive process -
Process where no energy is needed
Concentration gradient
A difference in concentration between 2 areas
Why is diffusion important
So particles can spread out from one side of a room to another
Factors affecting diffusion
Concentration gradient
Temperature
Large surface area
What factors make diffusion faster
Large concentration gradient
Higher temperature
Large surface area
What happens when surface area to volume ratio falls
a cell will either divide or die
Why is it important for multicellular organisms to have exchange surfaces and transport systems
So substances can pass in and out of the cells
How are exchange surfaces adapted for sufficent molecules to be transported in and out of cells
Large surface area
Provides more space for diffusion of gases
What happens when there is a small difference in concentration between 2 areas
The net movement by diffusion will be slow
How to work out net movement
Particles moving in - particles moving out
What happens the bigger difference in concentration
Steeper concentration gradient
Faster rate of diffusion
What does large surface area compared to volume of cell do
Allows transport of molecules in and out of the cell to meet needs of an organism
Why is surface area to volume ratio important in biology
Makes a big difference to the way animals exchange substances with the environment
Osmosis
Movement of water from a dilute solution to a more concentrated solution
Where does water move in osmosis
Water always moves to areas of lower water concentration
What does the cell wall do while Osmosis is taking place
Stops the cell from bursting
Turgid cell
Cells in a dilute solution
Flaccid cell
Cells in concentrated solutions
What happens to cells in the same solution
Stay the same
Plasmolysed cell
A cell when cytoplasm is pulled away from the cell wall
Which cell has the membrane and which cell has the cell wall
Plant cell - cell wall
Animal call - membrane
Lysis
When water moves into an animal cell the cell membrane stretches and the cell gets bigger
What happens when animal cells are put in concentrated solutions
They lose water by osmosis until they become shrunken
Where does Osmosis travel
Through a partially permeable membrane
Isotonic solution
Any external solution with the same solute concentration and water concentration compared to body fluids
