B2 - Diffusion & Active Transport Flashcards
Give 2 things that need to be true if diffusion is going to happen
When there are higher concentrations of molecules in certain areas than others
When the molecules are free the move around
What is diffusion?
The spreading out of particles from an area of high concentration to an area of low concentration
What is a passive process?
A process that requires no energy and happens naturally
Why does diffusion happen?
The particles collide and bounce off to less populated areas
Why is diffusion needed in plants?
So that the carbon dioxide diffuses into the stomata
In cells, in what way does diffusion occur?
Substances diffuse in and out of the cell membrane
What occurs when diffusion can’t deliver all the substances required?
Active transport
What is active transport?
Transport of molecules forcefully meaning energy from respiration is used for this to happen
What does the phrase “going against the concentration gradient” mean?
When molecules travel from less dense areas to more dense areas
What do cell membranes do?
They hold the cell together
They are partially permeable membranes meaning that smaller molecules can diffuse through but larger molecules can’t
