Transport in Cells Flashcards
what is diffusion?
The random movement of particles from an area of high concentration to an area of low concentration (down a concentration gradient) until there is no net movement and equilibrium is reached.
what state can diffusion occur in?
- solid
- gas
what is a concentration gradient?
difference in concentration
the bigger the concentration gradient…
the faster the rate of diffusion
why does temperature affect diffusion?
- higher temp
- particles carry more energy and move around faster
- faster rate of diffusion
how does surface area affect diffusion?
- larger surface area of membrane
- more contact
- more particles can pass through
- faster rate of diffusion
how does diffusion distance affect diffusion?
- shorter diffusion distance
- particles can go through more quickly
- faster rate of diffusion
list 4 factors which affect diffusion
- concentration gradient
- temp
- surface area
- diffusion distance
small organisms have a higher SA:V ratio than larger organisms
- diffusion can happen through a large area of small organism
- makes diffusion useful for transporting molecules
large multicellular organisms have a small SA:V ratio
- need transport system with specialised surface to exchange molecules
- cells are too far from the environment
-
how are alveoli adapted to transfer gases in the lungs?
large surface area
if an animal has a large SA:V ratio…
it can lose heat quickly
what type of molecules can diffuse through a cell membrane?
- small molecules e.g oxygen, glucose, amino acids and water
- big molecules can’t fit through membrane e.g proteins and starch
what does concentration mean?
mass of a solute per unit volume
does diffusion require energy?
- no
- particles still move randomly
- but concentration of different areas stay the same
explain why we dissolve cocoa powder into warm milk instead of cold
- higher temp provides particles more energy
- diffusion will be quicker
what is osmosis?
the movement of water particles from a region of high water concentration to a region of low water concentration across a partially permeable membrane