1.3 Transport In Cells Flashcards
diffusion
The net movement of particles or molecules from an area of high concentration to an area of low concentration
Particles
Units of matter
Concentration
A measure of how much solute, for example, is in a given volume of solvent
Solute
A substance that dissolves in a solvent
Solvent
Something that a solvent can be dissolved in
Temperature
How hot/cold something is
Osmosis
Movement of water particles from high concentration to a low concentration
Through a partially permeable membrane
Membrane
Organelle that controls what enters and exits a cell
Active transport
Movement of particles from low to high concentration, requiring energy
What three things affect the rate of diffusion?
- temperature
- difference in concentration
- surface area to volume ratio
Concept of concentration gradient
Particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced
‘[from p. 8] The bigger the difference in concentration (i.e the steeper the concentration gradient) the quicker diffusion will occur.’
The bigger the DIFFERENCE IN CONCENTRATION (i.e. the steeper the concentration gradient)…
The quicker diffusion will occur
Explain why a bacterium can rely on diffusion for gas exchange but animals need a transport system
- bacterium is smaller
- has larger SA:V ratio
- therefore diffusion can occur quickly enough
How does temperature affect rate of diffusion
As temperature increases particles gain more kinetic energy causing the particles to move more quickly, therefore diffusion happens more quickly.
Diffusion adaptations in LUNGS IN MAMMALS
Good blood supply - concentration grad
Millions of alveoli in each lung - sa:v
Alveolus wall only one cell thick - diff pathway
Ventilation of the lungs - concentration grad
Diffusion adaptations in SMALL INTESTINE IN HUMANS
Surface is folded to form villi and microvilli - sa:v ratio
Villi walls are one cell thick - diff pathway
Good blood supply - concentration grad
Diffusion adaptations in GILLS IN FISHHHHHh
Many gill filaments - sa:v
Filaments very thin - diff pathway
Good blood supply - concentration grad
Water pumped over gills - concentration grad
Diffusion adaptations in ROOTS AND LEAVES IN PLANTS
Many roots - sa:v
Root har cells are long - sa:v (because they’re long and thin)
Root hair cells are thin - short diff pathway
Leaves are flat and thin - diff pathway
OSMOSISSISISISISISISISSISISISIISSSS
Is the movement of water molecules across a partially permeable membrane from a high water potential to a low water potential
OSMOSIS MODLE ANSWER
Water will move VIA OSMOSIS from the __1__and into the __2__. This because the water potential of the solution of the __1__ is HIGHER (n.b. Remember to use comparative wording) than in the __2__.
OSMOSIS model answer for no movement
No net movement of water particles as the water potential inside the _______ and the ______ is the same.
Hypotonic solution
Solution outside has higher water potential
E.g. red blood cels will swell and burst :o
Plant cells like hypertonic solutions because the cell wall can withstand the pressure and it keeps the leaves stretched out flat and the stems upright
Isotonic solution
Both sides have same water potential
E.g. red blood cells are normal :)
Plant cells not great but bearable
Hypertonic solution
Solution inside has higher water potential than outside
E.g red blood cells shrivel and it affects o2 transport :(
Plant cells shrivel and WILTTTTT
Active transport
A method by which particles can cross membrane against a concentration gradient, but this process requires energy
