B1 Diffusion (page 17) Flashcards
What is Diffusion?
Its the gradual movement of particles from places where there are lots of them to places where there are fewer of them - it’s just the natural tendency for stuff to spread out
DIFFUSION is the SPREADING OUT of particles from an area of HIGHER CONCENTRATION to an area of LOWER CONCENTRATION.
Does Diffusion happen in solutions, gas, or both? and why?
Diffusion happens in both solutions and gasses - that’s because the particles in these substances are free to move about randomly.
(Please see the diagram on page 17 of what is happening when the smell of purfume diffuses through the air in a room)
What is the simplest type of diffusion?
the simplest type is when different gasses diffuse through each other. This is what’s happening when the smell of perfume diffuses through the air in a room
(see diagram on page 17)
The bigger the concentration gradient, (the difference in concentration), is the diffusion rate faster or slower?
faster
The higher a temperature is, will also give a slower or faster diffusion rate, and why?
it will give a faster infustion rate because the particles have more energy so move around faster.
What do a Cell Membrane do?
they’re clever because they hold the cell together BUT they let stuff in and out as well.
How can dissolved substances move in and out of cell? and why?
by diffusion. Only very small molecules can diffuse through cell membraines though things like oxygen (needed for respiration - (see pg 55)), also glucose, amiono acids and water.
Can Big molecules like starch and proteins fit through the membraine of a cell?
No - they are too big.
(loook at diagram on pg 17 of protein, starch, amino acid and glucose)
How do particles flow through the cell membrane, like diffusion in air?
they flow through the cell membrane from where there’s a higher concentration (a lot of them), to where there’s a lower concentration (not such a lot of them).
They’re only moving about randomly of course, so they go both ways - but if there are a lot more particles on one side of the membrane, there’s a net (overall) movement from that side.
The larger the surface area of the membrane, what is the faster or slower the diffusion rate, and why?
the faster the diffusion rate - because more particles can pass through it at once (see page 20).
A student adds a drop of ink to a glass of cold water;
a) What will the student observe to happen to the drop of ink. Explain your answer (2 marks)
b) How might the obervation differ if the ink was added to a glass of warm water? (1 mark)
a) The ink will diffuse/spread out through the water (1 mark). This is because the ink particles will move from where is a higher concentration of them (the drop of ink) to where there is a lower concentration of them (the surrounding water) - (1 mark).
b) The ink particles will diffuse/spread out faster (1 mark).
