Biology- Diffusion And Osmosis Flashcards
Can diffusion take place in solids?
No, diffusion only takes place in liquids and gases as particles move about during diffusion
Why does diffusion happen more quickly in a gas compared to a liquid ?
Because the particles in a gas are widely spaced and move more quickly (than particles in a liquid)
What is diffusion?
The movement of particles of a substance from one place to another.
Key point : they move from an area where there are lots of them (high concentration) to an area where there are fewer of them (low concentration)
True or false ?
In diffusion, gas particles move from an area of low concentration to an area of high concentration of particles
FALSE
The other way round diffusion goes from an area of high concentration to low concentration
Particles do still move about randomly but there will be a net (this means ‘overall’) direction of movement from high concentration to low concentration.
Look at figure 1 to consider the effect of concentration on the speed of diffusion.
Is diffusion faster or slower in the bottom picture?
Slower
How do gas particles move about?
They move about randomly
Gases in a room have particles that move about and bounce off one another, in this way gases can move across a room.
Give an every day example of diffusion?
If perfume is sprayed, the gaseous smell moves and spreads out by diffusion from a high concentration area (where it was first sprayed) to an area of low concentration (further away from where it was first sprayed).
Is diffusion a passive or active process?
Passive, it happens without energy inputs.
(An active process, not a passive process, is one that needs energy to occur).
Diffusion occurs in biological systems. Open up the info sheet in your biology text book.
Where does diffusion take place in a fish?
In the gill of a fish (on the side of a fish on its head). The gill filaments have thin surfaces that allow gas exchange to occur.
Diffusion occurs in biological systems. Open up the info sheet in your biology text book.
Respiration is a process in humans which starts in the lungs, name two gases that diffuse during respiration?
Oxygen
Carbon dioxide
Oxygen comes from the air breathed in. It diffuses (by moving across the thin lining of the aveoli) into the blood so it can be carried around the body
Cells in the body make carbon dioxide during respiration, this goes into the blood where it is carried to the lungs. Carbon dioxide diffuses from the blood across the lining of the alveoli into the lungs.
Diffusion occurs in biological systems. Open up the info sheet in your biology text book.
Where does diffusion take place in an earth worm?
Oxygen diffuses Through the thin skin into the blood vessels of an earthworm.
Carbon dioxide produced in the cells of the earthworm is transported in the blood and gets transferred by diffusion out of the body of the worm (diffusion across the thin skin of the earthworm )
How does oxygen get converted to carbon dioxide?
In cells by RESPIRATION
Diffusion occurs in biological systems. Open up the info sheet in your biology text book.
Where does diffusion take place in a plant?
Lots of examples….. (look at the diagram)
Carbon dioxide is released by respiration (oxygen is taken up for respiration to occur)
Carbon dioxide is taken up by the plants for photosynthesis (oxygen is released after photosynthesis)
Places, where this occurs -the leaf surfaces , note the large flat surfaces are good for gas exchange.
Pores (holes in the leaf ) are called stoma and diffusion can occur inside the stoma
What is osmosis?
It is movement of particles of a solvent (water for example) across a semi permeable membrane
From a less concentrated solution to a more concentration solution
(See Figure 2)
It’s the solvent that is moving (figure 2 water)
Not the solute, the larger molecule such as sugar
Is osmosis active or passive?
Passive, it does not need energy to occur.
Is osmosis a type of diffusion?
Yes it is a specific type of diffusion , look at the figure 2 model for osmosis
What is the main feature of a membrane across which osmosis can occur?
It is semi permeable. This means it lets the solvent pass through but not the larger (solute ) particles.
What happens to a cell if it is placed in pure water ?
Clue , it’s to do with osmosis
It will swell as water molecules pass across the cell membrane by osmosis?
This process dilutes the contents of the cell.
What is a feature of a cell membrane that enables osmosis to occur.
It is semi-permeable
Not everything can pass across it, but some things can, e.g. water
Can diffusion happen in liquids?
Yes think of some liquid ink dropped into liquid water.
Diffusion occurs , the high concentration of ink diffuses into the area of low concentration (clear water) so that the liquids become mixed.
Particles of a substance that are liquids or gases move about randomly bumping into one another (or the molecules in the surrounding medium) what is this motion called?
Brownian motion
What is a passive process?
One that does not need energy
What is the opposite of a passive process?
An active process
If a process is active, what does this mean?
It needs energy to occur.
Without energy it can’t happen
Is a cell wall a semi permeable membrane ?
No
A CELL MEMBRANE IS
but not a cell wall
