Biology- Diffusion, Osmosis and Active Transport Flashcards
Osmosis is….
the movement of water from an area of high water concentration to
an area of low water concentration through a partially permeable membrane.
Hypotonic=
low concentration- not many ions
Hypertonic=
high water concentration
A bigger number of moles means…..
a stronger solution
Isotonic is ……
when the water concentration both sides
of the partially permeable
membrane is the same. Therefore there is no net movement of water.
Diffusion-
The movement of a substance from an area
of high concentration to an area of low concentration.
Molecules have ‘moving’ energy. This is called kinetic energy and this is what drives the diffusion. This is a passive process ie no external source of energy is required.
Active transport is…..
the movement of molecules from a region of lower
concentration to a region of higher concentration using energy from respiration.
Is a cell membrane permeable, impermeable or partially permeable?
Partially permeable
Is a cell wall permeable, impermeable or partially permeable?
Permeable
Explain why red blood cells burst if they are put into water.
There is a very low water concentration inside the red blood cell so water molecules from outside
the cell diffuse very quickly, so much so that the
cell bursts.
Exchange surfaces are specialised in many organisms:
They have a high surface area to volume ratio
They are thin so they have a short distance for diffusion
In animals, the surface area has an efficient blood supply
In land animals, there is ventilation for gas exchange