Transport across membranes Flashcards
Diffusion
The net movement of particles from an area of high concentration to an area of low concentration
Partially Permeable
Only some molecules can diffuse through them, (cell membranes)
Does diffusion require energy
No, it is a passive process, it is random movement from the particles
3 Factors that effect rate of diffusion
- Concentration Gradient
- Temperature
- Surface Area
Diffusion: Concentration Gradient
Larger concentration gradient means higher rate of diffusion
Diffusion: Temperature
Higher temperature means higher rate of diffusion as the particles are given more energy and move around faster so diffusion is increased (until optimum temp)
Diffusion: Surface Area
The larger surface area the higher rate of distance
Osmosis
Net movement of water molecules across a partially permeable membrane from an area of high water concentration to an area of low water concentration (diffusion of water)
Concentration of water
Not the volume of water but the proportion of water molecules to solute
Plant vs Animal Osmosis
When water molecules transfer into the cell by osmosis, for a plant, the cell becomes turgid as the cell wall prevents it from bursting. With animal cells if there is too much water, the cell can burst.
Active Transport
The net movement of molecules against their concentration gradient (low to high) across a cell membrane that requires energy from cellular respiration
Active Transport Part 2
It requires energy from the cell (respiration) (an active process), always takes place across a membrane and requires special proteins to transfer it across
Where is the energy from glucose stored?
In ATP molecules, it takes energy to the parts of the cell that need it
Root Hair Cells
Absorb water and mineral ions
Adaptation of Root Hair cell
- Contain lots of mitochondria (energy is used for active transport)
- Large surface area (greater active transport gradient)
