3. Movement in and out of cells
3.1 Diffusion
Describe diffusion as the net movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement
State that the energy for diffusion comes from the kinetic energy of random movement of molecules and ions
State that some substances move into and out of cells by diffusion through the cell membrane
Describe the importance of diffusion of gases and solutes in living organisms 5 Investigate the factors that influence diffusion, limited to: surface area, temperature, concentration gradient and distance
Diffusion
Investigating how surface area effects diffusion
Investigating the effect of temperature on diffusion
3.2 Osmosis
Describe the role of water as a solvent in organisms with reference to digestion, excretion and transport
State that water diffuses through partially permeable membranes by osmosis
State that water moves into and out of cells by osmosis through the cell membrane
Investigate osmosis using materials such as dialysis tubing
Investigate and describe the effects on plant tissues of immersing them in solutions of different concentrations
State that plants are supported by the pressure of water inside the cells pressing outwards on the cell wall.
Supplement
Describe osmosis as the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane
Explain the effects on plant cells of immersing them in solutions of different concentrations by using the terms: turgid, turgor pressure, plasmolysis, flaccid 9 Explain the importance of water potential and osmosis in the uptake and loss of water by organisms.
Osmosis
Osmosis investigation
Types of solution
3.3 Active transport
Describe active transport as the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration Supplement
Explain the importance of active transport as a process for movement of molecules or ions across membranes, including ion uptake by root hairs
State that protein carriers move molecules or ions across a membrane during active transport.
Active transport 1
Active transport 2
Transport in cells - Overview