1.2 Membrane transport Flashcards
roughly how thick is cell membrane
7mn
what is the cell membranes made for
phospholipid bilayer and membrane protein
why do we have a control experiment
to compare the results of an experiment where no treatment is applied
Convert 5 mm to µm.
5000 µm
What does a selectively permeable membrane mean?
Membrane that only allows some types of substances to pass through
Define passive transport
Down the concentration gradient and does not require energy.
Name two types of passive transport in cells
Diffusion and osmosis
Define diffusion
The movement of molecules down a concentration gradient from a higher to a lower concentration
Define osmosis
The movement of water molecules from a high water concentration to a low water concentration through a selectively permeable membrane
Name a substance that diffuses into our cells for use.
Oxygen, glucose
Name a substance that diffuses out of our cells to be removed.
Carbon dioxide, urea
What does ‘net movement’ mean?
Overall movement: the direction that most of the particles are moving in
State three factors that affect the rate of diffusion.
Concentration gradient, temperature, surface area
How does concentration difference affect the rate of diffusion?
Higher concentration difference/Steeper concentration gradient –> faster diffusion
If a cell is in a solution of a lower water concentration, water will ___ (enter/leave) the cell.
Leave
If a cell is in a solution of a higher water concentration, water will ___ (enter/leave) the cell.
Enter
What will happen to an animal cell in a lower water concentration?
Water leaves cell –> shrinks
What will happen to an animal cell in a higher water concentration?
Water enters cell –> burst
Why do animal cells burst in lower water concentration solutions?
No cell wall
What will happen to a plant cell in a lower water concentration?
Water leaves cell –> plasmolysed
What will happen to a plant cell in a higher water concentration?
Water enters cell –> turgid
What does ‘plasmolysed’ mean?
The cell membrane pulls away from cell wall
How do we calculate % change in mass?
(final mass - initial mass)/initial mass x 100
Define active transport
The movement of molecules and ions against the concentration gradient using energy and membrane proteins
Explain the importance of active transport in plants.
Root hair cells carry out active transport to absorb mineral ions effectively in dilute soil
State one adaptation cells may have if they need to carry out active transport.
Lots of mitochondria to release energy via aerobic respiration
How does active transport differ from diffusion and osmosis?
Active transport uses energy, diffusion and osmosis do not
State two differences between diffusion and osmosis.
D: Any particles, does not need a membrane; O: Water specific, needs partially permeable membrane
