diffusion, facilitated diffusion, and osmosis Flashcards
(22 cards)
What is diffusion?
Movement of particles from a high concentration to a low concentration without energy input.
When does diffusion stop?
When equilibrium is reached – particles are evenly spread out.
Is energy required for diffusion?
No, it’s a passive process.
Give an everyday example of diffusion.
Spraying perfume – the scent spreads from high concentration (spray) to low concentration (room).
What is facilitated diffusion?
Passive movement of large or charged particles across a membrane using proteins.
What types of proteins are used in facilitated diffusion?
Channel proteins and carrier proteins.
What is the role of a channel protein?
Acts as a tunnel allowing specific substances to pass freely.
What is the role of a carrier protein?
Binds to a molecule, changes shape, and carries it across the membrane.
Is facilitated diffusion passive or active?
Passive – it does not require energy.
Define osmosis.
The diffusion of water from high water concentration (low solute) to low water concentration (high solute) through a semi-permeable membrane.
What is a solute?
A substance that is dissolved in a solvent.
What is a solvent?
The substance that dissolves the solute (usually water).
What is a solution?
A mixture of solute and solvent.
What does ‘isotonic’ mean?
Solute concentration inside and outside the cell is equal – no net movement of water.
What does ‘hypotonic’ mean?
The outside fluid has less solute (more water) – water enters the cell; cell may swell or burst.
What does ‘hypertonic’ mean?
The outside fluid has more solute (less water) – water leaves the cell; cell may shrink.
What is osmotic pressure?
The pressure created by water moving across a membrane due to osmosis.
What is a systematic error?
A consistent error that affects the accuracy of results (e.g. faulty equipment).
What is a random error?
An unpredictable error that affects the precision of results.
What is reliability in experiments?
The consistency of results when an experiment is repeated.
What is validity in experiments?
Whether the experiment measures what it’s supposed to.
What is the difference between channel and carrier proteins?
Channel proteins form a tunnel across the entire cell membrane, allowing molecules and ions to pass through freely. Carrier proteins bind to one particular molecule or ion, flip, and then let go of said molecule or ion into the cell, successfully transporting it across the membrane.
