B3 Movement into and out of cells Flashcards
What is diffusion?
Net movement of particles from high to low concentration.
What causes diffusion to happen?
Random movement of particles.
Is energy needed for diffusion?
No, diffusion is passive.
What direction is diffusion?
Down a concentration gradient (high to low).
Why is diffusion important for cells?
It helps substances like oxygen and glucose enter the cell.
What substances move by diffusion?
Gases (O2, CO2), solutes (like glucose).
What part of the cell controls diffusion?
The cell membrane.
What factors affect diffusion?
Concentration gradient, temperature, surface area, distance.
What is osmosis?
Net movement of water from high to low water potential.
What type of membrane is used in osmosis?
Partially permeable membrane.
What is water potential?
How “free” water molecules are; high in dilute, low in concentrated solutions.
What happens if a plant cell is in dilute solution?
It becomes turgid (swollen).
What happens if a plant cell is in concentrated solution?
It becomes flaccid or plasmolysed.
What does turgid mean?
Full of water and firm.
What is turgor pressure?
Pressure inside a plant cell pushing on the cell wall.
What does flaccid mean?
Water lost; cell soft.
What is plasmolysis?
Cell membrane pulls away from cell wall due to too little water.
Why is osmosis important?
Helps cells take in or lose water, keeps them firm or balanced.
What happens to an animal cell in a dilute solution?
It swells and may burst (lysis).
What happens to an animal cell in a concentrated solution?
It shrinks (crenates).
What is active transport?
Movement of particles from low to high concentration using energy.
What energy is needed for active transport?
ATP from respiration.
Where does active transport happen in the body?
In root hair cells (minerals), small intestine (glucose).
How are root hair cells adapted for active transport?
They have many mitochondria for energy and a large surface area.
