B2 Cell transport Flashcards
What is diffusion?
Net movement of particles from an area of high concentration to low concentration
Passive process (doesn’t require energy)
3 Factors that affect diffusion
Concentration gradient
Temperature
Membrane surface area
How are villi adapted for exchanging substances?
Long and thin (high surface area)
One-cell-thick membrane so there is a shorter area for diffusion
Good blood supply (maintains a steep concentration gradient)
How are alveoli adapted for efficient gas exchange?
Large surface area
Moist membranes
One-cell-thick membranes
Good blood supply
What is osmosis?
Diffusion of water from a concentrated solution to a dilute solution through a partially permeable membrane
An example of osmosis in plants
Water moves from the soil in to the root hair cell
What is active transport?
Movement of particles against a concentration gradient, using energy from respiration
Why is active transport needed in plant roots?
Concentration of mineral ions in the soil in lower than inside the root hair cells
What is the purpose of active transport in the small intestine?
Sugars can be absorbed when the concentration of sugar in the small intestine is lower than the concentration of sugar in the blood
Where is short distance required for diffusion? (3)
capillaries
membranes of cells
flattened shape of structures such as leaves
How is effective exchange maintained in alveoli?
Moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained.
This increases effective exchange.
What is the diameter of one alveoli?
300 μm
What does active transport require?
Energy
Osmosis RPA
What’s the independent variable?
sugar solution concentration
Osmosis RPA
What is the control variable?
surface area and volume of potato sample
time potato is in solution
