C1L7: Diffusion Flashcards
Define diffusion
Net movement of particles in a solution or a gas from an area of high concentration to an area of lower concentration
What are 3 factors which affect diffusion?
- temperature
- concentration
- SA:V ratio
How does temperature affect diffusion?
particles gain energy & move faster to area with less particles
How does concentration gradient affect diffusion?
if there is a large concentration gradient, particles from concentrated area will move faster to area with less particles
How does SA:V ratio affect diffusion?
larger SA:V ratio speeds up rate of diffusion
How are the lungs adapted for efficient exchange? (5 reasons)
- large SA = spherical alveoli
- thin walls = 1 cell thick creates shorter diffusion pathway
- permeable walls = allows gas through easier
- capillaries = rich blood supply
- steep conc. grad. = increases rate of diffusion
What gases are exchanged in the lungs?
- CO2 exhaled
- Oxygen inhaled
How does CO2 enter a plant?
via stomata
How does CO2 diffuse into plants?
- CO2 enters stomata
- CO2 fills air spaces
- diffuses down conc grad to palisade cells
By which process does water enter a plant?
osmosis
How does water diffuse into plants?
- water enters root hair cell via osmosis
- water moves through other root cells until it reaches xylem
- xylem moves water from roots to leaves
- water diffuses into leaves
Explain the steep conc. grad. in plants
constant use of CO2 & water for photosynthesis requires more needed
Explain the short diffusion distance in plants
leaves are thin which shortens the diffusion distance
Explain the large SA in plants
- large cell membrane in root hair cells hair-like projection
- lots of cell membrane in contact with air spaces
Explain the steep conc. grad. in the digestive system
continuous blood flow creates a steep conc. grad.
