Cell Transport Flashcards
What is diffusion?
The spreading out of particles from a high to a low concentration.
Does diffusion need energy?
No, it’s a passive process.
Which direction do particles move in diffusion?
From high to low concentration (down the concentration gradient).
Where does diffusion happen in humans?
- Oxygen into blood in alveoli
- Carbon dioxide out of blood in alveoli
- Nutrients into blood in small intestine
- Urea from cells into blood (to be removed)
Where does diffusion happen in plants?
CO₂ into leaves through stomata
O₂ out of leaves (from photosynthesis)
Where does diffusion happen in fish?
- Oxygen from water into gill filaments
- Carbon dioxide from blood out into water
Name three factors that affect the rate of diffusion?
- Concentration gradient
- temperature
- membrane surface area
What is osmosis?
The movement of water molecules from an area of high water concentration to an area of low water concentration
Is osmosis a passive process?
Yes, no energy is needed.
Where does osmosis happen in plants?
Water moves from soil into root hair cells.
What is active transport?
Movement of particles from a low to high concentration using energy.
Does active transport need energy?
Yes – it uses energy from respiration.
Where does active transport happen in plants?
Mineral ions move into root hair cells from the soil.
Where does active transport happen in humans?
Sugar is absorbed from the small intestine into the blood, even when the blood has a higher concentration.
What features help exchange surfaces?
Large surface area
Thin membrane (short diffusion path)
Good blood supply
Good ventilation (lungs)
How are fish gills adapted?
Lots of thin gill filaments
Big surface area
Good blood flow
Steep concentration gradient
How are root hair cells adapted?
Long projection for big surface area
Thin walls
Absorb water & minerals by osmosis & active transport
How are alveoli adapted?
Large surface area
Thin walls (1 cell thick)
Good blood supply
Short diffusion path
How are villi in the small intestine adapted?
Big surface area
Thin wall
Capillary network
Fast absorption of nutrients
What increases the rate of diffusion?
Bigger concentration difference
Higher temperature
Larger surface area
