3A- Osmosis, Diffusion, Active Transport and Transpiration Flashcards
Define osmosis.
The movement of water molecules across a semi-permeable membrane from a region of high to low concentration.
How does water move in and out cells?
Through osmosis. Tissue fluid surrounds the body, with oxygen and glucose dissolved in it. It’s squeezed out of the blood capillaries.
How does a cell having lacking or excess water inside it change the solution inside it?
If it’s short of water, the solution inside becomes concentrated. If it has lots of water the solution inside it becomes more dilute.
What 4 factors make exchange surfaces for diffusion, osmosis and active transport more effective?
Thickness of the membrane
Large surface area
High blood supply
Ventilated (in animals)
What diffuses into and out of the leaf?
CO2 diffuses in and oxygen and water vapour diffuse out.
The size of the stomata is controlled by
Guard cells
Where does diffusion take place in the body?
Gas exchange in the lungs
Absorption in the intestine
How are alveoli adapted to maximise diffusion?
Large surface area
Thin
Good blood supply
Moist lining
When substances are absorbed against the concentration gradient it is called
Active transport
How are roots adapted for active transport?
Hairs which give them a large surface area so they can absorb the maximum amount of water and mineral ions
Where is active transport relevant in humans?
In the gut, moving a high concentration of nutrients from the gut to the blood
Define Transpiration Stream
Movement of water from the roots through the xylem and out of the leaves
Which tube transports water and which tube transports food?
Xylem and Phloem
Which factors affect transpiration?
Humidity
Wind
Temperature
Light
Increasing temperature on a plant does what to transpiration?
Increases rate of transpiration because the water evaporates faster from the leaves while it is hotter
