Biology Part A 1 Flashcards
A solution of pure water is separated from a concentrated sugar solution by a partially permeable membrane in what direction do the molecules flow and why?
The water will flow into the concentrated sugar solution. Through osmosis because the sugar molecules are to big to go the other way.
Define osmosis
Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration
Define diffusion
Diffusion is where particles move from an area of high concentration to an area of low concentration
How have exchange surfaces adapted to maximise effectiveness (three points)
They are thin so there is only a short distance to diffuse
They have a large surface area so more can diffuse at once
In animals exchange surfaces have lots of blood vessels to get stuff in and out of the blood quickly
How is a leaf adapted to increase diffusion? (At least three points)
Flattened shape increases surface area
Interior cell walls from another exchange surface
Air spaces inside the leaf increase surface area
Guard cells regulate diffusion to be efficient
Lots of individual stomata
What is the function of the lungs?
To transfer oxygen to the blood and remove waste carbon dioxide from it
How are the alveoli specialised to maximise diffusion
An enormous surface area
A moist lining for dissolving gases
Very thin walls
A good blood supply
Define active transport
Active transport is the movement of a substance from an area of low concentration to an area of high concentration or “against the gradient”
Where does active transport occur?
In root hair cells and in the gut
