Movement Of Molecules Flashcards
Definition of diffusion
The random movement of molecules from a high concentration to a low concentration
Diffusion happens through the walls of alveoli in lungs where CO2 pass from the blood to the alveolus and O2 passes from the alveolus to the blood. Why?
High concentration of CO2 to low concentration from blood to alveolus.
High concentration O2 to low concentration from alveolus to blood
Rate of movement of molecules in and out of cells is increased by …. (4 things)
Higher temp
Higher concentration gradient
Large surface area to volume ratio. (Large area, small volume)
Small distance
Cells which rely on diffusion maximise their surface area and minimise their volume. Explain why a red blood cell is a biconcave disc shape?
Largest surface area and smallest volume
Definition of osmosis?
Osmosis is the movement of free water particles from an area of high concentration to area of low concentration over a semi permeable membrane.
What are free water molecules?
Water molecules not attached to any other molecule
What is a semi permeable membrane?
Only allows certain particles through (e.g. Might let smaller particles through)
Describe water potential
Water potential measures free water molecules in a solution.
In osmosis, water moves from area of high water potential to ….
Low water potential.
Describe what happens to a cell when placed in an isotonic solution
Same water potential inside and outside the cell so no net movement
Describe what happens when a cell is placed in a hypotonic solution
Hypotonic Solution … has a higher water potential outside cell than inside cell.
Net movement of free water particles into cell
Describe the net movement of free water molecules when a cell is placed in a hypertonic solution
Solution outside cell has lower water potential than inside the cell
Net movement of free water particles out of the cell
What causes a turgid cell?
The water in Turgid cells supports plants. If plant loses a lot of water it will wilt.
Definition of active transport
Active transport is the movement of molecules from an area of low concentration to area of high concentration using energy
Active transport uses a special protein called …
A carrier molecule or protein
