Transport Across Membranes Flashcards
What is the cell membrane made out of?
Phospholids
Protiens
Some molecules can form__________________
Channels or “pores”. Some describe the membrane to be porous
The cell membrane is selectively permiable. What does this mean?
it controls what substances enter and leaves the cell
What is Passive Transport?
When a substance moves down a concentration gradient. (from high to low concentration)
How much energy is required for passive transport
0
What are (2) examples of passive transport?
Diffusion and osmosis
What is Diffusion
The movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
What is Osmosis
The movement of water from an area of high water concentration to an area of low water concentration across a selectively permiable membrane
What will happen in an animal cell if it is placed in distilled water
It will gain water and swell. It may even burst
What will happen in an animal cell if it is placed in a strong salt solution
The cell will lose water and shrink
What does Turgid Mean
The term used to describe a plant cell which has swollen due to the entry of water by osmosis
What does plasmolysed mean
The term used to describe a plant cell whose contents have shrunk due to loss of water by osmosis
What will happen to a plant cell in distilled water
Will gain water and swell < turgid
What will happen to a plant cell in a strong salt solution
will lose water and shrink (plasmolysed)
Examples of Substances that move INTO a cell by diffusion
Glucose
Oxygen
Carbon Dioxide
Exampled of Substances that move OUT OF a cell by diffusion
Carbon dioxide
Oxygen
What prevents a plant cell from exploding
Cell wall
Does active transport require energy
Y
Describe (using water concentrations) why a plant cell loses weight in a strong solution
Water moves from a high concentration (inside the cell) to a low concentration area (outside the cell)
Active transport is the movement of…
molecules from a low concentration to a high concentration AGAINST a concentration gradient through a selectively permiable membrane
What sugar moves into a cell by diffuion
glucose
What part of the cell membrane allows it to be fluid?
phospholipid
What substance has molecules too large to pass through a cell membrane
Starch
What allows molecules to cross the cell membrane
the pores in protiens
