Part 2 - Transport Across Cell Membranes Flashcards
What happens in animal cell osmosis when the concentration is high/low?
In higher concentraion, the cell will burst because they have no cell wall
Higher water concentration outside cell, water moves down concetraion gradient into cell
In lower water concentration cell will shrink
Higher concentration inside cell, water moves down concentration gradient out of cell
What happens in plant cell osmosis when the concentration is high/low?
In a higher concentration cell is described turgid
Higher concentration outside cell, water moves into cell
In low water concentration, cells are described as plasmolysed
Higher water concentration inside cell then moves out
Diffusion
An example of passive transport
The movement of molecules from a higher concentration to a lower concentraion through a selectively permeable membrane until concentrations are equal.
Substances enter the cell by diffusion along a concentration gradient
What is a concentration gradient
The difference in concentration that exists between two regions resulting in diffusion
Explain how substanes enter and exit the cell by diffusion
Harmful substances build up inside the cell, leave the cell by diffusion from a higher concentration inside the cell to a lower concentration outside the cell
Why is diffusion important to cells
It allows cells to gain the raw materials for respiration
It allows cells to remove harmful waste products
What are solutions usually made up by?
A solution is often made by dissolving a substance in water e.g a 5% glucose (/water/salt/sugar) solution will contain:
5% glucose (/water/salt/sugar) and 95% water
What has the highest concentration?
Pure water
The cells will always gain water and mass
Water always moves from higher to lower concentration
More dilute solutions have a …. ?
Higher concentration of water
More concentrated solutions have a …?
Lower water concentration
Explain the effects osmosis has on plant cells with a 0.85% salt solution inside it (when immersed in pure water? Immersed in 0.85% salt solution? Immersed in concentrated salt solution?)
When immersed in pure water, water moves inside vacuole and swells up (TURGID)
When immersed in 0.85% salt solution there is no change because the water concentrations are equal
When immersed in concentrated salt solution, the water moves out and the cell shrivels up (PLASMOLYSED)
Explain the effects osmosis has on red blood cells with a 0.85% salt solution inside it (when immersed in pure water? When immersed in a 0.85% salt solution? Immersed in 1.7% salt solution?
When immersed in pure water the water moves inside the cell, swells up and bursts (lysis)
When immersed in 0.85% salt solution there is no change because water concentrations are equal
When immersed in 1.7% salt solution, water moves out and the cell shrivels up
What is active transport?
The movement of molecules/ions from a lower concentration to a higher concentration against a concentration gradient and requires energy for membrane proteins to move molecules and ions against the concentration gradient.
What are the factors that affect the rate of active transport?
Oxygen concentration because its needed for respiration
Glucose concentration because it is a respiratory substrate
Temperature because enzymes are involved
What are the 4 variables in experiments?
Independent variable- the one YOU are going to change
Dependent variable- what happens “the results”
Controlled variable- the ones that must be kept the same for a valid experiment
Control- set up to sure that any change in results is due to the variable that is altered
