Diffusion & Osmosis Flashcards
Definition of diffusion?
the movement of molecules from an area of high concentration to an area of low concentration
Difference between permeable and impermeable?
permeable: if the substance can pass through it
impermeable: cannot pass through it
What does selectively permeable mean?
allows some but not all molecules pass through
Does diffusion require energy? It is known as?
does not require energy, it is known as passive transport
Give 2 examples of diffusion.
in the lungs, O2 diffuses into the blood through the alveoli
food coloring in water
What 4 factors affect the rate at which diffusion takes place?
temperature
distance
particle size
concentration
Discuss temperature in affecting the rate at which diffusion takes place?
diffusion happens at a faster rate at higher temperatures, particles have more energy
Discuss distance in affecting the rate at which diffusion takes place?
the shorter the distance, the faster the rate of diffusion
Discuss particle size in affecting the rate at which diffusion takes place?
the smaller the particle size, the faster the rate of diffusion
Discuss concentration in affecting the rate at which diffusion takes place?
diffusion will take place at a faster rate when there is a greater concentration difference between solutions
Osmosis definition?
is the movement of water molecules across a selectively permeable membrane from a region of high concentration to a region of low water concentration
Does osmosis require energy? It is X?
does not require energy, it is passive
Osmosis is a special type of diffusion, why?
requires a membrane (must be across a selectively permeable membrane)
water only that moves (involves the movement of water molecules)
Low water concentration = ?
High water concentration = ?
high solute
low solute
What is a solvent? Eg?
a liquid that dissolves other substances, eg: water
What is a solute? Eg?
a substance that has been dissolved , eg: salt/sugar
What is a solution? Eg?
the mixture of solvent and solute, eg: water and sugar
A solution of equal concentration is called?
isotonic
What does isotonic mean?
a solution of equal concentration
If an animal cell in a solution that is the same concentration as it’s cytoplasm, water will?
move in and out through its cell membrane at the same rate
A less concentrated solution (low solute) is called?
hypotonic
What does hypotonic mean?
a less concentrated solution
If an animal cell is in a solution that is less concentrated than the cell, the water will? What happens to the cell?
move into the cell as a result of osmosis
the cell will enlarge and may burst and swell
Eg of animal cells in less concentrated solution?
fresh water is less concentrated than the cell contents of amoeba
A more concentrated solution (high solute) is called?
hypertonic
What does hypertonic mean?
a more concentrated solution
Animals cells is in a solution that is more concentrated than the cell, water will? What happens the cell?
move out of the cell as a result of osmosis
the cell will shrivel
Plant cell walls are: selectively/semi permeable, permeable or fully permeable?
fully permeable
Plant cell walls let what through?
water, gases, many solutes (sugar, salt)
Cell wall gives a certain amount of X to a plant cell?
strength
Turgor, or turgor pressure means?
the outward pressure of the cell contents (cytoplasm and vacuole) pushing against the cell wall
How can plasmolysed cells be restored to normal by doing what? Give eg.
placing them in a less concentrated solution
eg: water
(Plant cells in more concentrated solution), the more concentrated solution does what? What happens the cell?
the more concentrated solution fills the space between the cell membrane and the cell wall
the cell loses turgor pressure
Regarding osmosis and food preservation, osmosis is sometimes used for?
to kill microorganisms and stop them decaying food
Bacteria and fungi are similar to plants as?
they also have a cell wall, their cells have a high water content
Give examples of food preservation techniques based on osmosis.
- foods like fish can be soaked in a high concentration salt solution, any microorganisms in or on the fish will lose water and die as a result of osmosis.
- fruits can be preserved in the form of jams and marmalades by using a high sugar concentration, this dehydrates (plasmolyse the cell) microorganisms and prevents them from growing
Osmoregulation meaning?
the maintenance of water and salt balance in an organism
