Movement into and out of cells Flashcards
Define diffusion
the net movement
of particles from a region of their higher
concentration to a region of their lower
concentration (i.e. down a concentration
gradient), as a result of their random movement
Where does energy from diffusion come from?
kinetic energy of random movement of
molecules and ions
State that some substances move into and out of
cells by diffusion through…
cell membranes
Describe the importance of diffusion of gases and
solutes in living organisms
Diffusion is important to cells because it allows them to gain the useful substances they require to obtain energy and grow, and lets them get rid of waste products.
state the factors that influence diffusion
surface area, temperature,
concentration gradient and distance
Describe the role of water
solvent in organisms with reference to digestion, excretion
and transport
Describe osmosis
net movement of
water molecules from a region of higher water
potential (dilute solution) to a region of lower
water potential (concentrated solution), through
a partially permeable membrane
describe the effects on red blood cells of immersing them in solutions of different concentrations
Red blood cells placed in a solution with a higher water concentration compared to their contents (eg pure water) will gain water by osmosis, swell up and burst.
Water will diffuse from a higher water concentration outside the cell to a lower water concentration inside the cell.
Red blood cells placed in a solution with a lower water concentration compared to their contents (eg 1.7 per cent salt solution) will lose water by osmosis and shrink.
Water will diffuse from a higher water concentration inside the cell to a lower water concentration outside the cell.
water diffuses through…
partially
permeable membranes by osmosis
State that water moves into and out of cells by …
osmosis through the cell membrane
what are plants are supported by?
pressure of water inside the cells pressing outwards on the
cell wall
Describe active transport
movement of particles through a cell membrane from a region
of lower concentration to a region of higher
concentration (i.e. against a concentration
gradient), using energy from respiration
Explain the importance of active transport
process for movement of molecules or ions
across membranes, including ion uptake by root
hairs
State that protein carriers move molecules or
ions across a membrane during…
active transport
What does a turgid cell refer to?
refers to cells or tissues that are swollen from water uptake
What does flaccid cell refer to?
floppy or loose, and cells have drawn in and pulled away from the cell wall.
What does a cell that is plasmolyzed really mean mean?
This is when the cytoplasm shrinks due to the loss of water but the cell wall fails to shrink due to its tough structure. The cytoplasm eventually tears away from the cell wall.
What is turgor pressure?
pressure from fluid within the cell pushing against the cell wall
Investigate and describe the effects on plant
tissues of immersing them in solutions of
different concentrations
Plant cells placed in a solution with an equal water concentration to the contents of their cytoplasm and vacuole (dilute sugar solution) will not experience an overall change in volume. No osmosis occurs.
Plant cells placed in a solution with a low water concentration compared to their contents (concentrated sugar solution) will lose water by osmosis. Their cell membranes will peel away from their cell walls and they are said to be plasmolysed.
Water will diffuse from a higher water concentration inside the cell to a lower water concentration outside the cell.
Plant cells placed in a solution with a high water concentration compared to their contents (eg pure water) will gain water by osmosis and swell up until their cytoplasm and cell membrane are pushing against their cell wall. They are said to be turgid.
Water will diffuse from a higher water concentration outside the cell to a lower water concentration inside the cell. The presence of the plant cell wall prevents plant cells from bursting.
concentration gradient define it
The difference in concentration between two solutions, between different cells or between cells and a surrounding solution
why is diffusion of gases important?
because it allows for gas exchange in organisms to provide useful gases for processes like respiration and for the removal of waste materials
Why is diffusion of solutes important?
useful for uptake of solutes from soil by plants
How does the concentration gradient affect rate of diffusion?
greater the concentration gradient, the faster the diffusion
How does the surface area of the membrane affect rate of diffusion?
as surface area increases, so does the rate of diffusion as there is more space for particles to move throgh
