biology chapter 3 Flashcards
what is diffusion
the net movement of particles from a region of higher concentration to a region of a lower concentration down a concentration gradient, as a result of a random movement
what is a concentration gradient
the difference in concentration between two regions
why is diffusion called the passive transport
It does not need any energy
When does diffusion occur?
When there is concentration gradient
(one side has to be high and the other side have it be low)
What direction do particles move
high to low
Why is diffusion important in oxygen movement
To ensure that oxygen is always supplied throughout the body
what are the factors affecting the rate of diffusion
temperature and diffusion distance
how does temperature affect the rate of diffusion
increasing the temperature increases the kinetic energy of particles. The particles will collide or bounce onto one another at a faster rate. This will increase their rate of diffusion
how does the diffusion distance affect the rate of diffusion
how fast a substance travels depend on the distance it has to pass through. The distance through which a substance diffuses is called the diffusion distance. The shorter the diffusion distance, the faster the rate of diffusion
what is osmosis
osmosis is the diffusion of the water molecules across a partially permeable membrane, from a region of high water potential to a region of a low water potential
what is a partially permeable membrane
A partially permeable membrane is a membrane which enables some substances to cross, but prevents others from doing so.
Water molecules are able to cross membranes as they are very small. The larger molecules in the cytosol are too large to get through the cell membrane
what is a solute
a substance that is being dissolved
what is a solvent
the liquid that dissolves the solute
what is a solution
a mixture that forms after a solute and a solvent has been mixed together
what is a water potential
water potential is the tendency for water to leave a solution
HOW DOES WATER ENTER AND EXIT CELLS?
Water diffuses across the partially permeable membrane through channels in the membrane called aquaporins.
what are the importances of osmosis in plants
- It enables cells to maintain their water content despite evaporation.
- It provides turgidity to softer tissues, enabling support.
- It enables the absorption of water by root cells.
- It enables the movement of water through the plant through the xylem tissue.
- Root tips remain turgid which helps them penetrate soil.
The opening and closing of stomata is determined by whether the guard cells are turgid or flaccid
what happens to a cell in a solution with a higher concentration of water
when a cell is placed into a solution with a higher concentration of water ( the diluted solution) , the water molecules will move from a region of high water potential to a region of a low water potential across a partially permeable membrane. The cell will swell or eexpand in size.
what happens to a cell in a solution of the same water potential
the cells immersed into a solution with the same water potential as their cytoplasm will not change their size or shape
what happens to a cell in a solution with a lower concentration of water
when a cell is placed into a solution with a lower concentration of water, the water molecules will move from a region of a higher concentration, into a region of a lower concentration. The plant cell will decrease in size and become limp.
why is turgor important in plants
turgor plays an important role in maintaining the shape of the soft tissues in plants. urgor is what makes living plant tissue rigid. Loss of turgor, resulting from the loss of water from plant cells
what are the differences in diffusion and osmosis
diffusion
- net movement of a substance, gaseous or solute
- movement of particles down a concentration gradient
- partially permeable membrane is not required
osmosis
- net movement of water molecules
- movement of water molecules from a diluted solution to a more concentrated solution
- partially permeable membrane is required
what is an active transport
the movement of particles through a cell membrane, from a region of a low concentration to a region of their higher concentration. Active transport occurs against the concentration gradient of a particle, requiring energy from respiration.
where does active transport occur
it only occurs in living cells because living cells respire. It is during respiration that energy is released, and part of this energy is used in active transport
