transport Flashcards
diffusion, SA:V ratio, osmosis, osmosis required practical
define diffusion
the net movement of particles in a liquid or gas from an area of high concentration to an area of a low concentration
–> down the concentration slide
why does diffusion happen
this is due to the random movement of particles and no energy is needed other than kinetic energy –> which the particles already have
a process where no energy is needed other than the energy that you already have is called a PASSIVE process
what does no net movement mean
no net movement is when the concentration is the same in both areas so no particles have to move from one area to the other
explain fully the concentration gradient
the greater the difference in concentration between two areas the faster the rate of diffusion.
The difference between the two areas of concentration is called the concentration gradient.
–> diffusion occurs down a concentration
the steeper the concentration gradient the faster the diffusion
explain the effect of temperature
When the temperature is increased the particles will move and collide around more which increases the rate of diffusion
a higher temperature means faster diffusion
explain the 3 organs involved in diffusion
1. what substances diffuse
2. what are the adaptations
LUNGS
1. oxygen diffuses from the lungs into the blood
carbon dioxide diffuses out the blood into the lungs
2. the ALVEOLI are moist air sacs equipped with thin walls so it’s easier for gases like oxygen and carbon dioxide to dissolve easily and get through.
they also have a big surface area and good blood supply.
SMALL INTESTINE
1. glucose, amino acids, and fatty acid diffuse from the intestine into the blood
2. VILLI have a massive surface area and they have a single layer of surface cells and a very good blood supply
LEAF
1. oxygen and water vapor diffuse out of the leaf
carbon dioxide diffuses in
2. LEAVES have a big surface area with little holes (stomata) which the CO2 diffuses into.
the veins let the leaf stay open and the leaves are thin
explain the function of SA:V ratio
large organisms need transport systems to survive.
very small organisms don’t need transport systems and they can get all the materials in diffusion alone.
this is because they have a large surface area to volume ratio.
SA:V ratio formula and conclusion
surface area is the number of faces x the area of one face.
volume is length x width x height
as the independent variable (length of the side of cube) gets bigger the dependent variable (SA:V) ratio decreases
define osmosis
this is the net movement of water MOLECULES from a DILUTE solution to a CONCENTRATED solution across the PARTIALLY PERMEABLE MEMBRANE
similarities between diffusion and osmosis
diffusion and osmosis are similar as they are
- both passive processes
- the water moves down or concentration gradient –> just like particles move down a concentration slide/gradient
describe the 3 solutions of osmosis and how the water moves
ISOTONIC
when the concentration of a solution surrounding a cell is THE SAME as the concentration of the solution inside the cell
HYPOTONIC
when the solution surrounding a cell is MORE DILUTE than the solution inside the cell
HYPERTONIC
when the solution surrounding the cell is LESS DILUTE (MORE CONCENTRATED) than solution inside the cell
how the movement of water affects plant and animal cells
NO NET MOVEMENT
no effect on animal and plant cells
FROM OUTSIDE TO INSIDE CELL (HYPOTONIC)
animal cell bursts (cytolysis)
plant cells will become very hard (turgid)
FROM INSIDE TO OUTSIDE CELL (HYPERTONIC)
animal cells will shrivel up (creation)
plant cells become flaccid and plasmolysed
osmosis required practical
METHOD:
1. take the same size samples of potato from the same potato
2. cut off the skin off the samples so water is allowed in (skin doesn’t let water in)
3. measure the samples in mm and then weigh them in grams –> do that to two decimal places and record both results for all for three samples
4. put each sample into different test tubes
- add 100ml of distilled water into one
- 100ml of slightly sugary water (0.25m sucrose) into the other
- 100 ml of sugary water (0.5m sucrose) into the last one
5. take the sample out of each one after letting them sit and roll each one on a tissue paper to get rid of excess liquid (could alter results)
6. measure, using the same equipment, the mass and the length again for all three samples –> record these results as well
7. calculate the difference in mass and length for each one (your most recent result - your first one)
CONVERT INTO PERCENTAGE CHANGE –>
change in mass/initial mass x 100
- draw a graph with change in mass on the y-axis and concentration of sugar on the
x-axis
CONCLUSION
as the concentration of sugar increases the gain of mass decreases and the loss of mass increases
