B1 Active Transport Flashcards
What is diffusion?
Diffusion is the net movement of gas or liquid particles from an area of high concentration to an area of low concentration
What factors would speed up diffusion?
An increase in temperature, A large difference in the concentration gradient, Short diffusion distance, States of matter
What is active transport?
Active transport is the process used by cells to move minerals across all membranes in the plant roots. This goes against the concentration gradient, as minerals travel from an area of low comcentration (the roots of the soil) to an area of high concentration (the plant cells)
What is Osmosis?
Osmosis is a special type of diffusion, where plants gain water and sustenance from roots. It is the passage of water through a non permeable membrane which results in a difference in concentration gradient, such as through the cell membrane from an area of low concentration to an area of high concentration
What is a hypertonic concentration?
If the concentration of solutes in the solution outside the cell is lower than the internal concentration, the solution is hypertonic to the cell
When is a solution isotonic to the cell?
If the concentration of solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell.
What is a hypotonic solution?
If the concentration of solutes in the solution outside the cell is higher than the internal concentration the solution is hypotonic to the cell
Hypotonic, hypertonic and isotonic solution concentrations occur in what cells?
Animal cells
When a plant cell’s vacuole and cytoplasm is swelled with water and it becomes rigid and tough, what does it become?
Turgid
Although, if the solution surrounding the plant cells is hypertonic, (more concentrated than), then water will leave the cell by Osmosis. A lack of water causes the cells to shrivel up and become soft as there is no pressure on the cell wall. The plant will then wilt.
This is known as a Flaccid plant cell
A plant cell can become plasmolysed…
If too much water is taken out of the vacuole by osmosis causing the cytoplasm to detach from the cell wall and collapse
Osmosis required practical
Instructions:
1. Cut out 3 potato samples each the same diameter using an apple corer
2. Cut off the potato skin at both sides of the sample; this is solid and will not allow water through
3. Measure each sample and record it, also weigh the mass on the weighing scale
4. Write out the measurements on a results table
5. Put one of the samples into a tube filled with 10ml of water
6. Next, place the second sample into a tube with 0.25 moles of Sucrose
7. Place the last sample into a tube filled with 0.5 moles of sucrose
8. Leave the samples to rest for an extended period
9. Remove them from the tubes and place them onto sieves
10. Rub them onto a dry towel, then weigh and measure them
11. There should be a difference in their weights and measurements, with a pattern of the higher sugar concentration resulting in a lower mass and weight. Put this data into a graph to show your results.
