Diffusion, Osmosis and Active transport Flashcards
Diffusion
Is a movement of particles from an area of high concentration to an area of lower concentration. It happens in both solutions and gases.
Diffusion rate
- The bigger the concentration gradient, the faster the diffusion rate
- Higher temperature also give a faster diffusion rate, since particles have more kinetic energy, so move faster
- A surface area of the membrane
What can diffuse trough cell membrane?
Only very small molecules like oxygen, glucose, amino acids and water.
Big molecules such as starch and protein cannot fit trough.
The larger the surface area of the membrane, faster the diffusion rate is.
Osmosis
Is a movement of water molecules across a partially permeable membrane from an area of higher concentration of water to an area of lower concentration of water. It is a type of diffusion.
Partially permeable membrane
Membrane with very small holes in it. Only small molecules can pass trough e.g. water
Active transport
Some substances need to be absorbed against the concentration gradient. It requires energy from respiration to make it work.
Root hair-active transport
The concentration of minerals is usually higher in the root hair than in the soil. Therefore, root hair cannot use diffusion to take up minerals.
Active transport in human body
Is used in the gut where there is a low concentration of nutrients but high concentration of nutrients in blood. E.g glucose
Dilute solution
Have a high concentration of water.
Concentrated solution
Have a low concentration of water.
The cell wall prevents…
a plant cell from bursting and the cell becomes turgid.
Turgid
When a cell becomes swollen. In hypotonic solution. It is normal for plant cell but it will burst an animal cell.
Flaccid
In isotonic solution. It is normal for the animal cell but not for the plant cell. It causes the vacuole to shrink and the plant will no longer be firm and rigid.
Urea
Is a waste product, produced inside the cells. It diffuses out of the cells into a blood plasma and excreted by the kidneys.
Cytoplasm is made up of…
chemicals dissolved in the water. It is a concentrated solution of salts and sugars.
Hypotonic
If the concentration of solutes in the solution outside the cell is lower than the concentration inside the cell. The solution is hypotonic to the cell.
Isotonic
The concentration of solutes in the solution in and outside the cell is the same. The solution is isotonic to the cell.
Hypertonic
The concentration of solutes in the solution outside the cell is higher than the concentration inside the cell. The solution is hypertonic to the cell.
Plasmolysed
When the cell shrinks. In hypertonic solution. The cells die quickly unless the osmotic balance is restored.
Turgor
The pressure caused by vacuole, which swells and presses the cytoplasm against the cell wall. The pressure builds up until no more water can enter.
Turgor makes the cells…
hard and rigid, which keeps the leaves and stems of the plant rigid and firm.
Glucose is actively absorbed out of…
gut and kidney tubules into the blood.
The single-celled organism has…
a large surface area to volume ratio. All the necessary exchanges occur across its surface area.
Multicellular organisms have…
many organ systems, specialised for exchanging materials.
The effectiveness of an exchange surface is increased by:
- a large surface area that is thin(provide a short diffusion path)
- having an efficient blood supply
- being ventilated(for gaseous exchange), to maintain a steep gradient
