Wayne Rooney
2.2 Movement in and out Cells
1 Define diffusion
Diffusion is the net movement of molecules from a region of higher concentration to a region of lower concentration down a concentration gradient, as a result of their random movement
2 Describe the importance of diffusion of gases and solutes and of water as a solvent.
Gases
Necessary for gas exchange in all living organisms
Necessary for obtaining Carbon Dioxide and releasing oxygen during photosynthesis.
Solutes (liquids)
Dissolved salts dissolve through root hair cell.
Absorption of dissolved food material in many organisms, like amoeba, bacteria and fungi is carried out through diffusion.
Some digested food material is absorbed by diffusion
Water as a solvent
Plants cannot obtain minerals unless they are dissolved in water
Enzymes and hormones cannot be secreted unless they are dissolved in water
Excretory products cannot be excreted unless they are dissolved in water.
3 Define osmosis (Supp. only)
Osmosis the diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution), through a partially permeable membrane.
4 Describe the importance of osmosis in the uptake of water by plants, and its effects on plant and animal tissues. The importance of osmosis
Plants gain water through osmosis in their roots from the soil. Without a water potential gradient,water will be loss from the roots . Plant cells contain vacuoles, which, if not full with water, will cause the cell to become flaccid. If all the cells in a leaf become flaccid, the whole leaf will become flaccid, hence causing the plant to wilt. Plant cells therefore need water to remain turgid and keep firm.If an animal cell surrounded with a high water potential, osmosis will take place, and if the water is not expelled some way or another, the cell will burst. This is because an animal cell doesn’t have a cell wall to keep it strong. If an animal
1 Define diffusion
Diffusion is the net movement of molecules from a region of higher concentration to a region of lower concentration down a concentration gradient, as a result of their random movement
2 Describe the importance of diffusion of gases and solutes and of water as a solvent.
Gases
Necessary for gas exchange in all living organisms
Necessary for obtaining Carbon Dioxide and releasing oxygen during photosynthesis.
Solutes (liquids)
Dissolved salts dissolve through root hair cell.
Absorption of dissolved food material in many organisms, like amoeba, bacteria and fungi is carried out through diffusion.
Some digested food material is absorbed by diffusion
Water as a solvent
Plants cannot obtain minerals unless they are dissolved in water
Enzymes and hormones cannot be secreted unless they are dissolved in water
Excretory products cannot be excreted unless they are dissolved in water.
3 Define osmosis (Supp. only)
Osmosis the diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution), through a partially permeable membrane.
4 Describe the importance of osmosis in the uptake of water by plants, and its effects on plant and animal tissues. The importance of osmosis
Plants gain water through osmosis in their roots from the soil. Without a water potential gradient,water will be loss from the roots . Plant cells contain vacuoles, which, if not full with water, will cause the cell to become flaccid. If all the cells in a leaf become flaccid, the whole leaf will become flaccid, hence causing the plant to wilt. Plant cells therefore need water to remain turgid and keep firm.If an animal cell surrounded with a high water potential, osmosis will take place, and if the water is not expelled some way or another, the cell will burst. This is because an animal cell doesn’t have a cell wall to keep it strong. If an animal