|
Created by eimearkelly3
about 11 years ago
|
|
Question | Answer |
A selectively permeable membrane | Allows some but not all substances to pass through |
A semi-permeable artificial membrane used in the lab | Visking tubing |
The use of energy to move molecules against a concentration gradient | Active transport |
Diffusion | The spreading out of molecules from a region of high concentration to a region of low concentration. This is due to the kinetic energy of molecules and is therefore passive (does not require external energy). Diffusion is said to take place across a concentration gradient. |
Adaptations of the alveoli to improve gas exchange | Large surface area (numerous alveoli) Thin walls Moist |
Solvent | A liquid that dissolves other substances e.g. water |
Solute | A substance that is dissolved e.g. salt or sugar dissolved in water |
Solution | Mixture of solvent and solute e.g. salty water |
Osmosis | The diffusion of water molecules across a semi-permeable membrane from a region of high water concentration to a region of low water concentration. (Also passive) |
Hypertonic solution | Lower concentration of water than the other solution |
Hypotonic solution | Higher concentration of water than the other solution |
Isotonic solution | Equal concentration of water to the other solution |
Animal cells in an isotonic solution | Remain the same, water moves in and out at the same rate. |
Animal cells in a hypotonic solution | Gain water due to osmosis (Amoeba have contractile vacuoles to prevent bursting) |
Animal cells in a hypertonic solution | Lose water due to osmosis, cells shrivels and dies (crenation) |
Examples of osmosis | Absorption of water by the plant roots Re-absorption of water by the proximal and distal convoluted tubules of the kidneys The turgor of plant cells gives support to non-woody cells Opening and closing of stomata Absorption of water by the stomach, small intestine, and colon. Flow of water in the amoeba |
Plant cells in an isotonic solution | Remain the same |
Plant cells in a hypotonic solution | Gain water due to osmosis, becomes turgid |
Turgor / turgor pressure | The pressure of the cytoplasm and the vacuole against the cell wall of a plant. |
Plant cells in a hypertonic solution | Lose water due to osmosis, the vacuole shrivel and move away from the cell wall. Becomes flaccid (limp) and wilts. The cell is then said to be plasmolysed. |
The reversal of plasmolysis | Deplasmolysis --> put the cells in a hypotonic solution |
Cell wall of bacteria | Polysacccharides / protein |
Cell walls of fungi | Chitin |
Food preservation by osmosis | Salting bacon/fish or preserving fruit and jam by adding sugar (hypertonic solution --> cell loses water --> enzymes no longer work --> cell dies) |
Want to create your own Flashcards for free with GoConqr? Learn more.