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Bella Nat 5
U1 KA 2 Transport across membranes
| Question | Answer |
|---|---|
| What is Diffusion | The movement of molecules of a substance FROM their area of HIGHER concentration TO their area of LOWER concentration until they are evenly spread. |
| What happens to the rate of diffusion when there is a steeper concentration gradient | It is faster |
| Name 2 substances that diffuse INTO cells in the tissues | Oxygen, Glucose, Amino Acids, Water |
| Name 2 substances that can diffuse out of cells in the tissues | Carbon dioxide, Urea Water |
| What do you call the holes found in cell membranes | Pores (or channels) |
| What size must molecules be to be able to diffuse into and out of cells | Small |
| What is the name we give to a membrane that chooses what can pass through it? | Selectively permeable |
| What are the names of the 2 different types of molecule which make up the cell membrane | Phospho-lipid molecules, Protein molecules |
| Is diffusion Active or Passive | Passive |
| What does Passive mean | Does not require Energy |
| What is Osmosis | The name for the diffusion of water |
| Define Osmosis | Osmosis is the movement of WATER molecules from their area of higher water concentration to their area of lower water concentration THROUGH A SELECTIVELY PERMEABLE MEMBRANE. |
| Is Osmosis Active or Passive | Passive |
| Define Active transport | The movement of molecules AGAINST their concentration gradient from an area of LOWER concentration to an area of HIGHER concentration. |
| Does Active Transport require energy? | Yes |
| What happens to ALL cells when placed in 100% water? | They GAIN mass by osmosis. |
| What happens to ALL cells when placed in a solutions of a lower water concentration? | They LOSE mass by osmosis. |
| What happens to ALL cells when placed in a solution with the same water concentration as their cytoplasm? | Nothing |
| What eventually happens to animal cells in solutions with a water concentration GREATER than the cell cytoplasm? | BURST |
| What eventually happens to animal cells placed in a solution with a water concentration LESS than the cell cytoplasm? | SHRIVEL |
| What eventually happens to PLANT cells in solutions with a water concentration GREATER than the cell cytoplasm? | They swell up and become TURGID |
| What eventually happens to PLANT cells in a solution with a water concentration LESS than the cell cytoplasm? | They shrivel and become PLASMOLYSED |
| What direction do molecules or ions move during active transport? | Against the concentration gradient. |
| What molecule must be present in the cell membrane for active transport? | Protein |
| Does active transport need energy? | Yes |
| Name a molecule or ion that can be moved into or out of a cell by active transport. | Sodium or Potassium or Iodine |