Summary
Movement into and out of cells involves processes like diffusion, osmosis, and active transport. These processes help in the movement of substances across cell membranes.
- Diffusion — passive movement of molecules from high to low concentration. Example: Oxygen moving from alveoli to blood.
- Osmosis — movement of water through a partially permeable membrane from a region of high water potential to low water potential. Example: Water moving into plant roots from the soil.
- Active Transport — movement of particles from low to high concentration using energy from respiration. Example: Ion uptake by root hairs.
Exam Tips
Key Definitions to Remember
- Diffusion: Passive movement of molecules from high to low concentration.
- Osmosis: Movement of water through a partially permeable membrane from high to low water potential.
- Active Transport: Movement of molecules from low to high concentration using energy.
Common Confusions
- Diffusion vs. Osmosis: Diffusion applies to all molecules, osmosis is specific to water.
- Active Transport vs. Diffusion: Active transport requires energy, diffusion does not.
Typical Exam Questions
- What is osmosis? Movement of water through a partially permeable membrane from high to low water potential.
- How does diffusion occur in the alveoli? Oxygen moves from high concentration in the alveoli to low concentration in the blood.
- What is the role of active transport in root hairs? It moves ions from the soil into the root hairs against the concentration gradient using energy.
What Examiners Usually Test
- Understanding of the differences between diffusion, osmosis, and active transport.
- Ability to explain the direction of movement in osmosis and diffusion.
- Knowledge of examples where each process occurs in biological systems.