Study "osmosis", a flashcard deck on FORKSAI.
Define diffusion and provide an example of this process in biological systems.
Diffusion is the movement of molecules from areas of high concentration to areas of lower concentration. An example is the diffusion of oxygen into cells and carbon dioxide out of cells.
How are cell membranes selectively permeable, and what role do proteins play in this characteristic?
Cell membranes are selectively permeable because they allow some, but not all, materials to pass through. Proteins embedded in the membrane facilitate the passage of certain chemicals, either by diffusion or active transport, while acting as barriers to others.
Define osmosis and provide an example of where it occurs.
Osmosis is the movement of water from an area of high concentration to an area of lower concentration across a semi-permeable membrane. An example is water moving into an animal cell when it is immersed in pure water.
Explain what is meant by the term 'turgid' in the context of plant cells.
A plant cell is said to be turgid when it has absorbed water, causing the cytoplasm to push against the cell wall. The cell wall prevents the cell from bursting, leading to an increase in internal pressure.
Describe how turgidity is used in plants for support.
Turgor pressure, the force of the cell contents against the cell wall, is crucial for plant structure. When plant cells are turgid, they become firm, providing rigidity and support to the plant, which helps it stand upright.
Explain how a high salt or sugar concentration can be used to preserve food.
High concentrations of salt or sugar preserve food by creating an environment where microorganisms lose water through osmosis. This osmotic dehydration causes the microbial cells to shrivel and die, preventing food spoilage.
Describe a simple experiment to demonstrate osmosis.
An experiment to demonstrate osmosis could involve placing a plant cell (like a potato slice) into solutions of varying salt concentrations. By observing changes in the potato's mass or firmness, one can infer the movement of water due to osmosis.
Distinguish between a solute, a solvent, and a solution.
A solute is a substance that is dissolved, such as salt. A solvent is the liquid that dissolves other substances, with water being the most common. A solution is the mixture formed when a solute dissolves in a solvent, like saltwater.
Why is osmosis considered a special form of diffusion?
Osmosis is considered a special form of diffusion because it involves the movement of molecules (specifically water) from a region of higher concentration to a region of lower concentration. The key distinction is that osmosis occurs across a selectively permeable membrane.
What is osmoregulation, and why is it important for organisms like Amoeba?
Osmoregulation is the control of water and salt levels within a cell or organism. For organisms like Amoeba, which live in freshwater, osmoregulation is vital to prevent excessive water intake by osmosis, often managed by structures like contractile vacuoles.