Please enable JavaScript.
Coggle requires JavaScript to display documents.
Biology test - Coggle Diagram
Biology test
Osomosis
Definition Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high water potential) to a concentrated solution (low water potential).
-
-
-
-
A high water potential solution (hypertonic) has a higher water concentration and a lower ion concentration than cells.
A low water potential solution (hypotonic) has a lower water concentration and a higher ion concentration than cells.
-
-
-
Diffusion
Definition: Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration. It describes the movement of particles in fluids.
-
-
Multicelluar Organisms
Multicellular organisms (with more than one cell) cannot just rely on diffusion. Their cells are too far from the external environment, and so they need a transport system with specialised surfaces to exchange molecules.
Plant Osomosis
Plasmolysis
Flaccid
When water moves out of cells by osmosis, cell volume decreases, so the cell becomes flaccid (floppy)
When water moves into cells by osmosis, cell volume increases, and the cell is said to be turgid (swollen).
If a plant cell loses a large amount of its water by osmosis, the cell volume may decrease so much that the cell membrane is pulled away from the cell wall.
Active transport
Active transport allows sugar molecules, which are needed for cell respiration, to be absorbed into the blood from the gut and the kidney, even when the sugar concentration of the blood is higher.
When the substrate binds to the carrier protein, the protein uses energy (from respiration) to change shape.
-
-