Movement Of Molecules Flashcards
Give a definition for diffusion
Movement of molecules from an area of high concentration to an area of lower concentration.
What is osmosis?
Osmosis is the movement of water molecules from a region of high concentration to a region of low concentration across a partially permeable membrane
What is meant by the term concentration gradient?
Change in concentration of a substance from one area to another
Molecules will move from high to low concentration
What is a turgid cell?
Water enters by osmosis, vacuole swells and pushes against cell wall
What is a flaccid cell?
Water lost from cell, vacuole shrinks, cell loses shape
How does active transport work in a cell?
The absorption of a substance by a cell against its concentration gradient, using energy specific molecules
Give some examples of situations when a substance cannot be moved into a cell by osmosis or diffusion, and how active transport solves the problem
Absorbing glucose into the blood by animals
Uptake of glucose from kidney tubules into the blood in animals
Uptake of nitrate ions
Why is cyanide such an effective poison?
Cyanide stops mitochondria from respiring. It also stops active transport.
Explain the steps for the dandelion experiment
- Cut the dandelion stalk into sections and then strips
2. Place the pieces of dandelion into the water and salt water simultaneously
What is passive?
Passive is the opposite of active: happening without the need for additional energy
What is active transport?
Active transport is the transfer of molecules across a cell membrane, against their concentration gradient using energy from cell respiration
What happens to the rate of diffusion and osmosis across a membrane?
It increases with concentration gradient, temperature and surface area
What does the cell wall surrounding plant cells do?
It prevents turgid cells from bursting, so turgid cells support the plant
