Diffusion, Osmosis, Active Transport Flashcards
What is diffusion?
The spreading out of particles from an area of higher concentration to an area of lower concentration.
Where does diffusion take place?
In solutions and gases.
What factors affect the rate of diffusion?
The difference in concentrations (concentration gradient) - the bigger the difference in concentration, the faster the diffusion rate.
Temperature - higher temperature will give a faster diffusion rate.
The surface area of the membrane
What are some of the substances transported in and out of cells by diffusion?
Oxygen and carbon dioxide in gas exchange.
Urea from cells into the blood plasma (for excretion in the kidney).
Explain diffusion across cell membranes.
Particles flow through the cell membrane from where there’s a higher concentration to a lower concentration.
What molecules can diffuse through cell membranes?
Only very small molecules can diffuse through cell membranes - e.g. oxygen, glucose, amino acids, water.
What is osmosis?
The movement of water molecules across a partially permeable membrane from a more concentrated solution to a less concentrated solution.
What is active transport?
Movement of particles against a concentration gradient (from an area of lower concentration to an area of higher concentration) using energy transferred during respiration.
How does active transport work for plants?
It allows minerals to be absorbed by the root hair cell from a very dilute solution in the soil. (Plants require ions for healthy growth.)
How does active transport work in the gut?
Allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. (Sugar molecules are used for respiration.)
