Diffusion, osmosis and active transport in living organisms Flashcards
What is diffusion?
The movement of particles in a solvent from an area of high concentration to an area of low concentration.
Why does diffusion occur?
The random movement of particles causes them to move around and after some time, there will be an even distribution of particles across the solvent.
How do you increase rate of diffusion?
-Large difference in concentration between 2 areas: More particles are moving towards the area of low concentration than away.
-High temperature: particles move more quickly and random movement speeds up.
What is net movement?
Particles going in - particles going out = net movement
Where does diffusion happen in living organisms?
Dissolved substances move between cells across the cell membrane
What is moved across the cell membrane by diffusion?
-Simple sugars like glucose.
-Gases like oxygen and carbon dioxide.
-Waste products like urea from your liver cells.
How does the blood use diffusion?
-Oxygen in the lungs enters through the red blood cells’ cell membrane by diffusion. The oxygen moves down a concentration gradient from high to low concentration.
-Oxygen moves down a concentration gradient from the blood cells into the body where it’s needed.
-Carbon dioxide moves from the body into the blood and then into the lungs both down a concentration gradient.
What is a concentration gradient?
The process of particles moving through a solution from an area of high concentration to an area of low concentration.
How are cells adapted to optimise diffusion?
-Higher surface area by folding membrane
What is a type of membrane that only allows certain types of particles to cross.
A partially permeable membrane
What is osmosis?
When particles move across a partially permeable membrane from a dilute solution to a concentrated solution
What is a isotonic solution?
The concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions maintaining cell size
What is a hypertonic solution?
The solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to plasmolyze (shrivel up)
What is a hypotonic solution?
the solution has a lower solute concentration than the cell so water moves into the cell causing plant cells to swell and animal cells to swell and burst
What happens when a cell uses up water in its reaction?
The cytoplasm becomes more concentrated than the surrounding fluid (hypotonic) and water enters the cell by osmosis.
