Topic 3 Flashcards
(20 cards)
Define diffusion
The net movement of molecules from an area of high concentration to an area of low concentration down their concentration gradient
Where does the energy for the movement of particles in diffusion come from
From the kinetic energy of the particles that causes them to move in random directions
Why is the diffusion of gases important?
It allows for gas exchange in organisms to provide useful gases for processes like respiration and to remove waste gases
How does temperature affect the rate of diffusion?
As the temperature increases, so does the rate of diffusion as the particles have more kinetic energy and move faster
How does the concentration gradient affect the rate of diffusion?
The greater the concentration gradient, the faster the rate of diffusion
How does the surface area of the membrane affect the rate of diffusion?
As the surface area increases so does the rate of diffusion as there is more space for the particles to move through
How does the diffusion distance affect the diffusion rate?
The larger the diffusion distance, the slower the rate of diffusion as the particles have further to move
Why is water important in the body?
Transport, digestion and excretion.
Define osmosis
The net movement of water molecules from a high water potential to a low water potential down their water potential gradient across a partially permeable membrane
What happens if you place an animal cell in a solution with high water potential?
There is a net movement of water into the cell which causes the animal cell to burst (lysis)
What happens if you place a plant cell in a solution of high water potential?
There is a net movement of water into the cell which causes the plant cell to become turgid
What happens if you place an animal cell in a solution of low water potential?
There is a net movement of water out of the cell which causes the animal cell to shrink (crenate)
What happens if you place a plant cell in a solution of low water potential?
There is a net movement of water out of the cell which causes the plant cell to become plasmolysed
What happens if you put a cell in a solution of the same water potential?
There is no net movement of water in or out of the cell
How is a plant cell supported?
Water within the vacuole creates pressure which supports the cell. The cell wall also provides support.
Explain how the water in plant cells supports them
The water creates turgor pressure which pushes the cell membrane against the cell wall
Define active transport
The movement of molecules from a low concentration to a high concentration against their concentration gradient using energy from respiration
Give one use of active transport in humans
Uptake of minerals and nutrients in the small intestine. Reabsorption in the kidney
Give one use of active transport in plants
Uptake of minerals into root hair cells
Explain how active transport involves proteins
Carrier proteins move substances from one side of the membrane to the other using energy
