Movement of substances in and out of cells Flashcards
What are the three movements of substances in and out of cells?
- Diffusion
- Osmosis
- Active transport
What is diffusion?
The net movement of particles from an area of high concentration to an area of lower concentration until a uniform concentration is achieved
Why does diffusion happen in both liquids and gases but not solids?
The particles in these substances are free to move randomly
The bigger the different in concentration in diffusion….
The faster the rate of diffusion
What type of molecules can diffuse through cell membranes?
Small molecules like glucose, amino acids, water and oxygen. Big molecules like starch and protein cant fit through!
Particles in a cell membrane move from an area of…
Higher concentration to an area of lower concentration
If there are more particles on one side of the membrane…
Theres a net movement from that side
What is osmosis?
The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to an area of lower concentration until a uniform water concentration is achieved.
Is osmosis a type of diffusion?
Yes
What is a partially permeable membrane?
A membrane with lots of very small holes in it - stops big molecules flowing through
Why can water molecules flow both ways through the membrane is osmosis?
Because the water molecules move around randomly all the time
If there is a net flow of water into a region with fewer water molecules in osmosis…
That solution becomes more dilute as the water tries to even up the concentration on both sides
What does the tissue fluid around our cells contain?
Water, oxygen and glucose that is squeezed out of the blood capillaries to supply the cell with everything they need.
If a cell is short of water…
It becomes concentrated - the solution outside is more dilute so water moves into the cell by osmosis
If a cell has lots of water…
The solution inside is more dilute - water is drawn out of the cell into the fluid outside by osmosis
What are plants supported by?
Turgid cells
When a plant is well watered…
The cells will draw water in by osmosis, and become plump and swollen (turgid)
What is turgid pressure?
The contents of the cell pushing against the cell wall supporting the plant tissue
What happens to a plant if theres no water in the soil?
The plant starts to wilt (droop) - the cells loose water therefore loose turgid pressure making them flaccid
Why doesn’t a plant totally lose its shape when it becomes flaccid?
The inelastic cell wall keeps things in position - it droops just a bit
What are plants supported by?
Turgid cells
When a plant is well watered…
The cells will draw water in by osmosis, and become plump and swollen (turgid)
What is turgid pressure?
The contents of the cell pushing against the cell wall supporting the plant tissue
What happens to a plant if theres no water in the soil?
The plant starts to wilt (droop) - the cells loose water therefore loose turgid pressure making them flaccid
