Diffusion and Active Transport
- Created by: India.02
- Created on: 11-05-19 19:12
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- Diffusion and Active Transport
- Diffusion
- Gradual movement of particles from an area of high concentration to an area of low concentration
- Happens in solutions and gases - these particles are free to move randomly
- The bigger the concentration gradient (difference in concentration) - the faster the diffusion rate
- Higher temperature will give a faster diffusion rate because the particles will have more energy and will move around faster
- Cell Membranes
- Dissolved substances can move in and out of cells by diffusion, through the cell membrane
- Particles flow through the cell membrane from where the concentrations highest to where the concentration is lowest
- Particles move randomly but if there are a lot more particles on one side of the membrane, there will be a net movement from that side (overall)
- Larger the surface area of the membrane, the faster the diffusion rate - more particles can pass through at once
- Active Transport
- We need it
- Used in the gut when there is a low concentration of nutrients, but a higher concentration in the blood
- When there is a higher concentration of glucose and amino acids in the gut, they diffuse naturally into the gut
- BUT - sometimes there is a lower concentration of nutrients in the gut than there is in the gut
- Concentration gradient is the wrong way - low to high concentration
- Allows nutrients to be taken back into the blood despite the fact that the concentration gradient is the wrong way
- Glucose can also be taken into the bloodstream when its concentration in the blood is already higher than in the gut - transpired to cells for respiration
- Root Hair Cells
- Each branch of a root will be covered in microscopic hairs that stick into the soil
- Gives large surface area for absorbing water and mineral ions from soil - needed for healthy growth
- Concentration of minerals is usually higher in the root hair cells than the soil around them - root hair cells can't use diffusion to take up minerals
- Gives large surface area for absorbing water and mineral ions from soil - needed for healthy growth
- Active transport allows the plant to absorb minerals from a very dilute solution, against a concentration gradient - essential for growth but needs energy from respiration to work
- Each branch of a root will be covered in microscopic hairs that stick into the soil
- We need it
- Diffusion
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