Movement of substances into and out of cells Flashcards
1
Q
Define diffusion
A
- Net movement of particles from an area of high concentration to an area of low concentration
- Down a concentration gradient
2
Q
What factors affect the rate of diffusion?
A
- Concentration gradient
- Surface area to volume ratio
- Diffusion distance
- Temperature
3
Q
What factors increase the rate of diffusion?
A
- Steep concentration gradient
- High surface area to volume ratio
- Shorter diffusion distance
- Higher temperature due to increased kinetic energy of particles
4
Q
Define active transport
A
- Net movement of particles from an area of low concentration to an area of high concentration
- Requires energy from ATP
5
Q
Give examples of active transport
A
- Root hair cells absorbing mineral ions
- Movement of glucose through the lining of the small intestine
6
Q
Define osmosis
A
- Net movement of water
- From an area of high water potential to low water potential
- Through partially permeable membrane
7
Q
What happens to a plant cell placed in salty solution and why?
A
- Shrinks (flaccid)
- Cell membrane pulls away from cell wall (plasmolysis)
- Because higher water potential in cell compared with surrounding solution so water leaves the
cell by osmosis
8
Q
What happens to a plant cell placed in pure water and why?
A
- Swells (turgid)
- Because higher water potential in surrounding solution compared with inside the cell so water
enters the cell by osmosis - Cell wall prevents bursting
9
Q
What happens to an animal cell placed in pure water and why?
A
- Bursts
- Because higher water potential in surrounding solution compared with inside the cell so water
enters the cell by osmosis - No cell wall so bursts
10
Q
Examples of large surface area to volume ratios for movement of substances
A
- Alveoli in lungs for absorption of oxygen
- Villi in small intestine for absorption of soluble products of digestion
- Root hair cells for absorption of mineral ions
