Comparing Diffusion, Osmosis and Active transport
| Diffusion | Osmosis | Active Transport | |
|---|---|---|---|
| Definition | Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration. | Osmosis is the diffusion of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane. | Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). |
| Additional energy needed | No | No | Yes |
| Moves down or against a concentration gradient | Down concentration gradient | Down concentration gradient | Against concentration gradient |
| Moves which substance(s) | Oxygen, Urea, carbon dioxide or glucose | Water only | Glucose, mineral ions, amino acids |
| Membrane needed | Sometimes a membrane is present, but it is not always needed | Yes, partially permeable membrane | Yes with carrier proteins |
Factors affecting the rate of photosynthesis
Measuring & calculating rates of photosynthesis
Inverse square law and photosynthesis
Economics of enhancing the conditions in greenhouses
Investigating the effect of light intensity on the rate of photosynthesis
Data analysis and nervous system
The effect of a factor on human reaction time
Controlling blood glucose concentration
Regulating water and nitrogen levels in the body.
Hormones and human reproduction
Using hormones to treat infertility
Control and coordination in plants using hormones
Investigating the effect of light or gravity on the growth of newly germinated seedlings