Biology
Ecological factors and relationships between organisms
Factors affecting an organism fall into three groups:
- Abiotic: temperature, light, moisture.
- Biotic: interactions among living organisms.
- Anthropogenic: human activity.
The most favorable level of a factor for an organism: the optimum.
Liebig's law: an organism's life is limited by the factor that is at a minimum.
Relationships
| Relationship | A | B |
|---|---|---|
| Mutualism | benefit | benefit |
| Commensalism | benefit | neutral (0) |
| Parasitism | benefit | harm |
| Predation | benefit | harm |
| Competition | harm | harm |
- Mutualism: beneficial to both sides. For example, a legume plant and nodule bacteria.
- Commensalism: one side benefits, the other is unaffected.
- Predation, parasitism, and competition.
Key facts
- Lichen: a symbiosis of a fungus and an alga. Mycorrhiza: a symbiosis of a fungus and a plant root.
- An example of commensalism: sharks and remora fish.
- Competition: intraspecific (between individuals of the same species) and interspecific.
- Photoperiodism: an organism's adaptation to day length. Anabiosis: the halting of vital processes.
- The parasite benefits, the host is harmed.