Symbiosis

Definition

Symbiosis is a close and long-term biological interaction between two different biological organisms, which can be mutualistic, commensalistic, or parasitic. It plays a crucial role in the survival and evolution of many prokaryotic species.

5 Must Know Facts For Your Next Test

1. Symbiotic relationships are essential for nutrient cycling and energy flow in ecosystems.
2. Mutualistic symbiosis benefits both organisms involved; an example is the relationship between nitrogen-fixing bacteria and leguminous plants.
3. Commensalism involves one organism benefiting while the other is neither helped nor harmed, like certain bacteria on human skin.
4. Parasitic symbiosis harms one organism while benefiting the other, such as pathogenic bacteria causing diseases in hosts.
5. Symbiotic relationships can influence the composition and function of microbiomes within various habitats.

Review Questions

• What are the three main types of symbiotic relationships?
• How does mutualistic symbiosis differ from parasitic symbiosis?
• Give an example of commensalism involving prokaryotes.

Related terms

Microbiome: The collection of microorganisms living in a particular environment, including their genetic material.

Nitrogen Fixation: A process by which certain bacteria convert atmospheric nitrogen into ammonia, which plants can use for growth.

Pathogen: An organism that causes disease in its host.