Rhizobia

Definition

Rhizobia are soil bacteria that form symbiotic relationships with leguminous plants by fixing atmospheric nitrogen into a form that the plants can use. This mutualistic interaction is crucial for plant nutrition and soil fertility.

5 Must Know Facts For Your Next Test

1. Rhizobia fix atmospheric nitrogen (N2) into ammonia (NH3), which plants can absorb and use.
2. They form root nodules on leguminous plants, where the nitrogen fixation process occurs.
3. Rhizobia receive carbohydrates and a protective environment from the host plant in exchange for fixed nitrogen.
4. The relationship between rhizobia and legumes is an example of mutualism, benefiting both organisms involved.
5. Different species of rhizobia are specific to different types of leguminous plants.

Review Questions

• What role do rhizobia play in the nitrogen cycle?
• How do rhizobia benefit from their symbiotic relationship with leguminous plants?
• Why are root nodules important for the process of nitrogen fixation in legumes?

Related terms

Nitrogen Fixation: The process of converting atmospheric nitrogen (N2) into a biologically usable form like ammonia (NH3).

Legume: A type of plant, such as beans or peas, that forms symbiotic relationships with rhizobia to fix nitrogen.

Mutualism:

A type of symbiosis where both organisms involved benefit from the interaction.