Symbiosis and Mutualism notes
SYMBIOSIS
- Definition: Close and often long-term interactions between different biological species.
- Symbiotic relationships can be categorized into three types:
- Mutualistic: Both the symbiont and host benefit.
- Commensal: The symbiont benefits with little effect on the host.
- Parasitic: The symbiont benefits at the detriment of the host.
Mutualism
Mycorrhizae
- Meaning: "Fungus-root"
- Description: A common and widespread symbiosis between terrestrial plants and fungi that colonize their roots.
- Prevalence: Occurs in about 80% of all plant species.
- Importance: Essential for many plants in low-nutrient environments.
- Reason: Roots alone are incapable of absorbing sufficient essential minerals like phosphorus.
- Benefit to Fungi: Fungi cannot photosynthesize and thus rely on plants for food.
Lichenism
- Description: Lichens are composite organisms made up of a symbiotic association between a fungus and a photosynthetic partner (usually a green alga or cyanobacterium).
- Environments: Found in some of the most extreme environments on Earth, such as arctic tundra, hot deserts, rocky coasts, and toxic slag heaps.
- Characteristics: Widespread and can be long-lived but are vulnerable to environmental disturbances that allow for assessment of air pollution effects.
- Uses: Lichens have been applied in making dyes, perfumes, and have a history of use in traditional medicines.
Nodule bacteria (Nitrogen-fixing bacteria)
- Examples: Legumes and certain other plants coexist with Rhizobium bacteria, which form small nodules on their roots.
- Process: Carry out nitrogen fixation, the conversion of nitrogen gas () into ammonia ().
- Importance of Nitrogen: An essential element required by all organisms, but plants cannot utilize it in gaseous form.
- Benefit to Plants: Plants can readily use ammonia produced by these bacteria, enhancing their growth.
- Benefit to Bacteria: The host plant provides these bacteria a carbohydrate energy source.