C4.1.12 Mutualism as an interspecific relationship that benefits both species Notes

Mutualism: A Relationship That Benefits Both Species

1. Mutualism plays a crucial role in ecosystem stability, enhancing survival, growth, and reproduction.

Root Nodules in Fabaceae (Legume Family)

1. Most plants cannot use atmospheric nitrogen (N2) directly.
2. Legumes (e.g., peas, beans, and clover) form a mutualistic relationship with nitrogen-fixing bacteria (Rhizobium) to overcome this limitation.

How It Works

1. Root Nodule Formation: Legumes develop root nodules, which provide a habitat for Rhizobium bacteria.
2. Nitrogen Fixation: Rhizobium converts atmospheric N2 into ammonium (NH4), which plants can absorb and use for growth.

Benefits to Both Organisms

1. Legumes: Receive a steady supply of nitrogen, boosting growth and survival in nitrogen-poor soils.
2. Rhizobium: Gains a protected environment inside the root nodules and receives sugars and nutrients from the plant for energy.

Mycorrhizae in Orchidaceae (Orchid Family)

1. Orchids cannot germinate and survive alone in the wild.
2. Instead, they rely on a mycorrhizal relationship with fungi, particularly in nutrient-poor environments.

How It Works

1. Fungal Hyphae Penetration: The fungus grows into the orchid’s roots, forming a network around root cells.
2. Nutrient Exchange: The fungus absorbs nutrients (nitrogen, phosphorus, water) from the soil and transfers them to the orchid.

Benefits to Both Organisms

1. Orchids: Gain essential nutrients and water, crucial for germination and early development.
2. Fungi: Obtain carbon compounds (sugars) from the orchid once it starts photosynthesis.

Zooxanthellae in Hard Corals

Hard corals form coral reefs, but they cannot survive without zooxanthellae, tiny photosynthetic algae that live inside their cells.

How It Works

1. Symbiotic Living: Zooxanthellae live within coral tissue, performing photosynthesis.
2. Nutrient Exchange: The algae provide the coral with organic compounds (glucose, oxygen) and the coral supplies algae with carbon dioxide and nutrients from waste.

Benefits to Both Organisms

1. Corals: Receive up to 90% of their energy from the algae, using the energy to build calcium carbonate skeletons to form coral reefs.
2. Zooxanthellae: Gains a protected environment inside coral cells and access to nutrients from coral waste.

Why Mutualism Matters

1. Ecosystem Stability: Mutualism enhances biodiversity and nutrient cycling.
2. Agriculture & Conservation: Understanding mutualism helps sustainable farming (e.g., legumes & nitrogen-fixing bacteria) and reef conservation.