The Greek root ecto means 'outer.' Why are ectomycorrhizal fungi, or EMF, aptly named?
a. Their hyphae form tree-like branching structures inside plant cell walls.
b. They are mutualistic.
c. Their hyphae form dense mats that envelop roots but do not penetrate the cell walls.
d. They transfer nitrogen from outside their plant hosts to the interior.

Verified step by step guidance

1. Understand the meaning of the Greek root 'ecto,' which means 'outer.' This will help in understanding why ectomycorrhizal fungi are named as such.
2. Ectomycorrhizal fungi (EMF) are a type of fungi that form symbiotic relationships with the roots of plants. The key characteristic of these fungi is how they interact with the plant roots.
3. Consider the structure of ectomycorrhizal fungi: their hyphae form a dense network around the plant roots. This network is external to the plant root cells, meaning it does not penetrate the cell walls.
4. Compare the options given: Option c states that the hyphae form dense mats that envelop roots but do not penetrate the cell walls, which aligns with the meaning of 'ecto' as 'outer.'
5. Conclude that the name 'ectomycorrhizal' is appropriate because it describes the external positioning of the fungal hyphae relative to the plant root cells, as indicated in option c.

Key Concepts

Ectomycorrhizal Fungi

Ectomycorrhizal fungi (EMF) are a type of mycorrhiza that form symbiotic relationships with the roots of certain plants. The term 'ecto' refers to their characteristic of forming structures on the outer surface of plant roots, enveloping them without penetrating the cell walls. This external association is crucial for nutrient exchange between the fungi and the host plant.

Mutualism

Mutualism is a type of symbiotic relationship where both parties involved benefit from the association. In the case of ectomycorrhizal fungi, the fungi receive carbohydrates from the plant, while the plant benefits from enhanced nutrient uptake, particularly phosphorus and nitrogen, facilitated by the fungi's extensive hyphal network.

Hyphae

Hyphae are the thread-like structures that make up the body of fungi. In ectomycorrhizal fungi, hyphae form dense mats around plant roots, increasing the surface area for nutrient absorption. These structures are crucial for the fungi's ability to transfer nutrients from the soil to the plant, while remaining outside the plant's cell walls, aligning with the 'ecto' characteristic.