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. Step 1: Understand the question. The question is asking why the term 'ectomycorrhizal fungi' is appropriate based on the meaning of the Greek root 'ecto,' which means 'outer.'
2. Step 2: Review the answer choices. Each choice describes a characteristic of ectomycorrhizal fungi, but we need to find the one that relates to the 'outer' meaning of 'ecto.'
3. Step 3: Evaluate each choice. Choice a describes an internal structure, so it doesn't fit. Choice b describes a type of relationship, not a location, so it doesn't fit. Choice d describes a process, not a location, so it doesn't fit.
4. Step 4: Choice c describes the hyphae of ectomycorrhizal fungi forming dense mats that envelop roots but do not penetrate the cell walls. This fits with the 'outer' meaning of 'ecto,' because the fungi are on the outside of the roots.
5. Step 5: Therefore, the correct answer is c. Ectomycorrhizal fungi are aptly named because their hyphae form dense mats that envelop roots but do not penetrate the cell walls, aligning with the 'outer' meaning of 'ecto.'

Key Concepts

Ectomycorrhizal Fungi

Ectomycorrhizal fungi (EMF) are a type of fungi that form symbiotic relationships with the roots of many trees and shrubs. They are characterized by their ability to envelop the root tips with a dense network of hyphae, creating a protective sheath. This relationship enhances nutrient and water absorption for the plant while providing the fungi with carbohydrates produced through photosynthesis.

Mutualism

Mutualism is a type of symbiotic relationship where both organisms involved benefit from the interaction. In the case of ectomycorrhizal fungi, the fungi receive organic carbon from the plant, while the plant gains improved access to nutrients, particularly phosphorus and nitrogen, from the soil. This mutualistic relationship is crucial for the health and growth of many forest ecosystems.

Hyphal Structure

Hyphae are the filamentous structures that make up the body of fungi. In ectomycorrhizal fungi, the hyphae form a dense mat around the roots of plants, which helps in nutrient absorption. Unlike endomycorrhizal fungi, which penetrate plant cell walls, ectomycorrhizal hyphae remain external, allowing them to efficiently absorb nutrients from the soil while maintaining a protective barrier around the roots.