Problem 9 - Campbell Biology Concepts & Connections

Question

Which of the following groups is made up exclusively of fungi that form symbioses with plant roots? a. ascomycetes b. basidiomycetes c. glomeromycetes d. zygomycetes

Step-by-Step Solution

Answer

c. glomeromycetes

Step 1: Identify the Definitions

To solve this question, first understand the definitions and roles of each fungal group. Knowing which fungi form symbiotic relationships with plant roots will help identify the correct answer.

Step 2: Review Ascomycetes

Ascomycetes are a group of fungi known for their sac-like structures which include molds, yeasts, and morels. While some can form symbiotic relationships like lichens, they are not exclusively known for forming symbioses with plant roots.

Step 3: Review Basidiomycetes

Basidiomycetes include fungi such as mushrooms, puffballs, and shelf fungi. They can also form symbiotic relationships, such as mycorrhizae, but this is not a characteristic that is exclusive to them.

Step 4: Review Glomeromycetes

Glomeromycetes are a group of fungi that almost exclusively form arbuscular mycorrhizas, which are crucial for plant root symbiosis. This makes them a strong candidate for fungi that form symbiosis with plant roots.

Step 5: Review Zygomycetes

Zygomycetes are primarily known for forming bread molds and other similar fungi. While they can sometimes form symbiotic relationships, this is not their defining characteristic.

Step 6: Conclusion

From steps 1 to 5, it is clear that glomeromycetes (c) are the only group that exclusively form symbioses with plant roots, specifically through arbuscular mycorrhizae.

Key Concepts

headline of the respective core concept

Glomeromycetes are a unique group of fungi that specialize in forming symbiotic relationships with plant roots. These fungi are almost exclusively known for creating arbuscular mycorrhizas, a type of mutualistic association crucial for the health and nutrient uptake of many plants. Unlike other fungal groups, which may occasionally form symbioses with plants, glomeromycetes are particularly adapted to this role. They penetrate the root cells of plants and form arbuscular structures, which can efficiently transfer nutrients like phosphorus to the plant. This specialized relationship makes glomeromycetes vital to many ecosystems and agricultural settings.

headline of the respective core concept

Arbuscular mycorrhizae (AM) are specialized symbiotic structures formed between glomeromycete fungi and the roots of most terrestrial plants. In this symbiosis, the fungus enhances the plant's nutrient and water absorption capabilities, while the plant provides carbohydrates to the fungus. This relationship is incredibly beneficial and ubiquitous, found in about 80% of vascular plants. The arbuscles inside the root cells increase the surface area for nutrient exchange. Homes and gardens often benefit from this symbiosis, as it enhances plant growth and health.

headline of the respective core concept

Fungal groups include several major divisions like ascomycetes, basidiomycetes, and zygomycetes, each with distinct characteristics. Ascomycetes are known for their sac-like structures, producing molds, yeasts, and morels. Basidiomycetes include mushrooms and puffballs, recognized for their spore-bearing structures called basidia. Zygomycetes are primarily associated with bread molds and decomposers. While these groups can form various relationships with plants and other organisms, the glomeromycetes are unique in their exclusive formation of arbuscular mycorrhizae for symbiosis with plant roots.