Ch. 29 - Fungi

Freeman - Biological Science 8th Edition

Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook

Freeman 8th Edition

Ch. 29 - Fungi

Problem 5

Chapter 29, Problem 5

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

Understand the meaning of the Greek root 'ecto,' which means 'outer.' This will help in understanding why ectomycorrhizal fungi are named as such.

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.

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.

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.'

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.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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.

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Related Practice

Textbook Question

Evaluate the following statements about mushrooms. Select True or False for each statement.

T/F A diploid zygote is formed when a male spore fertilizes a female spore.

T/F Haploid spores are formed by meiosis in basidia.

T/F A mushroom is a reproductive structure that consists largely of dikaryotic cells.

T/F Mushrooms are part of the group that also includes bracket fungi, boletes, puffballs, and stinkhorns.

Textbook Question

The hyphae of arbuscular mycorrhizal fungi (AMF) form bushy structures after making contact with the plasma membrane of a root cell. What is the function of these structures?

a. They anchor the fungus inside the root, so the association is more permanent.

b. They increase the surface area available for the transfer of nutrients.

c. They produce toxins that protect the plant cells against herbivores.

d. They break down cellulose and lignin in the plant cell wall.

Textbook Question

What does it mean to say that a hypha is dikaryotic?

a. Two nuclei fuse during sexual reproduction to form a zygote.

b. Two independent nuclei, derived from different individuals, are present in each cell.

c. The nucleus is diploid or polyploid — not haploid.

d. It is extremely highly branched, which increases its surface area and thus absorptive capacity.

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Textbook Question

Explain why fungi that degrade dead plant materials are important to the global carbon cycle. Do you accept the text's statement that, without these fungi, 'Terrestrial environments would be radically different than they are today, and probably much less productive'? Why or why not?

Textbook Question

Evaluate each of the following defects. Which could lead to uncontrolled growth in cancer? Select True or False for each statement. T/FThe overexpression of MPF activity. T/FA nonfunctional Rb protein. T/FThe overexpression of G1 cyclin. T/FA nonfunctional E2F protein.

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Textbook Question

Lignin and cellulose provide rigidity to the cell walls of plants. But in most fungi, chitin performs this role. Why is it logical that most fungi don't have lignin or cellulose in their cell walls?