Homework #8 Biology 211

Part B - Fungal morphology and physiology The following statements describe something about the body structures or functions of fungi. Identify those statements that are correct. Select all that apply.

-Some fungi secrete digestive enzymes into the environment and then absorb the digested nutrients. -All fungi are heterotrophs; some species live as decomposers and others as symbionts. -Mycelia are made up of small-diameter hyphae that form an interwoven mass, providing more surface area for nutrient absorption. -Some fungi can grow as either filamentous or single-celled forms.

Cup fungi are in the phylum _____.

Ascomycota: Cup fungi are a type of sac fungus.

Which of the following is a synapomorphy that defines all green algae and land plants? See Section 28.2 (Page 565) .

Chloroplasts containing chlorophylls a and b This is the key trait that resulted in a massive adaptive radiation.

Part C - Ecological interactions of fungi Most fungi are decomposers; they recycle the nutrients from nonliving organic matter. Other fungi are specialized to live in symbiotic relationships with other organisms. Some fungi live as parasites and others as mutualists. Most plants, in fact, could not survive and grow without their fungal partner. This table lists some examples of different fungal strategies for obtaining nutrients. Sort the following fungi based on whether they are decomposers, mutualists, or parasites. Drag each item to the appropriate bin.

Decomposer: -fungi in asso. with a fallen log -fungi in asso. with a dead rabbit -coprophilous fungi Mutualist: -mycorrhizal fungi on pine tree roots -fungi in the family Lepiotaceae Parasite: -Trichophyton spp. -Cryphonectria parasitica -Cordyceps spp. -Septobasidium spp. and an individual scale insect infeted by fungal hyphae

What impact will the loss of land plants have on the soil? See Section 28.1 (Page 563) .

Decrease soil stability Soils are held together well via the roots systems of terrestrial plants.

Why is it more difficult to treat fungal infections than bacterial infections in humans?

Fungal and animal cells and proteins are similar. Thus, drugs that disrupt fungal cell or protein function may also disrupt human cell or protein function.

How do fungi acquire nutrients? See Chapter 29 (Page 590) .

Fungi externally digest and absorb nutrients from other organisms, both living or dead.

Fungi produce _____ spores.

Haploid

Your aunt is a mycologist. She discovers a new species of mushroom that is mycorrhizal. Which of the following is true?

It shares nutrients with a host plant.

Basidia produce spores by a process known as _____.

Meiosis

Plants evolved from green algae approximately _____ million years ago.

Plants evolved from green algae about 475 million years ago.

It has been hypothesized that fungi and plants have a mutualistic relationship because plants make sugars available for the fungi's use. What is the best evidence in support of this hypothesis?

Radioactively labeled sugars produced by plants eventually show up in the fungi with which they are associated.

In most fungi, karyogamy does NOT immediately follow plasmogamy, which consequently ________.

Results in heterokaryotic or potentially even dikaryotic cells

Fungi that absorb nutrients from decaying plant matter are called _____.

Saprobes

Fungi release digestive enzymes into their _____.

Surroundings Fungi then absorb the digested nutrients.

Plasmogamy is _____.

The fusion of hyphae.

A raccoon eats a morel mushroom in the Illinois woods. Which of the following is true?

This fungus is still alive and able to reproduce.

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

Two or more genetically distinct nuclei exist within a single mycelium.

Part A - Structure of multicellular fungi This diagram shows the structure of a multicellular fungus, with an expanded view of two types of hyphae. Identify the structures and determine which hypha is septate and which is coenocytic. (Note that although this diagram shows the two types of hyphae, a fungus can have either one type or the other, but not both.) Drag the labels to their appropriate locations on the diagram of the fungus and hyphae below.

a. mycelium b. pore c. septum d. septate hypha e. coenocytic hypha

Chemicals, secreted by soil fungi, which inhibit the growth of bacteria, are known as _____.

antibiotics

The living plants that are most similar to the first plants to bear gametangia are the _____.

bryophytes Bryophytes, such as mosses, are the extant plants that are most similar to the first plants to bear gametangia.

This is an image of a(n) _____.

charophycean. Charophyceans are the green algae most closely related to plants.

You are a mycologist interested in studying Sparassis crispa, also known as the cauliflower fungus. Where are you most likely to find this species?

coniferous forest

Most fungi are _____.

decomposers -Fungi obtain nutrients from nonliving organic matter.

Which of the following was a challenge to the survival of the first land plants?

desiccation (the state of extreme dryness)

Karyogamy produces a _____.

diploid zygote. Karyogamy is the fusion of nuclei

_____ are an example of seedless vascular plants.

ferns

When you eat a mushroom, which of the following are you eating?

fruiting body

Angiosperms are most closely related to _____.

gymnosperms The branching pattern of the phylogenetic tree in the activity indicates that angiosperms are most closely related to gymnosperms.

Which of these was the dominant plant group at the time that dinosaurs were the dominant animals?

gymnosperms Both gymnosperms and dinosaurs were dominant during the Mesozoic.

In plants, which of the following are produced by meiosis?

haploid spores

The ___________ gametophyte stage produces gametes (eggs and sperm) by __________. See Section 28.3 (Page 569) .

haploid; mitosis Since the gametophyte is haploid, it cannot produce gametes by meiosis.

Long, branching fungal filaments are called _____.

hyphae

Conidia produced by a single function are genetically ________. See Section 29.2 (Page 594) .

identical because they are produced asexually, they are clones.

Archegonia ________.

may contain sporophyte embryos

Mushrooms depend on which of the following to spread?

mycelia

It has been hypothesized that fungi and plants have a mutualistic relationship because fungi provide critical nitrogen for the plants' use. How do we know this happens? In experiments using radioactively labeled ________.

nitrogen, plants acquired more radioactive nitrogen when they were associated with fungi

What is the major distinguishing characteristic of fungi?

nutrient acquisition via external digestion

Experiments with isotopes used as tracers showed that some fungi _____. See Section 29.3 (Page 599) .

obtain sugars from plants in exchange for phosphorus, nitrogen, and other soil nutrients In some cases, as much as 20 percent of the sugar molecules produced by a plant are transferred to symbiotic fungi.

Plants synthesize toxic compounds to repel insects, deer, or other herbivores. These compounds have also become important for the development of new _____. See Section 28.1 (Page 563) .

pharmaceuticals Approximately 25 percent of the prescriptions written in the United States each year include at least one compound or substance derived from plants.

Which of these contains two haploid nuclei?

the heterokaryotic stage of the fungal life cycle. The heterokaryotic stage is produced by plasmogamy.