Chapter 31: Fungi(1)

Question 1

Explain fungi nutrition and how they breakdown food.

Answer 1

• Fungi are heterotrophs and absorb nutrients from outside of their bodies
• Fungi use enzymes to break down a large variety of complex molecules into smaller organic compounds

Question 2

What are the diverse forms of fungi?

Answer 2

Fungi exhibit diverse lifestyles
– decomposers
– parasites
– mutualists

Question 3

Explain the structure of fungi.

Answer 3

The most common body structures are:
– multicellular filaments and
– single cells (yeasts)

• Some species grow as either filaments or yeasts; others grow as both

Question 4

Explain the body structures of fungi and its function

Answer 4

• Fungi consist of mycelia, networks of branched hyphae adapted for absorption
• Mycelia allows fungus to invade better areas nutritionally and also provides larger surface area for water and nutrient absorption

Question 5

Fungal cell walls contain ______

Answer 5

Chitin

Question 6

What is septa? Which fungi lacks septa?

Answer 6

Most fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement of organelles.

Coenocytic fungi lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei.

Question 7

What is mycorrhiza and what kind of specialized hyphae do they have?

Answer 7

Mycorrhizae are mutually beneficial
relationships between fungi and plant
roots

• Haustoria – specialized hyphae that
  allow mycorrhizae to penetrate
  tissues of their host

Question 8

What is ectomycorrhizal fungi?

Answer 8

Ectomycorrhizal fungi form sheaths of hyphae over a root and also grow into extracellular spaces of the root cortex

Question 9

What kind of hyphae is present in arbuscular mycorrhizal fungi?

Answer 9

Arbuscular mycorrhizal fungi extend hyphae through the cell walls of root cells

Question 10

How does fungi communicate their mating type?

Answer 10

Fungi use sexual signaling molecules called pheromones to communicate their mating type

Question 11

Define plasmogamy.

Answer 11

Plasmogamy is the union of cytoplasm from two parent mycelia

Question 12

Define heterokaryon.

Answer 12

In most fungi, haploid nuclei from each parent do not fuse right away; they coexist in the mycelium, called a heterokaryon

Question 13

What does dikaryotic mean?

Answer 13

In some fungi, haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic

Question 14

What is karyogamy?

Answer 14

Karyogamy – nuclear fusion of haploid nuclei from the two parents to form a diploid zygote

The period between plasmogamy and karyogamy varies (hours to centuries)

Question 15

How do fungi produce genetic variation?

Answer 15

The paired processes of karyogamy and meiosis produce genetic variation

Question 16

How do fungi reproduce asexually?

Answer 16

Many fungi can reproduce asexually

Moulds produce haploid spores by mitosis and form visible mycelia

Question 17

How does yeast reproduce?

Answer 17

Yeasts reproduce asexually
by

– simple cell division and
– pinching of “bud cells” from
a parent cell

Question 18

What are the diverse groups in fungi?

Answer 18

1. Basidiomycetes
2. Ascomycetes
3. Gloromycetes
4. zygomycetes
5. Chytrids

Question 19

Explain chytrids

Answer 19

• They can be decomposers, parasites, or mutualists
• Molecular evidence supports the hypothesis that chytrids diverged early in fungal evolution
• They have flagellated spores, called zoospores

Question 20

Explain zygomycetes.

Answer 20

They include fast-growing moulds, parasites, and commensal symbionts
– Ex: black bread mould (Rhizopus stolonifer)
* Its hyphae are coenocytic
* Asexual sporangia produce haploid spore