Chapter 31: Fungi

Question 1

Fungi nutrition

Answer 1

• Feed by absorption; secrete hydrolytic enzymes into surrounding to break down complex molecules
• Parasitic fungi: Absorb nutrients from cells of living hosts (some pathogenic)

Question 2

Body structure

Answer 2

• Most common is multicellular filaments/single cell

- Multicellular comprised of hyphae (network of tiny filaments), cell walls made of chitin

Question 3

Septate hypha

Answer 3

• Cell walls separate nuclei

Question 4

• Coenocytic fungi

Answer 4

• Continuous cytoplasmic mass with thousands of nuclei

Question 5

Mycelium

Answer 5

• Infiltrate material on which the fungus feeds

Question 6

Specialized Hyphae

Answer 6

• Haustoria: Fungi use to extract nutrients from plant hosts
• Mycorrhizae: Means fungus roots; improve delivery of phosphate ions and other minerals to plants
• Ectomycorrhizal fungi: Form sheaths of hyphae over the surface of a root and typically grow into extracellular spaces of root cortex
• Arbuscular mycorrhizal fungi: Extend branching hyphae through root cell wall and into tubes formed by invagination

Question 7

Sexual Reproduction

Answer 7

• Nuclei of fungal hyphae and spores of most fungi are haploid
• Sexual reproduction often begins when hyphae from two mycelia release sexual signaling molecules (called pheromones)
• Cytoplasmic fusion (plasmogamy)
• Nuclear fusion (karyogamy)
• Intervening heterokaryotic stage in which cells have haploid nuclei from two parents
• Diploid cells resulting from karyogamy are short-lived and undergo meiosis (produce genetically diverse haploid spores)

Question 8

Ancestor of fungi

Answer 8

• Aquatic, sing-celled flagellated protists

- Fungi were some of the first colonizers of land; probably symbionts with first land plants

Question 9

Chytrids

Answer 9

• Group of fungi with flagellated spores, include some basal lineages

Question 10

Zygomycota

Answer 10

• resistant zygosporangium as sexual stage

Question 11

Glomeromycota

Answer 11

• Arbuscular mycorrhizae formed with plants

Question 12

Asomycota

Answer 12

• Sexual spores borne internally in sacs calls asci

- Vast numbers of asexual spores produced

Question 13

Basidiomycota

Answer 13

• Elaborate fruiting body containing many basidia that produce sexual spores

Question 14

Fungi importance in ecosystem

Answer 14

• Key role in nutrient cycling
• Important in ecological interaction
• Human welfare (antibiotics and food)

Question 15

Lichen

Answer 15

Highly integrated symbiotic associations of fungi and algae or cyanobacteria

Question 16

Asexual reproduction

Answer 16

• Grow filamentous fungi to produce haploid spores
• Yeasts, molds
• Deuteromycetes: Fungi lacking sexual reproduction

Question 17

Fungi as Mutualists

Answer 17

• All plant species studied harbor symbiotic endophytes (fungi that live inside leaves or other plant parts without causing harm)
• Most are ascomycetes

Question 18

Soredia

Answer 18

Small clusters of hyphae with embedded algae; many of these reproduce sexually