Unit 2- Fungi and plants

What role do fungi play in ecosystems?

significant decomposers and recyclers on Earth.

What type of digestion do fungi use?

extracellular

What are the two types of nutritional strategies employed by fungi?

saprobes (dead matter) or symbionts (living matter)

What is the main component of fungal cell walls?

Chitin

What is the thallus in fungi?

the body of the fungal organism.

What are hyphae in fungi?

the filaments that make up the thallus/mycelium of fungi.

What is the difference between septate and coenocytic hyphae?

Septate hyphae have cell walls that partition cells, while coenocytic hyphae do not.

What is haustoria in the context of fungi?

specialized hyphae that release exoenzymes for extracellular digestion.

What does karyogamy refer to in fungal reproduction?

the fusion of nuclei that occurs after plasmogamy in fungal reproduction.

What is a heterokaryon in fungi?

cell condition where two haploid nuclei from different individuals coexist.

What is the Phylum Zygomycota known for?

air-dispersed spores and coenocytic hyphae.

Name a representative organism of Phylum Ascomycota.

Peziza

What type of fungi is Penicillium known for producing?

the antibiotic Penicillin

What are lichens?

mutualistic associations between fungi and algae or cyanobacteria.

What important role do mycorrhizae play in plant health?

enhance water and mineral uptake by plant roots.

What are the major characteristics of kingdom Plantae?

photosynthetic, autotrophic, and have cellulose-based cell walls.

What is the process of fertilization in plants called?

Syngamy.

What is heterospory in plants?

sporophyte produces two kinds of spores: megaspores (for eggs) and microspores (for sperm).

Identify a non-vascular plant.

Mosses/Phylum Bryophyta

Which plant division includes ferns?

Phylum Pterophyta

What is a distinctive feature of gymnosperms?

known as 'naked-seed' plants that do not produce flowers.

What is the largest group of plants?

Angiosperms, or flowering plants.

What are cotyledons in plant classification?

seed leaves that help classify plants as monocots or dicots.

What is the function of seeds in plants?

protect the dormant embryo and provide surrounding nutrients, serving as dispersal agents.

What adaptations do seed plants have for terrestrial life?

protected gametophytes, pollination for sperm delivery, and seeds for dispersal.

What kind of symbiotic relationships do lichens and mycorrhizae represent?

— are mutualistic relationship between fungi and algae/cyanobacteria, while —- are mutualistic associations between fungi and plant roots.

What process in fungal reproduction involves the fusion of cytoplasm from two parent mycelia?

Plasmogamy

What structural polymer makes up the cell walls of plants?

Cellulose

In plant alternation of generations, what diploid phase produces spores via meiosis?

Sporophyte

In plant alternation of generations, what haploid phase produces gametes via mitosis?

Gametophyte

Which fungal phylum is commonly called club fungi and includes mushrooms and puffballs?

Phylum Basidiomycota

What plant vascular tissue conducts water and dissolved minerals upward from roots?

Xylem

What plant vascular tissue transports sugars and organic nutrients throughout the plant?

Phloem

What microscopic leaf pores regulate gas exchange and water loss in plants?

Stomata

What is Plasmogamy?

The first step in fungal sexual reproduction where the cytoplasm of two haploid (n) cells fuses

while their nuclei remain separate.

What is the Dikaryotic State (n + n)?

A unique fungal transition state where a cell contains two distinct

unfused haploid nuclei originating from different parent strains (a type of heterokaryon).

What is Karyogamy

and when does it occur?

The fusion of two haploid nuclei into a single diploid (2n) nucleus. It occurs later in specialized structures (like an ascus or basidium) right before meiosis produces haploid spores.

What is the evolutionary advantage of a prolonged dikaryotic (n + n) phase?

It allows the fungus to grow extensive mycelium and delay spore production until environmental conditions are optimal.

What are the cell walls of fungi made of?

Chitin.

Differentiate between Septate and Coenocytic hyphae.

Septate hyphae are divided into individual cells by cross walls. Coenocytic hyphae lack cross walls

forming a continuous multinucleate cell.

What are Haustoria?

Specialized fungal hyphae that penetrate host tissue and release exoenzymes for extracellular digestion.

What characterizes Phylum Zygomycota?

Coenocytic hyphae

air-dispersed spores

and representative organisms like Rhizopus (black bread mold).

What is the defining reproductive structure of Phylum Ascomycota?

The Ascus (spore sac) contained within an ascocarp. Key members include yeast

Penicillium

morels

and truffles.

What is the defining reproductive structure of Phylum Basidiomycota?

The Basidium contained within a basidiocarp. Key members include mushrooms

puffballs

toadstools

and bracket fungi.

Why are Deuteromycota called "Imperfect Fungi"?

They lack a recorded sexual reproduction stage

reproducing instead via asexual conidiospores (e.g.

ringworm

predatory fungi).

What is Mycorrhizae?

A mutualistic symbiosis between plant roots and fungal hyphae. The plant provides photosynthetic sugars

What is a Lichen

and what are its three morphological types?

A mutualistic symbiosis between a fungus and an algae or cyanobacteria. Types: Crustose (crust-like)

Foliose (leaf-like)

Fruticose (shrub-like).

Define Alternation of Generations.

A life cycle alternating between a multicellular haploid (n) gametophyte phase and a multicellular diploid (2n) sporophyte phase.

What is the Gametophyte generation?

The haploid (n) phase that originates from a spore and produces gametes (sperm and eggs) via mitosis.

What is the Sporophyte generation?

The diploid (2n) phase that develops from a zygote and produces haploid spores via meiosis inside sporangia.

What is the evolutionary trend in plant dominance?

Bryophytes are gametophyte-dominant

Define Homospory vs. Heterospory.

Homospory produces one spore type that forms a bisexual gametophyte. Heterospory produces microspores (male) and megaspores (female).

Differentiate between Isomorphic and Heteromorphic generations.

Isomorphic means gametophyte and sporophyte look identical. Heteromorphic means gametophyte and sporophyte look structurally distinct.

How does plant fertilization differ from fungal fertilization regarding the n + n stage?

Plants have a brief

transient n + n stage where karyogamy occurs almost immediately after plasmogamy

forming a 2n zygote without extensive n + n mitotic divisions.

What evolutionary challenges did plants face when colonizing land?

Desiccation

water and nutrient transport

structural support against gravity

gas exchange

and delivering sperm without water.

What are Bryophytes

and what phyla belong to this group?

Nonvascular

gametophyte-dominant land plants restricted to moist environments. Includes Phylum Bryophyta (mosses)

Hepatophyta (liverworts)

and Anthocerophyta (hornworts).

What are the key features of Phylum Pterophyta (Ferns)?

Seedless vascular plants with true roots and fronds (megaphylls). Sporophyte is dominant

What distinguishes Gymnosperms from Angiosperms?

Gymnosperms have naked seeds exposed on modified leaves/cones

whereas Angiosperms enclose their seeds within a fruit derived from an ovary.

What is the Micropyle?

A narrow opening on the ovule through which pollen grains or pollen tubes enter to reach the female gametophyte for fertilization.

What are the parts of a flower pistil/carpel (female structure)?

Stigma (pollen landing pad)

Style (connecting tube)

Ovary (houses ovules)

and Ovule (contains embryo sac).

What are the parts of a flower stamen (male structure)?

Anther (microsporangia site for pollen creation) and Filament (supporting stalk).

What is Double Fertilization in Angiosperms?

One sperm fertilizes the egg cell to produce a diploid (2n) zygote. The second sperm fuses with the binucleate central cell to form a triploid (3n) endosperm.

What is the main structural difference between Monocots and Dicots?

Monocots have 1 cotyledon in their seed

Why is seed dispersal critical for Perennial plants compared to Annuals?

Annual parents die within a year

leaving resources open. Perennial parents live multiple years

making wide seed dispersal essential to prevent competition between parent and offspring