Chapter 18 – The Fungi and Plants (Essentials of Biology, 6e)

A comprehensive set of Q&A flashcards covering fungal biology, plant evolution, plant anatomy, reproduction, ecological roles, and economic importance to aid exam preparation.

Are fungi more closely related to plants or animals in terms of nutrition and why?

Animals—both fungi and animals are chemoheterotrophs (obtain carbon and energy from organic compounds).

What filamentous structures make up the body of a typical fungus?

Hyphae (singular: hypha).

What is a mycelium?

The mass of intertwined hyphae that forms the main body of a fungus.

Why do hyphae provide a high efficiency for nutrient absorption?

Their large surface-to-volume ratio increases contact with the substrate.

What are the temporary, reproductive structures of a fungus commonly called?

Fruiting bodies (e.g., mushrooms, puffballs).

What polysaccharide is found in fungal cell walls?

Chitin.

What name is given to the cross-walls that separate most fungal cells?

Septa (singular: septum).

In fungal sexual reproduction, what term describes hyphae that contain two genetically distinct nuclei per cell?

Dikaryotic hyphae.

Define a fungal spore.

A haploid reproductive cell that can germinate into a new mycelium without fusion with another cell.

During fungal sexual reproduction, what process follows plasmogamy?

Karyogamy (fusion of nuclei to form a diploid zygote).

Approximately how many described species of fungi exist?

About 74,000.

What ecological role do most fungi play?

Saprotrophs that decompose dead organic matter and recycle nutrients.

Name two major mutualistic relationships involving fungi.

Lichens (fungus + algae/cyanobacteria) and mycorrhizae (fungus + plant roots).

How do lichens survive in harsh habitats such as bare rock?

The fungal partner provides moisture and minerals; the photosynthetic partner produces organic food.

What benefit do mycorrhizal fungi provide to plants?

Greatly increased surface area for absorption of water, phosphorus, nitrogen, and other nutrients.

Which genus of fungus was the original source of penicillin?

Penicillium.

List three common human foods or beverages produced with the help of fungi.

Bread, beer, wine (all via yeast fermentation).

What fungal disease annually destroys up to one-third of the world’s rice crop?

Rice blast disease.

Define mycosis.

Any disease caused by a fungus.

What common fungal species causes thrush and vaginal yeast infections?

Candida albicans.

Why is designing antifungal drugs challenging?

Fungi are eukaryotes and share many cellular similarities with humans, so drugs may harm human cells too.

List two key differences between fungi and plants regarding cell wall composition and nutrition.

Fungal cell walls contain chitin (plants have cellulose); fungi are chemoheterotrophic by absorption, whereas plants are photosynthetic.

From which ancestral group did land plants most likely evolve?

Freshwater green algae (specifically charophytes).

Name the five major evolutionary events in plant evolution, in order.

1) Embryo protection; 2) Vascular tissue; 3) Megaphylls; 4) Seeds; 5) Flowers.

Which generation (sporophyte or gametophyte) is dominant in bryophytes?

The gametophyte (haploid) generation.

What is the dominant generation in vascular plants?

The sporophyte (diploid) generation.

Define alternation of generations.

A life cycle in which plants alternate between a multicellular haploid gametophyte and a multicellular diploid sporophyte.

What distinguishes nonvascular plants from vascular plants?

Nonvascular plants lack specialized conducting tissue (xylem and phloem) and rely on diffusion/osmosis; vascular plants possess xylem and phloem.

Give two examples of bryophytes.

Mosses and liverworts.

What two tissues make up the vascular system of plants?

Xylem (water/mineral conduction) and phloem (carbohydrate conduction).

What structures in plants conduct water upward from roots?

Xylem vessels/tracheids.

Which seedless vascular plants are the most abundant today?

Ferns.

What leaf structures on fern sporophytes produce spores?

Sori (clusters of sporangia) located on the underside of fronds.

In seed plants, what is a pollen grain?

The male gametophyte that carries sperm cells.

What three components make up a typical seed?

1) Sporophyte embryo, 2) Stored food (endosperm or cotyledon), 3) Protective seed coat.

Why are seeds considered a major adaptation to life on land?

They protect the embryo, enable dormancy and dispersal, and supply nourishment during early growth.

Differentiate between gymnosperms and angiosperms regarding ovule enclosure.

Gymnosperm ovules are exposed on cone scales (“naked seeds”); angiosperm ovules are enclosed within the carpel and become part of a fruit.

Name two living gymnosperm groups.

Conifers (e.g., pines) and cycads.

What structure in conifers houses the female gametophyte?

Seed cone (ovulate cone) containing ovules.

Angiosperms make up roughly what percentage of modern plant species?

About 90%.

What floral whorl is collectively called the calyx?

The sepals.

Which part of a flower produces pollen?

The anther of the stamen.

Name the three main parts of a carpel.

Ovary, style, stigma.

What is double fertilization in angiosperms?

One sperm fertilizes the egg to form a zygote, while the other fuses with two nuclei to form triploid endosperm.

After fertilization, what does the ovule become?

A seed.

After fertilization, what does the ovary usually develop into?

A fruit.

Give one example of how flowers are adapted to attract specific pollinators.

Bee-pollinated flowers often have ultraviolet nectar guides visible to bees but not to humans.

List four methods by which seeds can be dispersed.

Wind, water, animals, and mechanical bursting/gravity.

What term describes the mutually beneficial evolution of flowering plants and their pollinating insects?

Co-evolution.

Mention two major economic benefits provided by plants.

Food production and pharmaceuticals (e.g., many medicines originate from plant compounds).

What role do forests play in global ecological cycles?

They are critical in the carbon and water cycles, sequestering CO₂ and influencing precipitation and runoff.

How can plants be used in environmental cleanup?

Phytoremediation—using plants to absorb or stabilize toxic substances in soil and water.