Fungi and Plant Biology: Structure, Reproduction, and Ecosystem Roles

Role of fungi in environment

Decomposers, recyclers, symbionts, and pathogens that help ecosystems stay balanced.

New roles being discovered

Fungal networks ('Wood Wide Web') that allow plant communication and nutrient sharing.

Basic structure of fungi

Made of hyphae (filaments) that form a mycelium (body).

Fungal cell wall

Made of chitin, not cellulose.

Domain of fungi

Eukarya.

Supergroup of fungi

Opisthokonta.

Closest relatives to fungi

Animals.

Body forms of fungi

Mostly multicellular (molds, mushrooms), some unicellular (yeasts).

Movement to land (fungi story)

Evolved from aquatic protists; adapted to land as decomposers and plant partners.

How fungi eat

Secrete enzymes, digest food externally, absorb nutrients.

Term for how fungi eat

Saprotrophic.

Fungal structures for feeding

Hyphae and mycelium.

Environmental connection

Their feeding recycles nutrients into ecosystems.

Fungi reproduction types

Sexual and asexual.

Asexual reproduction in fungi

Spores made by mitosis.

Sexual reproduction in fungi

Involves plasmogamy ‚Üí heterokaryotic stage ‚Üí karyogamy ‚Üí diploid stage.

Heterokaryotic stage

Fungal cells contain two different nuclei that haven’t fused yet.

Fungal life cycle ploidy

Mostly haploid, short diploid stage.

Zygomycota

Bread molds; form zygospores.

Ascomycota

Sac fungi (yeasts, truffles); form ascospores in asci.

Basidiomycota

Club fungi (mushrooms); form basidiospores on basidia.

Lichens

Symbiosis between fungi and algae/cyanobacteria.

Common ancestor of plants

Green algae (charophytes).

Adaptations for land life

Cuticle, stomata, vascular tissue, seeds/spores.

Seedless vascular plants

Ferns; vascular tissue, spores, need moisture.

Seed plants

Gymnosperms and angiosperms; pollen and seeds, no water needed for fertilization.

Evolutionary steps in plants

Vascular tissue ‚Üí seeds ‚Üí flowers/fruits.

Cuticle function

Prevents water loss.

Stomata function

Gas exchange.

Angiosperms

Flowering plants; have fruits; attract pollinators.

Monocot vs Eudicot (vascular bundles)

Monocot: scattered; Eudicot: ring.

Xylem

Moves water and minerals upward from roots.

Roots function

Anchor plant, absorb water/nutrients, store food.

Root types

Taproot (deep main root) and fibrous (shallow spreading roots).

Spore

Single reproductive cell that grows without fertilization.

Seed advantages

Protection, dormancy, dispersal, food for embryo.

Threats to plant diversity

Deforestation, habitat loss, climate change, invasive species.

What are adaptations?

Inherited traits that improve an organism’s ability to survive and reproduce in its environment.

Define mutation.

A change in DNA that creates new alleles.

Define stabilizing selection.

Favors intermediate phenotypes and reduces variation.

Define frequency-dependent selection.

Fitness of a phenotype depends on how common it is in the population.

What is the biological species concept?

Species are groups of interbreeding populations reproductively isolated from others.

What are outcomes for hybrid zones?

Reinforcement, fusion, or stability of hybrids.

Define prezygotic barriers.

Prevent mating or fertilization between species.

Define allopatric speciation.

Speciation due to geographic isolation.

Understand how to read a phylogenetic tree.

Each branch point represents a common ancestor; closer branches mean closer relation.

What do phylogenetic trees show?

Patterns of descent, not necessarily physical similarity.

How do systematists infer phylogeny?

By comparing morphology, genetics, and molecular data.

What are character tables?

Charts showing presence or absence of traits used to build trees.

How are genes used to determine phylogeny?

DNA comparisons reveal evolutionary relationships.

What are the 3 domains of life?

Bacteria, Archaea, and Eukarya.

Define clade.

A group including an ancestor and all its descendants.

Define outgroup.

A species outside the group being studied, used for comparison.

Define ingroup.

The group of species being analyzed in a phylogenetic study.

Fungi-plant relationship

Mycorrhizae; fungi help roots absorb nutrients and water.

Parasitic fungi

Harm hosts (ex: rusts, smuts).

Fungal communication

Mycelium may send signals or nutrients between plants.

Challenges of life on land

Drying out, gravity, reproduction, nutrient transport.

Major plant groups

Seedless nonvascular, seedless vascular, seed plants.

Seedless nonvascular plants

Mosses; small, need water for reproduction.

Alternation of generations

Life cycle alternates between haploid gametophyte and diploid sporophyte.

Apical meristem

Growth region at root and shoot tips.

Gymnosperms

Cone-bearing plants (pines); naked seeds; wind pollinated.

Key adaptations in seed plants

Seeds, pollen, reduced gametophytes.

Monocot vs Eudicot (cotyledons)

Monocot: 1 cotyledon; Eudicot: 2 cotyledons.

Monocot vs Eudicot (leaf veins)

Monocot: parallel; Eudicot: branched.

Monocot vs Eudicot (roots)

Monocot: fibrous; Eudicot: taproot.

Monocot vs Eudicot (flower parts)

Monocot: multiples of 3; Eudicot: multiples of 4 or 5.

Flower parts

Sepals, petals, stamens (male), carpels/pistils (female).

Pollination types

Wind, water, animal.

Bee vision

Sees ultraviolet patterns that guide them to nectar.

Adaptations for pollination

Bright colors, nectar guides, scents.

Pollinator loss

Threatens food webs and biodiversity.

Vascular tissue significance

Allows plants to grow tall and transport materials.

Phloem

Moves sugars from leaves to other parts of plant.

What moves in xylem

Water and minerals (roots ‚Üí leaves).

What moves in phloem

Sugars (leaves ‚Üí rest of plant).

Stems function

Support plant, transport nutrients, raise leaves.

Leaves function

Photosynthesis and gas exchange.

Seed

Embryo + food supply + protective coat.

Seed vs spore difference

Seeds are multicellular with stored food; spores are single cells.

Seed adaptations

Wings, burrs, fruits, water dispersal.

Products from seed plants

Food, oils, wood, medicine, fibers.

Why plants need defense

Against herbivores, pathogens, and competition.

Physical defenses

Thorns, bark, waxy cuticles.

Chemical defenses

Toxins, bitter compounds, secondary metabolites.

Mutualistic defense

Ants protect acacia trees in return for food/shelter.

What does the term 'descent with modification' mean?

It means that species change over time, giving rise to new species while sharing a common ancestor.

What is meant by unity and diversity of life?

Unity refers to shared traits among all organisms due to common ancestry; diversity arises from adaptations to different environments.

Who is Darwin and what was his contribution to evolution?

Charles Darwin proposed the theory of natural selection as the mechanism for evolution.

What is evolution?

Change in the genetic composition of a population over generations.

What is the Linnaean classification system?

A hierarchical system of naming and classifying organisms based on shared characteristics.

How are fossils used as evidence for evolution?

Fossils show transitional forms and help trace the evolution of species through strata layers.

How do layers of strata differ?

Older layers are deeper and contain older fossils, while upper layers are more recent.

What information can fossils in different layers tell us?

They show how species changed and when certain organisms appeared or disappeared.

Describe natural selection and define fitness.

Natural selection is when individuals with advantageous traits reproduce more; fitness is the ability to survive and reproduce.

What is artificial selection?

Selective breeding by humans to promote desired traits in organisms.

Describe 4 types of evidence for evolution.

Fossil record, biogeography, comparative anatomy, molecular biology.

How has biogeography helped understand evolution?

It shows how species distribution is influenced by continental drift and isolation.

What mechanisms cause evolution in populations?

Natural selection, genetic drift, gene flow, mutation, and nonrandom mating.