Fungi and Their Reproduction

Fungi

• Fungi absorb nutrients after externally digesting their food.
• They are heterotrophic eukaryotes.
• Fungi are found everywhere.
• Fungi consist of thread-like hyphae that branch into a feeding structure called a mycelium.
• Hyphae are surrounded by a cell wall made of chitin.
• Fungi reproduce both asexually and sexually, producing spores.

Types of Fungi Reproduction

• Asexual Reproduction:
  • Molds reproduce by producing spores, often at the tips of specialized hyphae.
  • Yeasts reproduce by cell division or budding.

Five Groups of Fungi and Their Characteristics

• Basidiomycetes (club fungi): Have club-shaped spore-producing basidium; examples include mushrooms, puffballs, shelf fungi.
• Chytrids (water molds): Unique in having flagellated spores, they are decomposers and parasites.
• Zygomycetes: Form haploid spores in resistant zygosporangia; examples include fast-growing molds.
• Glomeromycetes: Soil fungi; form mycorrhizae, which are beneficial associations between fungi and plants.
• Ascomycetes (sac fungi): Have sac-like asci that produce spores; some are plant pathogens; part of symbiotic lichens.

Lichens

• Lichens consist of a mutualistic relationship between fungi and photosynthetic organisms (algae or cyanobacteria).
• The photosynthetic organisms live within a mass of fungal hyphae.

Parasitic Fungi

• Examples include Dutch elm disease, corn smut, and various skin infections (like ringworm and vaginal yeast infections).

Beneficial Fungi

• Mycorrhizae: Fungi provide essential nutrients to plants.
• Decomposers: Fungi are essential decomposers in ecosystems, consuming almost any carbon-containing substance.
• Practical uses: Fungi provide antibiotics, food, and are useful in research.

Mycorrhizae

• Fungi supply essential nutrients to plants.
• Mycorrhizae improve plant health by increasing drought and disease resistance, and by enhancing soil structure.

Plantae

Four Key Plant Adaptations to Land Life

• Dependent embryos: All plants
• Lignified vascular tissues: All vascular plants
• Seeds: Gymnosperms and angiosperms
• Flowers: Angiosperms

General Plant Features and Structure

• Reproductive structures (flowers): Contain spores and gametes
• Leaves: Carry out photosynthesis
• Cuticle: Reduces water loss; stomata: Allow gas exchange
• Stems: Support the plant and may perform photosynthesis

Plant Life Cycles (Alternation of Generations)

• Haploid Gametophyte: Produces eggs and sperm by mitosis.
• Fertilization: Results in a diploid zygote.
• Diploid Sporophyte: Develops from the zygote; produces haploid spores by meiosis.
• Spores: Grow into gametophytes.

Pine Tree Fertilization

• Reproductive stages are on sporophytes in cones.
• Ovulate cones bear ovules.
• Pollen cones produce haploid spores that develop into pollen grains.
• Pollination occurs.
• Meiosis occurs in the ovule.

Four Categories of Plants and Their Differences

• Bryophytes: Non-vascular plants
• Pteridophytes: Seedless vascular plants
• Gymnosperms: Seed-bearing, non-flowering plants
• Angiosperms: Flowering plants with seeds enclosed in fruits

Reproductive Structures of Flowering Plants

• Stamen: Stalk with an anther (pollen production) and a filament.
• Carpel: Stalk with an ovary (containing ovules) and a sticky stigma (pollen trap).
• Ovary: Chamber containing ovules where eggs develop.

General Features of Flowering Plants (Angiosperms)

• Gametophytes develop in flowers.
• Seeds are produced in an ovary and packaged inside a fruit.

Beneficial Effects of Angiosperms

• Major source of food for land animals.
• Provide most of our food and other commercial products.