Biological Principles II: Study Guide for Fungi, Animal Diversity, Invertebrates, and Vertebrates

Chapter 31: Fungi

Introduction to the Fungi

Fungi are a diverse kingdom of eukaryotic organisms distinct from plants, animals, and protists. They play crucial roles in ecosystems as decomposers, symbionts, and pathogens.

• Distinguishing Characteristics: Fungi are heterotrophic, absorb nutrients, have cell walls made of chitin, and reproduce via spores.

• Nutrient Acquisition: Fungi secrete enzymes to break down complex molecules and absorb the resulting nutrients.

• Body Plan:

  • Mycelium: Network of hyphae that increases surface area for absorption.

  • Hyphae: Filamentous structures; can be septate (with cross-walls) or coenocytic (without cross-walls).

  • Fruiting Body: Reproductive structure (e.g., mushroom) that produces spores.

• Mycorrhizal Fungi:

  • Ectomycorrhizal: Form sheaths around roots, do not penetrate cells.

  • Arbuscular (Endomycorrhizal): Penetrate root cell walls, forming arbuscules.

• Reproduction:

  • Plasmogamy: Fusion of cytoplasm from two parent mycelia.

  • Karyogamy: Fusion of nuclei, forming diploid cells.

  • Heterokaryotic Stage: Cells contain two or more genetically distinct nuclei.

• Fungal Life Cycle: Includes both asexual and sexual reproduction. Key stages:

  • Haploid: Spores, mycelium

  • Heterokaryotic: After plasmogamy, before karyogamy

  • Diploid: After karyogamy, before meiosis

  • Meiosis: Produces haploid spores

  • Germination: Spores develop into new mycelium

Diversity of Fungi

Fungi and animals are sister kingdoms, sharing a common ancestor. Multicellularity evolved independently in both.

• Glomeromycetes: Ecologically important for forming arbuscular mycorrhizae with plants.

• Major Fungal Divisions:

  • Chytridiomycota: Aquatic, flagellated spores.

  • Glomeromycota: Arbuscular mycorrhizal fungi.

  • Zygomycota: Form zygosporangia; life cycle includes zygospore.

  • Ascomycota: Produce spores in asci; life cycle includes ascocarp.

  • Basidiomycota: Produce spores on basidia; life cycle includes basidiocarp (mushroom).

Ecological Impacts of Fungi

Fungi are essential in nutrient cycling, symbiosis, and disease.

• Roles:

  • Decomposers: Break down dead organic matter.

  • Parasites: Cause diseases in plants and animals.

  • Mutualists: Form beneficial relationships (e.g., mycorrhizae, lichens).

• Mycosis: Fungal infection in animals or humans (e.g., athlete's foot, ringworm).

• Lichen Structure: Symbiotic association between fungus and photosynthetic partner (alga or cyanobacterium). Fungus provides structure and protection.

Chapter 32: An Overview of Animal Diversity

What Is an Animal?

Animals are multicellular, heterotrophic eukaryotes with specialized tissues and complex development.

• Defining Characteristics: Multicellularity, heterotrophy, lack of cell walls, motility, sexual reproduction.

• Feeding Habits: Herbivores, carnivores, omnivores, filter feeders, parasites.

• Major Tissue Types: Epithelial, connective, muscle, nervous.

• Development: Zygote undergoes cleavage, forms blastula, then gastrulation creates germ layers.

  • Cleavage: Rapid cell division.

  • Gastrulation: Formation of archenteron (primitive gut), blastocoel (cavity), blastopore (opening).

• Metamorphosis: Transformation from larva to adult. Complete metamorphosis involves distinct larval and adult stages; incomplete metamorphosis has gradual changes.

• Hox Genes: Regulate body plan development; highly conserved across animals.

The Origins of Animal Diversity

Animal diversity is classified by grades and clades, based on symmetry, tissue layers, body cavities, and development.

• Grades vs. Clades: Grades are groups based on shared features; clades are evolutionary lineages.

• Symmetry:

  • Radial: Body parts arranged around a central axis (e.g., jellyfish).

  • Bilateral: Two-sided symmetry (e.g., humans).

• Embryonic Tissue Layers:

  • Diploblastic: Two layers (ectoderm, endoderm).

  • Triploblastic: Three layers (ectoderm, mesoderm, endoderm).

• Body Cavity Types:

  • Acoelomate: No body cavity.

  • Pseudocoelomate: Body cavity not fully lined by mesoderm.

  • Coelomate: True body cavity lined by mesoderm.

• Cleavage Patterns:

  • Spiral: Cells divide at angles; typical of protostomes.

  • Radial: Cells divide parallel/perpendicular; typical of deuterostomes.

  • Determinant: Fate of cells fixed early.

  • Indeterminate: Cells retain potential to develop into complete organism.

• Protostome vs. Deuterostome:

  • Protostome: Blastopore becomes mouth.

  • Deuterostome: Blastopore becomes anus.

Animal Phylogeny

• Five Major Features: (1) All animals share a common ancestor; (2) Sponges are basal; (3) Eumetazoa have true tissues; (4) Most animals are bilaterians; (5) Bilateria split into three major clades: Deuterostomia, Ecdysozoa, Lophotrochozoa.

• Deuterostomia:,which are typically characterized by their blastopore becoming their anus during embryonic development.

• Ecdysozoans: Molt exoskeleton (e.g., arthropods, nematodes).

• Lophotrochozoans: Have lophophore or trochophore larva (e.g., mollusks, annelids).

Chapter 33: An Introduction to Invertebrates

Radiates

Radiate animals include basal groups with simple body plans and radial symmetry.

• Sponges (Porifera): Basal animals, lack true tissues, filter feeders.

• Ctenophora: Comb jellies; have cilia for movement.

• Cnidaria: Jellyfish, corals, sea anemones; have cnidocytes (stinging cells), radial symmetry.

• Cnidarian Body Plans:

  • Polyp: Sessile, cylindrical.

  • Medusa: Free-swimming, bell-shaped.

Lophotrochozoa

Lophotrochozoans are a diverse clade of invertebrates with varied body plans and life cycles.

• Platyhelminthes: Flatworms; lack body cavity, simple organs.

• Annelida: Segmented worms; have true coelom, closed circulatory system.

• Mollusca: Soft-bodied, often with shell; body plan includes mantle, foot, visceral mass.

  • Bivalvia: Two shells (clams, oysters).

  • Gastropoda: Single shell or none (snails, slugs).

  • Polyplacophora: Multiple plates (chitons).

  • Cephalopoda: Tentacles, advanced nervous system (octopus, squid).

Ecdysozoa

Ecdysozoans are characterized by molting their exoskeleton.

• Nematoda: Roundworms; unsegmented, pseudocoelomate.

• Arthropoda: Segmented bodies, jointed appendages, exoskeleton of chitin.

  • Chelicerates: Spiders, scorpions.

  • Crustaceans: Crabs, lobsters.

  • Insects: Largest group; wings, metamorphosis.

• Exoskeleton: Provides protection and support; limits growth and requires molting.

Deuterostomia

Deuterostomes include echinoderms and chordates, sharing developmental similarities.

• Echinoderms: Starfish, sea urchins; radial symmetry as adults, water vascular system.

• Chordates: See Chapter 34.

Chapter 34: The Origin and Evolution of Vertebrates

Phylum Chordata

Chordates are defined by four derived traits and have evolved diverse forms, including vertebrates.

• Four Derived Traits:

  1. Notochord: Flexible rod for support.

  2. Dorsal, hollow nerve cord: Develops into central nervous system.

  3. Pharyngeal slits: Openings for filter feeding or gas exchange.

  4. Post-anal tail: Muscular tail extending beyond anus.

• Genetic Duplication: Duplications of Hox genes contributed to complexity in chordate evolution.

• Hagfish: Ancestral features: jawless, cartilaginous skeleton; derived features: slime production.

• Gnathostomes: Jawed vertebrates; include fish, amphibians, reptiles, birds, mammals.

• Tetrapods: Four-limbed vertebrates; include amphibians, reptiles, birds, mammals.

• Amniotes: Vertebrates with amniotic egg; include reptiles, birds, mammals.

• Amphibians: Moist skin, life cycle includes aquatic larva and terrestrial adult.

• Amniotic Egg: Contains membranes for protection and nourishment; key adaptation for terrestrial life.

• Reptile Clade: Includes birds due to shared ancestry.

• Reptile Adaptations: Scales, shelled eggs, ectothermy.

• Bird Adaptations: Feathers, hollow bones, high metabolism, flight adaptations.

• Mammal Traits: Hair, mammary glands, endothermy, differentiated teeth.

• Mammal Groups:

  • Monotremes: Egg-laying (platypus).

  • Marsupials: Pouch development (kangaroo).

  • Eutherians: Placental mammals (humans).

Comparison Table: Animal Body Cavity Types

Type	Definition	Example
Acoelomate	No body cavity	Flatworm
Pseudocoelomate	Body cavity not fully lined by mesoderm	Roundworm
Coelomate	True body cavity lined by mesoderm	Earthworm

Comparison Table: Major Animal Clades

Clade	Key Features	Examples
Ecdysozoa	Molting exoskeleton	Arthropods, Nematodes
Lophotrochozoa	Lophophore/trochophore larva	Mollusks, Annelids
Deuterostomia	Blastopore becomes anus	Echinoderms, Chordates

Comparison Table: Mammal Groups

Group	Reproduction	Example
Monotreme	Egg-laying	Platypus
Marsupial	Pouch development	Kangaroo
Eutherian	Placental	Human

Additional info: This study guide expands on the outline by providing definitions, examples, and comparisons to aid understanding. For diagrams and flashcard examples, refer to course materials.