Lab Test 2 Study Notes

Domains & Microorganisms

  • Three Domains of life
    • Archaea
    • Prokaryotic & unicellular
    • Thrive in extreme/harsh environments (thermophiles, halophiles, methanogens)
    • Bacteria
    • Prokaryotic & unicellular; ubiquitous
    • Ecological functions
      • Decomposers, nutrient cycling, digestion aid, bioremediation (breakdown of harmful compounds)
    • Eukarya
    • Includes protists, plants, fungi, animals
  • Common bacterial shapes
    • Coccus (spherical)
    • Bacillus (rod-shaped)
    • Spirillum (spiral)

Protists

  • General traits
    • Eukaryotic organisms not classified as plants, fungi, or animals
    • Mostly unicellular; ancestral to all other eukaryotes
  • Nutritional modes
    • Autotrophs (photosynthetic algae; chloroplast-bearing)
    • Heterotrophs (ingest or absorb)
    • Mixotrophs (Euglena) – combine photo- & heterotrophy
  • Protozoans (animal-like protists)
    • Flagellates (e.g., Giardia) – move with flagella; many free-living, some parasitic
    • Ciliates (e.g., Paramecium) – use cilia for locomotion & feeding; mostly free-living
    • Amoebas – move/feed via pseudopodia; highly flexible body form; lack permanent locomotory organelles
  • Photosynthetic/plant-like protists (algae)
    • Green algae
    • Unicellular (Chlamydomonas), sometimes flagellated
    • Colonial forms (Volvox) – hollow spheres of flagellated cells
    • Seaweeds (multicellular algae)
    • Classified by pigment sets in chloroplasts
      • Green algae
      • Red algae (e.g., nori used in sushi)
      • Brown algae (kelps)

Fungi

  • Fundamental characteristics
    • Heterotrophic eukaryotes; more closely related to animals than plants (~1.51.5 billion-year shared ancestor)
    • Chemoheterotrophs; nutrition by absorption
    • Secrete extracellular digestive enzymes, then absorb monomers
  • Structure
    • Body composed of hyphae (thread-like, chitin-walled filaments of cytoplasm surrounded by membrane)
    • Hyphae interweave into a mycelium – primary feeding structure
    • Mushrooms = reproductive structures emerging from underground mycelia
  • Reproduction
    • Release haploid spores (sexual or asexual)
  • Examples to recognize microscopically or macroscopically
    • Peziza (cup fungus) – asci & spores visible in cross-section
    • Morel – honeycomb ascocarp
    • Coprinus (inky cap) – cap, gills, spores; hyphae in slide
    • Bracket fungi (shelf fungi on trees)
    • Lichens – symbiosis of fungus + algae/cyanobacteria; growth forms: crustose, foliose, fruticose
  • Commercial significance
    • Edible mushrooms, penicillin production, decomposition, fermentation (bread, beer, wine, cheeses)

Plants

  • Basic traits: Multicellular, eukaryotic, photoautotrophic producers
  • Major lineages
    • Nonvascular (mosses, liverworts) – lack true xylem/phloem; dominant gametophyte
    • Seedless vascular (ferns, horsetails) – have vascular tissue; reproduce by spores
    • Gymnosperms (conifers & allies) – vascular, naked seeds in cones; pollen/ovule cones
    • Angiosperms (flowering plants) – vascular, seeds within fruits; flowers attract pollinators
  • Alternation of generations
    • Diploid sporophyte (2n2n) produces spores
    • Haploid gametophyte (nn) produces gametes
    • Dominance shifts
    • Gametophyte larger in nonvascular plants
    • Sporophyte larger in vascular plants
  • Flower anatomy (angiosperm)
    • Sepals (outer whorl) – protection
    • Petals – attraction
    • Stamens (male): filament + anther (pollen)
    • Carpel/Pistil (female): ovary → style → stigma; ovules inside ovary
    • Receptacle – swollen stem tip supporting whorls
  • Vascular tissues
    • Xylem – transports water\text{water} & minerals root → leaf
    • Phloem – transports sucrose\text{sucrose} & other organics leaf → roots/other sinks

Biological Classification Review

  • Hierarchical ranks (most → least inclusive)
    • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species
    • Mnemonics: “Darling Kids Play Checkers On Funny Green Squares” / “Dumb King Phil Came Over For Good Spaghetti.”
  • Binomial nomenclature
    • Genus capitalized, species lowercase, both italicized/underlined: Homo sapiens

Kingdom Animalia – General Traits

  • Multicellular, eukaryotic, heterotrophic
  • At least one motile life-stage; most reach organ-system level organization

Invertebrate Phyla (Lab Focus)

Phylum Porifera – Sponges

  • Simplest animals; no true tissues/organs; internal spicules provide support

Phylum Cnidaria – Jellyfish, Corals, Hydra

  • Radial symmetry; no coelom
  • Cnidocytes with nematocysts on tentacles; body forms
    • Polyp (anchored; e.g., Hydra)
    • Medusa (free-floating; jellyfish)

Phylum Platyhelminthes – Flatworms

  • Bilateral symmetry; acoelomate; first with cephalization (head)
  • Classes: Planarians (free-living), Flukes (internal parasites), Tapeworms (e.g., Echinococcus, scolex + proglottids)

Phylum Nematoda – Roundworms

  • Bilateral; pseudocoelom; complete digestive tract; chitinous cuticle; ubiquitous (e.g., Ascaris, Trichinella)

Phylum Annelida – Segmented Worms

  • True coelom (eucoelomate); segmentation; classes: Earthworms (Lumbricus), Clamworms, Leeches

Phylum Arthropoda – Detailed in next section

Phylum Mollusca – Detailed later

Phylum Echinodermata – Sea stars, urchins, sand dollars

  • Radial symmetry (adults) & water vascular system; “spiny skin”

Phylum Arthropoda

  • Most diverse & abundant animal phylum; first land animals
  • Key characteristics
    • Chitinous, jointed exoskeleton; must molt for growth
    • Segmentation; body regions vary
    • Insects: head, thorax, abdomen (3 regions, 66 legs, often wings, metamorphosis)
    • Crustaceans: cephalothorax + abdomen; carapace (e.g., shrimp, crab, lobster, barnacle, Daphnia)
    • Arachnids: 88 legs; spiders, scorpions, mites, ticks
  • Ecological roles: pollination, food sources, disease vectors

Phylum Mollusca

  • Second-largest animal phylum (after arthropods); aquatic & some terrestrial
  • Body organization
    • Visceral mass (internal organs) enclosed by mantle (may secrete shell)
    • Muscular foot for movement
    • Radula (rasping tongue) in many taxa
  • Major classes
    • Bivalvia (clams, oysters, scallops) – two hinged shells
    • Gastropoda (snails, slugs, cone shells, nudibranchs) – first mollusks to colonize land
    • Cephalopoda (squid, octopus, nautilus) – tentacles with suckers; highly developed nervous system

Phylum Echinodermata

  • Marine; adult radial symmetry; water vascular system with tube feet
  • Examples: sea star (ambulacral groove, central disc), sea urchin, sand dollar

Phylum Chordata – Overview

  • Defining features present at some stage
    • Notochord (flexible rod)
    • Dorsal hollow nerve cord
    • Pharyngeal gill slits/pouches
  • Subphyla
    • Invertebrate chordates: tunicates, lancelets (filter feeders)
    • Vertebrates: have vertebral column

Vertebrate Classes

Lower (Cold-blooded) Vertebrates

  1. Class Agnatha – Jawless fish (sea lamprey, hagfish)
    • Eel-like, persistent notochord, no paired fins, circular mouth with horny teeth; some parasitic
  2. Class Chondrichthyes – Cartilaginous fish (sharks, rays)
    • Movable jaws, vertebrae, paired fins; cartilage skeleton; no swim bladder; tough skin
  3. Class Osteichthyes – Bony fish (bass, salmon, trout, tuna, tropical aquarium species)
    • Bony skeleton; operculum over gills; swim bladder for buoyancy
  4. Class Amphibia (frogs, toads, salamanders)
    • Moist skin aids respiration; many with lungs &/or gills; eggs laid in water; ectothermic; dual life style
  5. Class Reptilia (turtles, snakes, lizards, crocodilians)
    • Dry scaly skin; lungs; internal fertilization; amniotic egg (leathery/shelled); 3-chambered heart (4 in crocodiles)

Higher (Warm-blooded) Vertebrates

  1. Class Aves – Birds
    • Feathers; forelimbs as wings; lightweight, keeled sternum; air-sac respiratory system; hard-shelled eggs; 4-chambered heart
  2. Class Mammalia – Mammals
    • Hair; mammary glands; diaphragm; internal fertilization; placenta in most; large brain
    • Male: penis & typically external testes in scrotum
    • Mammalian groups
    1. Monotremes – egg-laying (platypus, echidna)
    2. Marsupials – pouched; limited to Australia/S. America plus North-American opossum
    3. Placentals (eutherians) – majority of mammals, live birth to well-developed young

Frog Anatomy (Lab Dissection Targets)

  • Organs to identify & label
    • Respiratory: Lungs
    • Circulatory: Heart
    • Digestive: Liver, Gall bladder, Stomach, Small intestine, Large intestine
    • Energy storage: Fat bodies
  • Must also recognize external & internal anatomy for class identification exercises

Quick Reference & Study Tips

  • Be prepared to recognize representatives of each invertebrate & vertebrate class (slides, preserved specimens, live demo)
  • Practice labeling flower parts and frog internal organs from diagrams/photos
  • Memorize alternation of generations life-cycle with dominance differences
  • Recall vascular tissue functions (xylem vs. phloem) and directionality
  • Use classification mnemonics and proper italics for genus/species in lab write-ups
  • Ethics & real-world relevance
    • Bioremediation by microbes; fungal antibiotics; insect pollination’s role in food security; vertebrate anatomy informing comparative physiology & medical advances