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 (~$1.5$ 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 ($2n$) produces spores
  • Haploid gametophyte ($n$) 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 $\text{water}$ & minerals root → leaf
  • Phloem – transports $\text{sucrose}$ & 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, $6$ legs, often wings, metamorphosis)
  • Crustaceans: cephalothorax + abdomen; carapace (e.g., shrimp, crab, lobster, barnacle, Daphnia)
  • Arachnids: $8$ 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

6. Class Aves – Birds
   • Feathers; forelimbs as wings; lightweight, keeled sternum; air-sac respiratory system; hard-shelled eggs; 4-chambered heart
7. 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