Biol 1407 Exam 3 ch 27-38

Producers – General Concepts

• Definition: Organisms that manufacture their own organic food from inorganic sources in the non-living environment (autotrophs).

  • Nearly all utilize photosynthesis; a few use chemosynthesis.

• Two Cell Types

  • Prokaryotic – e.g., cyanobacteria.

  • Eukaryotic – e.g., algae, plants.

• Ecological role: Form the base of food webs; support organisms from zooplankton to large fish (e.g., tuna, sharks).

Energy & Carbon ‑ Nutritional Modes in Prokaryotes

• \textbf{Photoautotroph} – Light energy, \text{CO}_2 carbon source.

  • Cyanobacteria, plants, algae.

• \textbf{Chemoautotroph} – Inorganic chemicals (e.g., \text{NH}3, \text{H}2S), \text{CO}_2 carbon source.

  • Unique to some bacteria & archaea (e.g., Sulfolobus).

• \textbf{Photoheterotroph} – Light energy, organic carbon.

  • Certain aquatic & halophilic prokaryotes (Rhodobacter, Chloroflexus).

• \textbf{Chemoheterotroph} – Organic energy & carbon.

  • Most prokaryotes, fungi, animals, many protists.

Cyanobacteria (Blue-Green Algae)

• Gram-negative photoautotrophs; first major oxygen producers (>3.5 billion-year-old fossils – oldest known).

• Possess internal thylakoid-like membranes; perform \text{N}_2-fixation.

• Major component of marine & freshwater phytoplankton; base of aquatic food webs.

Protists – Micro-Eukaryotic Producers

• Eukaryotes that are not plants, animals, or fungi; most unicellular.

• Algae: Aquatic, photosynthetic protists (uni- & multicellular); together with cyanobacteria form primary production in water.

• Current hypothesis groups all eukaryotes into four supergroups.

Major Photosynthetic Protist Groups

• Diatoms – Unicellular algae, glass-like silica wall; highly diverse phytoplankton.

• Dinoflagellates – Two flagella, cellulose plates; phototrophs, mixotrophs, heterotrophs; blooms cause toxic “red tides.”

• Red Algae – Accessory pigment phycoerythrin masks chlorophyll; mostly multicellular seaweeds; abundant in tropical coasts.

• Green Algae – Grass-green chloroplasts; closest relatives of land plants.

• Euglenozoa – Spiral/crystalline rod in flagella; mixotrophs, parasites.

  • Trypanosoma spp. cause Chagas disease & African sleeping sickness.

Algal Symbioses

• Lichens: Mutualism between algae (photosynthesis) & fungi (structure); pioneers on bare rock/soil.

• Coral Reefs: Algae live in coral polyps, supply food & color; essential for reef building.

Ecological Concerns

• Declining protist biomass as sea-surface temperature rises – warm water blocks nutrient upwelling.

• Human fertilizer runoff + warming ➔ algal blooms ➔ decomposition creates oxygen-poor dead zones.

Early Land Plants

Shared Derived Traits (all land plants)

• Alternation of generations.

• Multicellular, dependent embryos.

• Apical meristems (localized growth regions).

Non-Vascular Plants (Bryophytes)

• Mosses, liverworts, hornworts; gametophyte dominant.

• Lack true roots (have rhizoids), leaves (have thalli), vascular tissue.

• Need water for flagellated sperm.

• Sphagnum (peat moss): Forms peat – partially decayed organic matter; fuel source; acidic, low-O₂ peatlands preserve organisms.

Seedless Vascular Plants

• Ferns, horsetails; first tall plants (Devonian–Carboniferous).

• Vascular tissue allows height:

  • Xylem – Water & mineral transport; lignified tracheids for support.

  • Phloem – Distributes sugars & organics.

• Still require water for fertilization; formed vast coal forests (Carboniferous).

Seed Plants

• Origin \approx 360 MYA; dominate terrestrial ecosystems.

• Key innovations: reduced gametophytes, heterospory, ovules, pollen, seeds.

• Advantages of seeds vs spores: dormancy until favorable, food supply, long-distance dispersal.

Gymnosperms – “Naked Seeds” (on cones)

• 4 phyla: Ginkgophyta, Cycadophyta, Gnetophyta, Coniferophyta (largest; evergreen, woody cones).

• Medicinal / toxic notes: Ginkgo biloba extracts (memory claims, side effects); Ephedra (ephedrine – stimulant, banned in US).

Angiosperms – Flowering Plants

• Reproductive structures: flowers & fruits; phylum Anthophyta.

• Flower parts: sepals, petals, stamens (anther + filament), carpels/pistils (stigma, style, ovary).

• Double fertilization ➔ seed inside ripened ovary (fruit).

• Fruits aid seed dispersal; ethylene (\text{C}2\text{H}4) gas promotes ripening (one bad apple…).

• Provide \ge 80\% of human calories – six staples (wheat, rice, maize, potato, cassava, sweet potato).

• Plant-derived medicines: Atropine, Digitalin, Menthol, Quinine, Taxol, Tubocurarine, Vinblastine.

• Threats: Habitat loss may cause 50\% species extinction within centuries; loss cascades to dependent animals; undiscovered drugs at risk.

Plant Structure, Growth & Adaptations

Roots

• Functions: anchor, absorb water/minerals, store carbs.

• Root hairs ↑ surface area; mycorrhizal associations.

• Modifications:

  • Storage roots (sweet potato), prop roots (corn), pneumatophores (mangroves for \text{O}_2), buttress roots (tropics), strangling aerial roots (strangler figs).

Stems

• Nodes (leaf attachment) & internodes.

• Buds: Apical (primary elongation) vs Axillary (lateral branches, flowers, thorns).

• Modified stems: stolons/runners (asexual spread), rhizomes, tubers (potatoes – eyes = axillary buds), corms, thorns (defense).

Leaves

• Photosynthetic organs; some modifications:

  • Storage “bulbs” (onion), tendrils (grasp), spines (cacti defense).

Meristems

• Apical meristems: Primary (length) growth.

• Lateral meristems: Secondary (thickness) growth.

  • Vascular cambium – Adds secondary xylem (wood) & phloem.

  • Cork cambium – Replaces epidermis with protective periderm.

• Dendrochronology: Tree-ring analysis for past climate.

Soil & Plant Nutrition

• Soil texture: sand > silt > clay.

• Topsoil: mineral particles + living organisms + humus (decaying organic matter).

• Loams: \approx equal sand, silt, clay – most fertile.

• Agriculture depletes minerals, water, increases erosion (e.g., Dust Bowl); \sim30\% farmland degraded.

• Organic fertilizers (manure, compost) restore nutrients.

• Soil organisms decompose organic matter, mix soil.

• Crop rotation: Alternate legumes with non-legumes to exploit symbiotic \text{N}_2-fixation.

• Special plants: Epiphytes (grow on other plants), parasitic plants (tap host sugars/minerals), carnivorous plants (trap insects to obtain nitrogen).

Animals – Kingdom of Consumers

• Multicellular heterotrophs; ingest food.

• Unique cell types: nerve & muscle; cells form tissues (functional units).

• Many have body cavities (coeloms) – fluid cushions organs, allows independent movement.

Symmetry & Body Plans

• Radial (e.g., cnidarians) vs Bilateral (dorsal/ventral, anterior/posterior).

Invertebrates (≈95\% of animals)

1. Porifera (Sponges) – No true tissues, filter feeders, sequential hermaphrodites.

2. Cnidaria – Radial, gastrovascular cavity, stinging cnidocytes; polyp & medusa forms; nerve net; coral reefs build calcium exoskeletons.

3. Platyhelminthes (Flatworms) – Acoelomate; centralized nervous system.

   • Free-living planarians regenerate with memory retention.

   • Parasites: flukes (snail intermediate), tapeworms (no gut; absorb nutrients; pork, beef, flea life cycles).

4. Nematoda (Roundworms) – Pseudocoelomate; complete gut; no circulatory system; some parasites (hookworm \sim0.5 billion infections, Ascaris \sim1 billion; Trichinella from undercooked pork).

5. Mollusca – Soft body, CaCO₃ shell (most); open circulatory except cephalopods.

   • Classes:
     • Polyplacophora (chitons)
     • Gastropoda (snails, slugs) – many hermaphrodites.
     • Bivalvia (clams, oysters, mussels, scallops) – two-part shell, adductor muscles.
     • Cephalopoda (squid, octopus) – closed circulation, beak, tentacles, ink, complex brain.

   • Molluscs suffer highest recorded extinctions.

6. Annelida – Segmented worms; closed circulation; earthworms (soil aeration, hermaphrodites, can reproduce by fragmentation), leeches (blood-sucking, predators).

7. Arthropoda – Segmented body, jointed appendages, exoskeleton (chitin), open hemolymph system; >1 million species.

   • Major lineages: Chelicerates (spiders, ticks), Myriapods (centi- & millipedes), Pancrustaceans (insects, crustaceans).

   • Insects (Hexapoda): 3 body segments, 3 leg pairs, most undergo metamorphosis (larva \rightarrow pupa \rightarrow adult); internal fertilization; wings in many.

   • Crustaceans: Isopods, decapods (lobsters, crabs), copepods (zooplankton).

   • Arachnids: 4 walking leg pairs, pedipalps, chelicerae; many spin silk.

Chordates & Vertebrates

Four Key Chordate Traits

1. Notochord (flexible rod). 2. Dorsal hollow nerve cord. 3. Pharyngeal slits/clefts. 4. Post-anal tail.

Fish

• Chondrichthyans – Cartilaginous skeleton (sharks, rays).

  • Must swim to avoid sinking & ventilate gills.

  • Acute senses; electrical field detection.

  • Reproduction:
    • \text{Oviparous} – eggs laid.
    • \text{Ovoviviparous} – eggs hatch internally.
    • \text{Viviparous} – placenta-like nourishment.

• Osteichthyes – Bony fish & lobe-fins.

  • Swim bladder for buoyancy; bony scales; mostly oviparous.

Tetrapods

• Four limbs with digits, neck, fused pelvic girdle, loss of gills (most), ears.

Amphibians (≈6,150 spp.)

• Frogs, salamanders, caecilians.

• Aquatic larva with gills → metamorphosis → terrestrial adult with lungs.

• External fertilization; eggs need moisture.

Amniotes

• Amniotic egg – Protective shell + extra-embryonic membranes (amnion, chorion, yolk sac, allantois); enables full terrestrial life; rib ventilation, waterproof skin.

Reptiles

• Scales (keratin), internal fertilization, shelled eggs, ectothermic (except birds).

• Groups: Turtles (fused shell), Lepidosaurs (lizards, snakes – venom, heat sensors), Crocodilians, Birds.

• Birds: Feathers (keratin), hollow bones, one ovary, no teeth, endothermic; hard-shelled eggs; efficient flight metabolism.

Mammals

• Derived traits: mammary glands (milk), hair, fat insulation, kidneys, endothermy, large brain-to-body ratio, differentiated teeth, parental care.

• Lineages:

  • Monotremes – Egg-laying (platypus, echidnas); lack nipples (milk on skin).

  • Marsupials – Pouched mammals (kangaroos, opossums, koalas); short gestation, embryonic young crawl to marsupium.

  • Eutherians (Placental mammals) – Long gestation, complex placenta (not detailed in transcript but implied).

• Primates: Hands/feet with grasping, flat nails, large brain, forward eyes, fully opposable thumb (monkeys & apes); humans included.

Heterotroph Categories (Feeding Modes)

• Carnivores, Herbivores, Omnivores, Detritivores (e.g., earthworms), Scavengers, Filter feeders (sponges).

Key Terminology & Concepts Summary

• Meristem: Active plant cell division; apical (primary) vs lateral (secondary).

• Alternation of Generations: Plant life cycle alternates haploid gametophyte & diploid sporophyte.

• Homospory vs Heterospory: One vs two spore types; seed plants are heterosporous.

• Body Cavity (Coelom): Enables organ independence & hydrostatic function.

• Percentage figures:

  • Invertebrates constitute 95\% of animal species.

  • Six angiosperm crops supply 80\% of human calories.

• Crop rotation, organic fertilizer, nitrogen fixation – sustainability principles.

• Ethylene gas – plant hormone; accelerates fruit ripening (“one bad apple”).

These bullet-point notes compile and connect all major and minor ideas, definitions, examples, numerical facts, and biological relationships mentioned throughout the transcript, providing a self-contained study resource.