Topic 9: Origin of Life
Learning Outcomes:
1. Identify biological events that define the geologic record:
- 4.6 bya: Formation of Earth.
- 3.9 bya: First life (replicating molecules).
- 3.5 bya: First prokaryotes.
- 2.7 bya: Oxygen in the atmosphere (Great Oxidation Event).
- 1.8 bya: First eukaryotes.
- 1.3 bya: First multicellular eukaryotes.
- 500 mya: Colonization of land by fungi, plants, and animals.
- 535–525 mya: Cambrian explosion (diversification of animal forms).
2. Describe the uses and limitations of the fossil record:
- Uses: Calibrate phylogenies, record extinct species, and link evolutionary events with geological changes.
- Limitations: Biased towards hard-bodied, abundant, and widespread organisms; incomplete due to episodic sediment deposition.
3. Explain the impact of Permian and Cretaceous extinctions:
- Permian (252 mya): Most severe extinction; ~60% of families, 81% of marine species, and 70% of terrestrial vertebrates extinct. Likely caused by volcanic activity leading to global warming and ocean acidification.
- Cretaceous (66 mya): ~50% of marine species and non-avian dinosaurs extinct. Likely caused by an asteroid impact.
4. Describe events leading to adaptive radiation:
- Adaptive radiation occurs after mass extinctions or colonization of new habitats, leading to rapid diversification of species.
5. Outline the hypothesized sequence of events leading to life:
- Formation of simple organic molecules → polymerization into complex molecules → formation of protocells → evolution of self-replicating molecules (RNA) → development of cellular life.
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Topic 10: Prokaryotes
Learning Outcomes:
1. Describe structural and functional adaptations contributing to prokaryotic success:
- Cell wall: Provides structural support and protection.
- Capsule: Helps adhere to surfaces and evade the immune system.
- Endospores: Allow survival in extreme conditions.
- Flagella: Enable motility.
- Simple internal organization: Lack of membrane-bound organelles; small circular chromosomes and plasmids.
2. Identify the basis of genetic diversity in prokaryotes:
- Rapid reproduction: Binary fission leads to many generations in a short time.
- Mutations: Accumulate quickly due to rapid reproduction.
- Genetic recombination: Transformation, transduction, and conjugation.
3. Classify prokaryotic taxa by nutritional modes:
- Photoautotrophs: Use light energy and CO₂.
- Chemoautotrophs: Use inorganic chemicals and CO₂.
- Photoheterotrophs: Use light energy and organic compounds.
- Chemoheterotrophs: Use organic compounds for energy and carbon.
4. Identify prokaryote taxon groups from their defining characteristics:
- Proteobacteria: Gram-negative, diverse metabolic strategies.
- Chlamydias: Obligate intracellular parasites.
- Spirochetes: Helical shape, corkscrew movement.
- Cyanobacteria: Oxygen-producing photoautotrophs.
- Gram-positive bacteria: Thick peptidoglycan layer.
5. Define ecological interactions involving prokaryotes:
- Mutualism: Both species benefit (e.g., gut bacteria in humans).
- Commensalism: One species benefits, the other is unaffected.
- Parasitism: One species benefits at the expense of the other.
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Topic 11: Origin of Eukaryotes
Learning Outcomes:
1. Differentiate eukaryotes from prokaryotes:
- Eukaryotes have a nucleus, membrane-bound organelles, linear chromosomes, and are generally larger.
- Prokaryotes lack a nucleus, have circular chromosomes, and are smaller.
2. Describe the endosymbiont theory for the origin of eukaryotes:
- Mitochondria and chloroplasts originated from free-living prokaryotes (α-proteobacteria and cyanobacteria, respectively) that were engulfed by ancestral eukaryotic cells.
3. Differentiate between primary and secondary endosymbiosis:
- Primary: Engulfment of a prokaryote by a eukaryotic cell (e.g., mitochondria and chloroplasts).
- Secondary: Engulfment of a eukaryotic cell by another eukaryotic cell (e.g., some algae with plastids).
4. Identify factors contributing to protist diversity:
- Endosymbiosis, varied nutritional modes (photoautotrophy, chemoheterotrophy, mixotrophy), and diverse reproductive strategies.
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Topic 12: Diversity of Protists
Learning Outcomes:
1. Recall example protist groups from the four protist supergroups:
- Excavata: Diplomonads, Parabasalids, Euglenozoans.
- SAR: Diatoms, Brown algae, Apicomplexans, Ciliates.
- Archaeplastida: Red algae, Green algae.
- Unikonta: Amoebozoans, Opisthokonts.
2. Classify protist taxa using characteristic traits:
- Excavata: Feeding groove, modified mitochondria.
- SAR: Alveoli, photosynthetic and heterotrophic forms.
- Archaeplastida: Chloroplasts from primary endosymbiosis.
- Unikonta: Single flagellum or amoeboid movement.
3. Identify protist sister taxa of animals, plants, and fungi:
- Animals: Choanoflagellates.
- Plants: Green algae (Charophytes).
- Fungi: Nucleariids.
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Topic 13: Evolution of Plants
Learning Outcomes:
1. Identify traits of plants shared with other protists:
- Chloroplasts with chlorophyll a and b, cellulose cell walls, and multicellularity.
2. Describe the benefits, challenges, and adaptations of terrestrial life for plants:
- Benefits: Increased sunlight, abundant CO₂, and reduced competition.
- Challenges: Desiccation, lack of structural support.
- Adaptations: Cuticle, stomata, vascular tissue, roots, and leaves.
3. Describe the shared derived traits of plants:
- Alternation of generations, multicellular dependent embryos, walled spores, apical meristems, and cuticle.
4. Summarize the origin and diversification of plants:
- Evolved from charophyte algae ~470 mya; diversified into nonvascular, seedless vascular, and seed plants.
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Topic 14: Nonvascular Plants (Bryophytes)
Learning Outcomes:
1. Recall the phyla of nonvascular plants:
- Hepatophyta: Liverworts.
- Bryophyta: Mosses.
- Anthocerophyta: Hornworts.
2. Describe the characteristics of bryophytes:
- Lack true vascular tissue, lignin, and roots; absorb water through surfaces; gametophyte dominant.
3. Explain the life cycle of a bryophyte:
- Haploid gametophyte produces gametes; fertilization requires water; diploid sporophyte grows from gametophyte and produces spores.
4. Contrast the dependency of bryophytes on water for fertilization and dispersal with that of charophytes:
- Bryophytes require water for fertilization (flagellated sperm); charophytes disperse via water currents.
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Topic 15: Seedless Vascular Plants
Learning Outcomes:
1. Define the shared derived traits of vascular plants:
- Vascular tissue (xylem and phloem), dominant sporophyte, well-developed roots and leaves.
2. Describe the characteristics of extant vascular plants and seedless vascular plants:
- Extant vascular plants: Have true roots, leaves, and vascular tissue.
- Seedless vascular plants: Ferns, horsetails, and lycophytes; reproduce via spores.
3. Explain the life cycle of a fern:
- Sporophyte dominant; produces spores via meiosis; spores develop into gametophytes; fertilization requires water.
4. Identify the taxa of seedless vascular plants:
- Lycophyta: Club mosses, spike mosses, quillworts.
- Monilophyta: Ferns, horsetails, whisk ferns.
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Topic 16: Gymnosperms
Learning Outcomes:
1. Define the shared derived traits of seed plants:
- Reduced gametophytes, heterospory, ovules, pollen, and seeds.
2. Contrast pollination in seed plants with fertilization in seedless plants:
- Seed plants use pollen for fertilization; seedless plants require water for fertilization.
3. Explain the evolutionary benefits of seed dispersal as compared to spore dispersal:
- Seeds provide protection, nutrients, and long-distance dispersal.
4. Identify the taxa of gymnosperms:
- Cycadophyta: Cycads.
- Ginkgophyta: Ginkgo.
- Gnetophyta: Gnetophytes.
- Coniferophyta: Conifers.
5. Explain the life cycle of a conifer:
- Sporophyte dominant; produces male and female cones; pollen is wind-dispersed; seeds develop in female cones.
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Topic 17: Angiosperms
Learning Outcomes:
1. Define the shared derived traits of angiosperms:
- Flowers, fruits, and double fertilization.
2. Describe the structure and function of flowers:
- Structure: Sepals, petals, stamens (male), carpels (female).
- Function: Reproduction via pollination and fertilization.
3. Explain the life cycle of angiosperms:
- Sporophyte dominant; flowers produce gametophytes; double fertilization produces a zygote and endosperm.
4. Explain the adaptive advantages of angiosperm fertilization:
- Efficient pollination, seed dispersal via fruits, and rapid reproduction.
5. Describe self-fertilization and the mechanisms angiosperms have evolved to avoid self-fertilization:
- Self-fertilization leads to inbreeding; mechanisms include dioecy, self-incompatibility, and temporal separation of male and female phases.
6. Differentiate between sexual and asexual reproduction in angiosperms:
- Sexual: Involves flowers, pollination, and seeds.
- Asexual: Vegetative reproduction (e.g., runners, bulbs).
7. Identify angiosperm taxa:
- Monocots: Grasses, lilies, orchids.
- Eudicots: Roses, sunflowers, beans.
Here is a summary of the learning objectives for Topic 18, focusing on the Kingdom Fungi:
1. Define the characteristics of fungi:
- Fungi are eukaryotic, absorptive chemoheterotrophs that obtain nutrients by secreting enzymes to break down complex organic materials externally and then absorbing the simpler molecules.
- They typically have cell walls made of chitin and grow as multicellular filaments called hyphae, which form a network known as mycelium.
- Fungi reproduce via spores, which can be produced asexually (mitosis) or sexually (meiosis).
2. Explain how fungal body structures support absorptive nutrition:
- The filamentous structure of hyphae maximizes the surface area-to-volume ratio, allowing for efficient enzyme secretion and nutrient absorption.
- Hyphae grow at their tips, enabling fungi to explore and colonize new food sources.
- The mycelium acts as a nutrient-absorbing network, spreading through soil or other substrates to access organic material.
3. Describe the generalized life cycle of fungi (including asexual and sexual reproduction):
- Fungi have a haploid-dominant life cycle, with most of their life spent in the haploid (\(1n\)) stage.
- Asexual reproduction occurs through the production of spores via mitosis or through fragmentation and budding.
- Sexual reproduction involves the fusion of hyphae from different mating types, leading to plasmogamy (cytoplasm fusion) and karyogamy (nuclear fusion), followed by meiosis to produce genetically diverse spores.
- Many fungi have a heterokaryotic stage, where genetically distinct haploid nuclei coexist in the same cell before nuclear fusion.
4. Distinguish between fungal phyla using their characteristics:
- Chytridiomycota (Chytrids): Unicellular or multicellular, with flagellated spores (zoospores). Found in aquatic or moist environments.
- Zoopagomycota (Zoopagomycetes): Parasitic or commensal, with coenocytic hyphae and non-flagellated spores.
- Mucoromycota (Mucoromycetes): Fast-growing decomposers, including black bread mold. Some form mycorrhizae with plants.
- Ascomycota (Ascomycetes): "Sac fungi" that produce sexual spores (ascospores) in sac-like structures called asci. Includes yeasts, molds, and morels.
- Basidiomycota (Basidiomycetes): "Club fungi" that produce sexual spores (basidiospores) on club-shaped structures called basidia. Includes mushrooms, puffballs, and shelf fungi.
5. Describe ecological interactions involving fungi:
- Decomposers: Fungi break down dead organic matter, recycling nutrients back into ecosystems.
- Mutualists: Fungi form symbiotic relationships with plants (mycorrhizae), algae, and cyanobacteria (lichens), enhancing nutrient exchange and plant health.
- Pathogens: Some fungi are parasitic, causing diseases in plants, animals, and humans. Examples include ergot in cereals, Dutch elm disease, and athlete's foot.
- Animal-fungus mutualisms: Fungi assist in digestion for some animals (e.g., cellulose-digesting fungi in ruminants) and are cultivated by insects like leafcutter ants.
These objectives provide a comprehensive understanding of the biology, reproduction, and ecological roles of fungi, which are essential for ecosystem function and human welfare.