BIOL 108 theme 2 and 3

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.