Chapter 28: Protists

General Features of Protists

Protists are a diverse group of mostly unicellular eukaryotic organisms. They exhibit a wide range of structural and functional characteristics.

• Cellular Organization: Most protists are unicellular, but some are multicellular or colonial.

• Habitat: Found in aquatic environments, moist terrestrial habitats, and as symbionts.

• Nutrition: Can be autotrophic (photosynthetic), heterotrophic, or mixotrophic.

• Movement: Use flagella, cilia, or pseudopodia for locomotion.

• Reproduction: Both sexual and asexual reproduction are common.

Diversity and Endosymbiosis

The diversity of protists is largely attributed to endosymbiotic events, where one cell engulfed another, leading to organelles like mitochondria and chloroplasts.

• Primary Endosymbiosis: Origin of mitochondria and chloroplasts.

• Secondary Endosymbiosis: Some protists acquired plastids by engulfing other eukaryotes.

• Example: Euglenids have chloroplasts from secondary endosymbiosis.

Major Groups of Eukaryotes

Eukaryotes are classified into four supergroups, some of which contain only protists.

• Excavata (mostly protists)

• SAR (Stramenopiles, Alveolates, Rhizarians; mostly protists)

• Archaeplastida (includes plants and some protists)

• Unikonta (includes fungi, animals, and some protists)

Groups can be:

• Monophyletic: All descendants from a common ancestor.

• Paraphyletic: Some, but not all, descendants from a common ancestor.

• Polyphyletic: Members from multiple ancestors.

Example: Archaeplastida is monophyletic; "protists" as a group is paraphyletic.

Chapter 29: Plant Diversity I – How Plants Colonized Land (Seedless Plants)

Major Developments in Plant Evolution

Plants evolved from green algae and developed adaptations to survive on land.

• Adaptations: Cuticle, stomata, multicellular gametangia, sporopollenin, vascular tissue (in later groups).

• Shared Traits with Algae: Chlorophylls a and b, cell walls of cellulose.

Alternation of Generations

Plants exhibit alternation of generations, alternating between haploid gametophyte and diploid sporophyte stages.

• Sporophyte: Diploid, produces spores by meiosis.

• Gametophyte: Haploid, produces gametes by mitosis.

• Fertilization: Fusion of gametes forms diploid zygote.

• Meiosis: Occurs in sporophyte to produce haploid spores.

Mosses/Non-Vascular vs Vascular Seedless Plants

Plants are classified based on the presence of vascular tissue and dominant life stage.

• Non-Vascular (Bryophytes): Mosses, liverworts, hornworts; gametophyte dominant; require water for reproduction.

• Vascular Seedless Plants: Ferns, horsetails, club mosses; sporophyte dominant; have vascular tissue.

Example: Mosses are non-vascular; ferns are vascular seedless plants.

Importance of Vascular Tissue

Vascular tissue (xylem and phloem) allowed plants to grow taller and transport water and nutrients efficiently.

• Xylem: Transports water and minerals.

• Phloem: Transports sugars and organic compounds.

Global Climate Change and Fossil Fuels

Burning fossil fuels releases CO2, contributing to global climate change.

• Fossil Fuels: Derived from ancient plant material.

• Impact: Increased greenhouse gases, warming climate.

Chapter 30: Plant Diversity II – The Evolution of Seed Plants (Gymnosperms and Angiosperms)

Seeds and Pollen as Adaptations

Seeds and pollen allowed plants to reproduce without water and colonize dry environments.

• Seed: Embryo, food supply, protective coat.

• Pollen: Delivers sperm to ovule without water.

Heterospory

Heterospory is the production of two types of spores: microspores (male) and megaspores (female).

• Evolutionary Advantage: Specialization of gametophytes, increased reproductive success.

Gymnosperms: Characteristics and Groups

Gymnosperms are seed plants with "naked" seeds, often in cones.

• Male Cones: Produce pollen.

• Female Cones: Produce ovules and seeds.

• Major Groups: Cycads, Ginkgo, Gnetophytes, Conifers.

Angiosperms: Success and Structures

Angiosperms (flowering plants) are the most diverse group of plants.

• Flowers: Specialized for reproduction.

• Fruits: Protect seeds and aid in dispersal.

• Double Fertilization: Unique to angiosperms; one sperm fertilizes egg, another forms endosperm.

• Key Drivers: Coevolution with pollinators, rapid diversification.

• Major Groups: Monocots (one cotyledon), Eudicots (two cotyledons).

Seed Plant Products and Threats

• Major Crops: Wheat, rice, maize, potatoes, cassava, and sweet potatoes provide most human calories.

• Threats: Habitat loss, climate change, invasive species.

Derived Traits of Seed Plants

• Reduced gametophytes

• Heterospory

• Ovules

• Pollen

• Seeds

Chapter 31: Fungi

Feeding and Structure of Fungi

Fungi are heterotrophic organisms that absorb nutrients from their environment.

• Structure: Composed of hyphae (filamentous cells) forming a mycelium.

• Feeding: Secrete enzymes to break down organic matter.

Reproduction in Fungi

Fungi reproduce both sexually and asexually, with complex life cycles.

• Haploid Stage: Most of the life cycle; spores germinate into haploid mycelium.

• Heterokaryotic Stage: Cells contain two or more nuclei from different parents.

• Diploid Stage: Brief; occurs after nuclear fusion.

• Sexual Reproduction: Involves plasmogamy (fusion of cytoplasm), karyogamy (fusion of nuclei), and meiosis.

• Asexual Reproduction: Spores produced by mitosis.

Fungi Evolution and Phylogeny

Fungi are more closely related to animals than to protists, based on molecular evidence.

• Monophyletic Group: All fungi share a common ancestor.

• Adaptations to Land: Resistant spores, symbiosis with plants.

Major Groups of Fungi

• Chytrids: Ancestral, aquatic, flagellated spores.

• Zygomycetes: Terrestrial, zygosporangia.

• Glomeromycetes: Form arbuscular mycorrhizae with plants.

• Ascomycetes: Sac fungi, produce spores in asci.

• Basidiomycetes: Club fungi, produce spores on basidia.

Example: Yeasts (ascomycetes), mushrooms (basidiomycetes).

Roles and Uses of Fungi

• Ecological Roles: Decomposers, mutualists (mycorrhizae, lichens), pathogens.

• Practical Uses: Antibiotics (penicillin), food production (bread, cheese), biotechnology.

Additional info: These notes expand on brief study guide points to provide academic context, definitions, and examples for exam preparation.