Exam 1 Study Guide: Prokaryotes, Protists, Plant Diversity, Fungi, and Vascular Plant Structure

CHAPTER 27: Bacteria and Archaea

Overview of Prokaryotes

Prokaryotes, comprising the domains Bacteria and Archaea, are unicellular organisms that thrive in diverse and often extreme environments. They exhibit a variety of shapes and sizes and play essential roles in ecological systems.

• Domains: Bacteria and Archaea

• Habitats: Acidic, salty, cold, hot, and other extreme environments

• Cell Size: 0.5–5 µm

• Shapes: Spheres (cocci), rods (bacilli), spirals

Cell Wall Structure: Gram-Positive vs. Gram-Negative

• Gram-Positive Bacteria: Thick peptidoglycan cell wall; stains purple with Gram stain

• Gram-Negative Bacteria: Thin peptidoglycan layer, outer membrane with lipopolysaccharides; stains red

Prokaryotic Structures and Functions

• Capsule: Sticky polysaccharide/protein layer for protection and adherence

• Endospore: Dormant, tough structure for surviving harsh conditions

• Fimbriae: Hairlike appendages for attachment

• Pili (Sex Pili): Longer appendages for DNA exchange

• Flagella: Whip-like structures for movement

Reproduction and Genetic Diversity

• Binary Fission: Rapid asexual reproduction (every 1–3 hours)

• Genetic Diversity Mechanisms:

  • Rapid reproduction

  • Mutation (low rates, but significant due to large populations)

  • Genetic recombination

Nutritional Modes and Major Bacterial Groups

• Major Groups: Proteobacteria, Chlamydias, Spirochetes, Cyanobacteria, Gram-positive bacteria

Proteobacteria

• Gram-negative; includes photoautotrophs, chemoautotrophs, heterotrophs

• Subgroups: Alpha, Beta, Gamma, Delta, Epsilon

Chlamydias

• Obligate intracellular parasites of animal cells

• Example: Chlamydia trachomatis causes blindness and urethritis

Spirochetes

• Helical, gram-negative heterotrophs

• Examples: Treponema pallidum (syphilis), Borrelia burgdorferi (Lyme disease)

Cyanobacteria

• Gram-negative photoautotrophs; generate O2

• Major component of phytoplankton

Gram-Positive Bacteria

• Includes actinomycetes (decomposers), Bacillus anthracis (anthrax), Clostridium botulinum (botulism), Staphylococcus and Streptococcus species, mycoplasmas (smallest cells, lack cell walls)

Archaea

• Share traits with both bacteria and eukaryotes

• Extremophiles:

  • Extreme halophiles: Thrive in high-salt environments

  • Extreme thermophiles: Thrive in high-temperature environments

  • Methanogens: Produce methane, live in anaerobic environments (e.g., swamps)

Ecological Roles of Prokaryotes

• Mutualists: Aid in digestion (e.g., gut bacteria)

• Pathogens: Cause diseases (e.g., Lyme disease)

• Endotoxins: Released when bacteria die; cause disease

• Exotoxins: Secreted by living bacteria; cause disease

CHAPTER 28: Protists

Introduction to Protists

Protists are a diverse group of mostly unicellular eukaryotes. They exhibit a wide range of nutritional modes, reproductive strategies, and ecological roles.

Nutritional Modes

• Photoautotrophs (photosynthetic)

• Heterotrophs (ingest organic material)

• Mixotrophs (combine photosynthesis and heterotrophy)

Reproduction and Life Cycles

• Both sexual and asexual reproduction

• Alternation of generations: Multicellular haploid and diploid forms

Major Supergroups of Protists

• Excavata

• SAR (Stramenopiles, Alveolates, Rhizarians)

• Archaeplastida

• Unikonta

Excavata

• Characterized by an "excavated" feeding groove

• Includes:

  • Diplomonads (lack plastids, anaerobic)

  • Parabasalids (lack plastids, anaerobic)

  • Euglenozoans (diverse: heterotrophs, autotrophs, mixotrophs, parasites)

SAR

• Named for Stramenopiles, Alveolates, Rhizarians

Stramenopiles

• Photosynthetic organisms with hairy and smooth flagella

• Includes:

  • Diatoms (glass-like cell wall of silicon dioxide)

  • Golden algae (biflagellate)

  • Brown algae (largest, most complex; "seaweeds")

Alveolates

• Membrane-enclosed sacs (alveoli) under plasma membrane

• Includes:

  • Dinoflagellates (two flagella, cellulose plates)

  • Apicomplexans (animal parasites)

  • Ciliates (move using cilia)

Rhizarians

• Many are amoebas with threadlike pseudopodia

• Includes:

  • Radiolarians (marine)

  • Forams (porous shells called tests)

  • Cercozoans (amoeboid and flagellated)

Archaeplastida

• Includes red algae, green algae, and plants

• Red algae: Reddish due to phycoerythrin pigment

• Green algae: Grass-green chloroplasts; includes charophytes and chlorophytes

Unikonta

• Includes animals, fungi, and some protists

• Groups:

  • Amoebozoans (lobe- or tube-shaped pseudopodia; slime molds, tubulinids, entamoebas)

  • Opisthokonts (animals, fungi, related protists)

Ecological Roles of Protists

• Symbionts: Benefit hosts (e.g., dinoflagellates in coral, wood-digesting protists in termites)

• Producers: Form the base of aquatic food webs

CHAPTER 29 & 30: Plant Diversity

Key Traits of Plants

• Alternation of generations

• Multicellular, dependent embryos

• Walled spores produced in sporangia

• Multicellular gametangia

• Apical meristems

Alternation of Generations

• Plants alternate between multicellular haploid (gametophyte) and diploid (sporophyte) generations

• Gametophyte produces gametes by mitosis

• Fusion of gametes forms diploid sporophyte, which produces spores by meiosis

Multicellular, Dependent Embryos

• Embryo retained within female gametophyte tissue

• Nutrients transferred via placental transfer cells

Walled Spores in Sporangia

• Sporophyte produces spores in sporangia

• Spore walls contain sporopollenin for resistance

Multicellular Gametangia

• Archegonia (female): Produce single non-motile egg

• Antheridia (male): Produce and release sperm

Apical Meristems

• Regions of cell division at tips of roots and shoots

• Enable growth and differentiation into various tissues

Major Plant Groups

• Nonvascular Plants (Bryophytes): Liverworts, mosses, hornworts

• Vascular Plants: Seedless (lycophytes, monilophytes) and seed plants (gymnosperms, angiosperms)

• Seed Plants: Gymnosperms (naked seeds), Angiosperms (seeds in flowers)

• Monocots and Dicots (angiosperm subgroups)

Plant Organs and Structures

• Roots: Anchor plant, absorb water/nutrients

• Stems: Support and orient plant for photosynthesis

• Leaves: Increase surface area for photosynthesis; types include microphylls (single vein) and megaphylls (branched veins)

• Seeds: Embryo and nutrients in protective coat; gymnosperms (naked seeds), angiosperms (seeds in flowers)

• Flowers: Specialized for sexual reproduction; organs include sepals, petals, stamens, carpels

• Fruits: Mature ovary; aids in seed dispersal; types include simple, aggregate, multiple, accessory fruits

CHAPTER 31: Fungi

Introduction to Fungi

Fungi are heterotrophic eukaryotes that absorb nutrients from their environment. They play crucial roles as decomposers, parasites, and mutualists in ecosystems.

Fungal Lifestyles

• Decomposers: Break down nonliving organic material (e.g., cellulose, lignin)

• Parasites: Absorb nutrients from living hosts; can be plant pathogens

• Mutualists: Form beneficial relationships with plants (mycorrhizae), animals, algae, or cyanobacteria

Fungal Body Structure

• Most fungi are multicellular filaments (hyphae); some are single-celled (yeasts)

• Some species can alternate between filamentous and yeast forms

Fungal Reproduction

• Produce spores sexually or asexually

• Sexual reproduction involves pheromones and transient diploid stages

• Asexual reproduction: Molds (spores by mitosis), yeasts (budding)

CHAPTER 35: Vascular Plant Structure, Growth, and Development

Plant Organs: Structure and Function

• Roots: Anchor plant, absorb minerals/water, store carbohydrates

• Stems: Elongate and orient shoot for photosynthesis

• Leaves: Intercept light, exchange gases, dissipate heat, defend against herbivores/pathogens

Plant Tissue Systems

• Dermal: Outer protective covering; in nonwoody plants, consists of epidermis with waxy cuticle

• Vascular: Transport system; xylem (water/minerals up), phloem (sugars down)

• Ground: Functions in storage, photosynthesis, support; includes pith (internal) and cortex (external)

Common Plant Cell Types

• Parenchyma: Thin, flexible walls; metabolic functions; can divide/differentiate

• Collenchyma: Unevenly thickened walls; support young shoots; living at maturity

• Sclerenchyma: Thick, lignified walls; support; dead at maturity; includes sclereids (short, irregular) and fibers (long, slender)

• Water-conducting cells (xylem): Tracheids (long, thin, tapered ends, all vascular plants), vessel elements (form vessels, angiosperms); both dead at maturity

• Sugar-conducting cells (phloem): Sieve cells (seedless/gymnosperms), sieve-tube elements (angiosperms, alive but lack organelles, connected to companion cells)

Plant Growth: Primary vs. Secondary

• Primary Growth: Lengthening; occurs at apical meristems (root/shoot tips)

• Secondary Growth: Thickening; occurs at lateral meristems (woody plants)