Study Guide: Fungi, Vascular Plant Structure, Growth, Transport, and Responses

Chapter 31: Fungi (Structure, Function, and Growth)

General Characteristics of Fungi

Fungi are a diverse group of eukaryotic organisms that play essential roles in ecosystems as decomposers, mutualists, and pathogens.

• Hyphae: Thread-like filaments that make up the body of a fungus. Collectively, hyphae form a mycelium.

• Mycelium: A network of hyphae that increases surface area for nutrient absorption.

• Cell Walls: Composed primarily of chitin, providing structural support.

• Nutrition: Fungi are heterotrophs that absorb nutrients from their environment through external digestion.

Fungal Life Cycles and Reproduction

• Fungi reproduce via spores, which can be produced sexually or asexually.

• Sexual reproduction involves plasmogamy (fusion of cytoplasm), karyogamy (fusion of nuclei), and meiosis.

• Asexual reproduction often involves mitotic production of spores.

Fungal Diversity and Ecological Roles

• Major Groups: Chytrids, zygomycetes, glomeromycetes, ascomycetes, and basidiomycetes.

• Mutualists: Mycorrhizae (fungi-plant associations) and lichens (fungi-algae/cyanobacteria associations).

• Decomposers: Break down organic matter, recycling nutrients in ecosystems.

• Pathogens: Cause diseases in plants and animals.

Fungal Structure and Growth

• Hyphal growth occurs at the tips, allowing fungi to rapidly colonize substrates.

• Septate hyphae have cross-walls (septa); coenocytic hyphae lack septa.

Fungi in Biotechnology and Medicine

• Fungi are sources of antibiotics (e.g., penicillin), food products (e.g., yeast in bread and beer), and model organisms in research.

Chapter 35: Vascular Plant Structure, Growth, and Development

Overview of Plant Organs and Tissues

Vascular plants have three main organs: roots, stems, and leaves, each with specialized tissues for support, transport, and photosynthesis.

• Roots: Anchor the plant and absorb water and minerals.

• Stems: Support leaves and reproductive structures; contain vascular tissues for transport.

• Leaves: Main site of photosynthesis; structure maximizes light capture and gas exchange.

Plant Tissue Systems

• Dermal Tissue: Protective outer covering (epidermis, periderm).

• Vascular Tissue: Xylem (water transport) and phloem (sugar transport).

• Ground Tissue: Functions in photosynthesis, storage, and support.

Primary and Secondary Growth

• Primary Growth: Increases length via apical meristems (roots and shoots).

• Secondary Growth: Increases girth via lateral meristems (vascular cambium and cork cambium).

Meristems and Development

• Meristems: Regions of undifferentiated cells that divide and differentiate into various tissues.

• Indeterminate Growth: Many plants grow throughout their lives due to persistent meristem activity.

Leaf, Stem, and Root Anatomy

• Monocots and eudicots differ in arrangement of vascular bundles and tissues.

• Secondary growth forms wood and bark in woody plants.

Chapter 36: Resource Acquisition and Transport in Vascular Plants

Transport Mechanisms in Plants

Plants move water, minerals, and sugars through specialized tissues using physical and physiological processes.

• Xylem: Transports water and minerals from roots to shoots via transpiration and cohesion-tension mechanism.

• Phloem: Transports sugars from sources (leaves) to sinks (roots, fruits) via pressure-flow mechanism.

Water and Mineral Uptake

• Root hairs increase surface area for absorption.

• Mycorrhizal associations enhance nutrient uptake.

Transpiration and Stomatal Regulation

• Transpiration drives water movement; regulated by stomata opening and closing.

• Guard cells control stomatal aperture in response to environmental signals.

Adaptations for Resource Acquisition

• Leaf modifications, root adaptations, and mutualistic relationships improve efficiency in various environments.

Key Equations

• Water potential ($\Psi$): $\Psi = \Psi_s + \Psi_p$

• Pressure-flow hypothesis for phloem transport: $\text{Flow rate} = \frac{\Delta P}{R}$

Chapter 39: Plant Responses to Internal and External Signals

Plant Hormones and Signal Transduction

Plants use hormones and signaling pathways to coordinate growth, development, and responses to stimuli.

• Auxins: Promote cell elongation, apical dominance, and root formation.

• Gibberellins: Stimulate stem elongation, seed germination, and flowering.

• Cytokinins: Promote cell division and delay senescence.

• Abscisic Acid (ABA): Induces stomatal closure during drought stress.

• Ethylene: Regulates fruit ripening and response to mechanical stress.

Photoreceptors and Tropisms

• Phototropism: Growth toward light, mediated by auxin redistribution.

• Gravitropism: Growth in response to gravity.

• Phytochromes: Light receptors that regulate seed germination and shade avoidance.

Plant Defense Mechanisms

• Physical barriers (e.g., thorns, cuticle) and chemical defenses (e.g., secondary metabolites).

• Systemic acquired resistance (SAR) provides long-term protection against pathogens.

Environmental Responses

• Plants respond to drought, flooding, salt, heat, and cold via physiological and molecular changes.

Summary Table: Major Plant Hormones and Their Functions

Hormone	Main Functions
Auxin	Cell elongation, apical dominance, root initiation
Gibberellin	Stem elongation, seed germination, flowering
Cytokinin	Cell division, delay of senescence
Abscisic Acid (ABA)	Stomatal closure, seed dormancy
Ethylene	Fruit ripening, response to mechanical stress

Additional info:

• This study guide is based on a summary of exam topics and learning objectives for a General Biology course, covering fungi and plant biology chapters relevant to structure, function, transport, and signaling.

• For each chapter, students should be able to describe structures, processes, and adaptations, and compare major groups or mechanisms as outlined above.