Advanced Biology - Plant Classification and Systems

Advanced Biology Vocabulary

Plant Classification Terms

• classification: A systematic method of categorizing organisms.

• taxon: A level of classification; the basic level is species; taxa is the plural.

• taxonomy: Science of naming and classifying organisms.

• Carl Linnaeus: Developed the scientific naming system still used today.

• hierarchy: Multilevel scale in classification where each level is contained in the next level up.

• domain, kingdom, genus, species: Levels of biological classification in ascending order of specificity.

• binomial nomenclature: A system of naming species with a two-part scientific name.

Plant Concepts

• alternation of generations: A life cycle pattern with both haploid and diploid phases in a plant's life cycle.

• angiosperm: Flowering plants that produce seeds enclosed in fruit.

• annual: A plant that completes its lifecycle in one year.

• biennial: A plant that takes two years to complete its lifecycle.

• bryophyte: Non-vascular land plants, such as mosses.

• carpel: The ovule-producing part of a flower.

• cuticle: A waxy layer that covers plant leaves to reduce water loss.

• chlorophyll: The green pigment in plants that captures light for photosynthesis.

• chloroplast: An organelle where photosynthesis occurs.

• cotyledon: The first leaves that appear on a plant embryo.

• dermal tissue: Protective outer covering of a plant.

• dicot: Flowering plants with two cotyledons.

• dormancy: A state of inactivity in seeds or plants during unfavorable conditions.

• double fertilization: A feature in angiosperms where one sperm fertilizes the egg and another forms the endosperm.

• epidermis: The outer layer of cells in a plant.

• fibrous root: A root system with many thin roots.

• flower: The reproductive structure of angiosperms.

• fruit: Mature ovary that contains seeds.

• gametophyte: The haploid phase that produces gametes.

• germination: The process by which a seed develops into a new plant.

• gravitropism: Growth response of a plant to gravity.

• guard cell: Cells that surround stomata and control their opening and closing.

• gymnosperm: Seed-producing plants that do not have flowers.

• hormone: Chemical messenger that regulates plant growth and responses.

• leaf: The main photosynthetic organ of a plant.

• meristem: Regions of undifferentiated cells responsible for plant growth.

• mesophyll: The middle layer of leaf tissue where photosynthesis occurs.

• monocot: Flowering plants with one cotyledon.

• node: A point on a plant stem where leaves are attached.

• nonvascular: Plants like mosses that lack a vascular system for transporting water and nutrients.

• ovary: The part of the flower that holds ovules.

• pollen: The fertilizing agent of flowering plants containing the male gamete.

• pollination: The transfer of pollen to the stigma of a flower.

• perennial: Long-lived plants that can survive for more than two years.

• phloem: Vascular tissue that transports sugars and nutrients.

• photoperiodism: The response of a plant to the length of day and night.

• photosynthesis: The process through which plants convert light energy into chemical energy, producing oxygen.

• spore: A haploid cell capable of developing into a gametophyte.

• sporophyte: The diploid phase of a plant life cycle that produces spores through meiosis.

• stamen: The male reproductive structure of flowers.

• stigma: Part of the female flower that receives pollen.

• stomata: Tiny openings in leaves for gas exchange.

• taproot: A single, thick, central root.

• transpiration: The process of water vapor loss from plant leaves.

• vascular tissue: The conducting tissue in plants, primarily xylem and phloem.

• vegetative reproduction: A form of asexual reproduction in plants.

• xylem: Vascular tissue that conducts water and dissolved nutrients upward from the roots.

Cellular Energetics (Photosynthesis and Cellular Respiration)

• aerobic respiration: The process of producing cellular energy involving oxygen.

• anaerobic respiration: The process of producing cellular energy without oxygen.

• ATP: Adenosine triphosphate, the energy currency of cells.

• Calvin cycle: The phase of photosynthesis that converts carbon dioxide into sugars.

• carbon dioxide: A reactant in photosynthesis which is taken from the atmosphere.

• chemical reaction: A process that leads to the transformation of one set of chemical substances to another.

• electron transport chain: A series of proteins that transfer electrons to create ATP.

• fermentation: A metabolic process that converts sugars to acids, gases, or alcohol.

• glucose: A simple sugar that is the main product of photosynthesis.

• glycolysis: The first step of cellular respiration that breaks down glucose.

• Kreb cycle (citric acid cycle): A series of enzymatic reactions in cellular respiration.

• light reaction: The phase in photosynthesis that captures solar energy.

• mitochondria: The powerhouse of the cell where respiration occurs.

• photosynthesis: The process in which plants convert sunlight into chemical energy.

• product: The substance obtained from a chemical reaction.

• reactant: The substance consumed in a chemical reaction.

• stroma: The fluid-filled space surrounding the thylakoids in chloroplasts.

• thylakoid: Membranous structures within chloroplasts where light reactions occur.

The Linnaean System of Classification

• Developed by Linnaeus, the scientific naming system is hierarchical and based on physical similarities.

• Taxonomic hierarchy: Includes levels such as Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

  • Most general/least specific: Kingdom

  • Most specific/least diverse: Species.

• The use of the term taxon for a particular group of organisms provides clarity and a common language for scientists.

Scientific Naming

• Common names can be confusing due to overlap among organisms (e.g., Cougar also known as Mountain Lion, Puma).

• Binomial nomenclature assigns a two-part name to each species:

  • Genus: The first part, capitalized and italicized/underlined.

  • Species: The second part, not capitalized but italicized/underlined.

  • Example: Cougar's scientific name is Puma concolor.

Limitations of Linnaean Classification

• Classification systems based solely on physical characteristics may overlook genetic relationships.

• Modern technology allows for molecular comparisons such as nucleotide sequences.

• Homologous characteristics are crucial for accurate classification, while analogous characteristics may occur due to convergent evolution.

Tools for Classifying Organisms

• Dichotomous Key: A series of paired statements that guide identification through yes/no questions until reaching a conclusion.

Domains & Kingdoms

Plant Systems and Interactions

Importance of Plants

• Provide oxygen, food, climate regulation, and soil health.

Basic Needs of Plants

• Sunlight: Essential for photosynthesis.

• Gas exchange: Involves CO2 intake for photosynthesis and O2 release.

• Water: Necessary for photosynthesis and transport.

• Minerals: Important for various plant functions.

Plant Organ Systems

• Organs: Roots, stems, and leaves.

• Tissue Systems: Dermal, ground, vascular.

  • Basic Cell Types: Parenchyma, collenchyma, sclerenchyma.

Structure of Plant Tissues

1. Dermal tissue system: Outer protective layer.

2. Ground tissue system: Functions in photosynthesis and storage.

3. Vascular tissue system: Transports water and nutrients.

Plant Growth Characteristics

• Determinate growth: Animals grow to a certain size.

• Indeterminate growth: Plants continue growing throughout their life.

  • Meristem: Regions of active cell division found in growing tips.

Evolution of Plants

• Plants adapted from aquatic to terrestrial environments.

• Major adaptations for land include moisture retention, resource transport, upright growth, and reproductive strategies.

Adaptations of Land Plants

1. Retaining moisture: Cuticles, stomata.

2. Transporting resources: Vascular systems.

3. Upright growth: Lignin in cell walls for support.

4. Reproducing on land: Pollen and seeds aid in reproduction without water.

Evolution Summary

• Modern land plants evolved from ancient water-dwelling organisms, with important historical fossils seen in species like Cooksonia.

Overview of Plant Kingdom

Major Groups Within Kingdom Plantae

• Green Algae: Simple aquatic organisms, ancestral to land plants.

• Bryophytes (Mosses): Nonvascular land plants, requiring water for reproduction.

• Seedless Pteridophytes (Ferns): Vascular plants that reproduce via spores.

• Seed Plants: Include Gymnosperms and Angiosperms.

Gymnosperms vs. Angiosperms

• Gymnosperms: Naked seeds, including pines and firs; reproduce through cones.

• Angiosperms: Enclosed seeds in fruit, occupy most diverse plant space.

Plant Reproduction

• Vegetative reproduction: Asexual reproduction via parts of the plant (stolons, rhizomes).

• Sexual reproduction: Alternation of generations in plant life cycles.

Life Cycle Summary

• Sporophyte: Diploid phase producing spores.

• Gametophyte: Haploid phase producing gametes (eggs & sperm).

Trends in Plant Evolution

• Gametophytes decrease in size while sporophytes increase.

Angiosperm Structure and Function

Monocots vs. Dicots Characteristics

Monocots

• Cotyledons: One cotyledon in the seed.

• Leaf Venation: Parallel leaf veins.

• Root System: Fibrous root system.

• Stem Structure: Vascular bundles scattered throughout the stem.

• Flower Parts: Floral parts typically in multiples of three.

Dicots

• Cotyledons: Two cotyledons in the seed.

• Leaf Venation: Net-like or branching leaf veins.

• Root System: Taproot system.

• Stem Structure: Vascular bundles arranged in a circle.

• Flower Parts: Floral parts typically in multiples of four or five.

Flower Anatomy

• Composed of four layers: sepals, petals, stamens, and pistils.

  • Function of each part in reproduction defined clearly.

  • Pollination and Fertilization: Process involving pollen on stigma and double fertilization.

Fruits and Seeds

• Ripened ovaries that provide protection and aid in seed dispersal.

• Various fruit types based on adaptation for seed propagation.

Seed Germination

• Dormancy: Inactivity phase that seeds can enter until conditions are suitable.

• Germination: Activation of seeds under favorable conditions leading to growth.

Transport in Plants

Vascular Systems

• Xylem and Phloem: Key components for the transport of water, nutrients, and food throughout the plant.

• Mechanisms of water transport dependent on transpiration, cohesion, and adhesion.

Roles of Roots and Stems in Transport

• Roots absorb nutrients and anchor plants.

• Stems support plant structure and transport materials.

Leaf Structure

• Photosynthesis occurs primarily within the leaves' mesophyll layers.

• Stomata control gas exchange; guard cells regulate their function.

Plant Responses to Environment

Effects of Hormones

• Hormones regulate growth and response to stimuli (light, gravity). Examples of types of plant hormones include:

  • Auxins: Promote stem elongation, root growth, and differentiation, and are involved in phototropism (growth toward light).

  • Gibberellins: Stimulate stem elongation, germination, flowering, and fruit development.

  • Cytokinins: Promote cell division, influence leaf expansion, and delay leaf senescence (aging).

  • Abscisic Acid (ABA): Regulates stomatal closure during drought, promotes seed dormancy, and inhibits growth under unfavorable conditions.

  • Ethylene: Involved in fruit ripening, flower wilting, and leaf fall (abscission).

  • Brassinosteroids: Promote cell expansion and division, enhance plant growth, and are involved in stress responses.

Tropisms

• Phototropism: Growth toward light.

• Gravitropism: Growth responses to gravity.

• Thigmotropism: Touch responses.

Adaptations for Seasonal Changes

• Changes in auxin and ethylene production during fall lead to leaf drop.

Responses to Environmental Stimuli

• Plants respond with growth toward stimuli, maintaining balance between photosynthesis and water retention.