Internal Plant Anatomy, Transport, and Nutrition Study Guide

Comprehensive vocabulary flashcards covering internal plant anatomy, root and shoot organization, cellular membrane transport mechanisms, xylem and phloem translocation, soil horizons, and plant mineral nutrition.

Vascular Cambium

A layer of actively dividing cells in dicot stems that produces secondary xylem toward the inside and secondary phloem toward the outside, allowing secondary growth to increase stem diameter.

Dicot Stem Vascular Bundles

Vascular bundles arranged in a distinct ring containing vascular cambium, which permits secondary growth and woody tissue formation.

Monocot Stem Vascular Bundles

Vascular bundles scattered throughout the stem that generally lack vascular cambium, preventing secondary growth.

Desert Plant Cortex

A thickened cortex containing specialized water-storage cells that helps plants survive dry conditions.

Parenchyma

Cortex cells responsible for storage and photosynthesis.

Collenchyma

Cortex cells that provide flexible structural support to plant tissues.

Sclerenchyma

Cortex cells that provide strong, rigid support and protection, often forming bundle caps around vascular bundles.

Bundle Caps

Strengthening tissues composed usually of sclerenchyma that surround vascular bundles to provide support and protection.

Early Wood

Light-colored annual growth ring wood that forms during favorable conditions, characterized by larger cells with thinner walls.

Late Wood

Dark-colored annual growth ring wood that forms during less favorable conditions, characterized by smaller cells with thicker walls.

Heartwood

Older, darker, non-functioning xylem located toward the center of a woody plant that primarily provides structural support.

Sapwood

Younger, lighter, functioning xylem that actively transports water and dissolved minerals.

Hardwoods

Wood derived from angiosperms (flowering plants) consisting of vessels, tracheids, and fibers.

Softwoods

Wood derived from gymnosperms (usually conifers) that lacks vessels and fibers and primarily contains tracheids.

Zone of Cell Division

The root tip region where cells actively divide.

Zone of Elongation

The root tip region where newly formed cells increase in length.

Zone of Maturation

The root tip region where cells specialize and differentiate into distinct tissues and where root hairs form.

Root Hairs

Tiny, long and thin extensions of root epidermal cells that increase surface area for the efficient absorption of water and minerals from soil.

Endodermis

The root tissue layer that controls the entry and movement of water and dissolved minerals into the central vascular tissue.

Casparian Strip

A waterproof barrier located within the endodermis that forces water and minerals to pass through selectively permeable cell membranes before entering the xylem.

Pericycle

The root tissue layer situated directly beneath the endodermis from which lateral or branch roots originate.

Dicot Root Anatomy

Internal root arrangement where xylem is organized in a central star shape with little to no central pith.

Monocot Root Anatomy

Internal root arrangement where xylem and phloem are organized in a ring surrounding a central pith.

Velamen

Specialized absorptive epidermal tissue found on aerial roots that takes up moisture directly from the air.

Storage Roots

Modified roots equipped with enlarged storage tissues that store carbohydrates and nutrients.

Guard Cells

The only epidermal cells containing chloroplasts; they regulate gas exchange and water loss by swelling to open stomata and shrinking to close them.

Stomata

Microscopic openings on the leaf epidermis that allow carbon dioxide to enter and oxygen and water vapor to exit.

Palisade Mesophyll

Densely packed leaf ground tissue containing numerous chloroplasts, specialized for absorbing sunlight for photosynthesis.

Spongy Mesophyll

Loosely arranged leaf ground tissue with fewer chloroplasts and extensive air spaces that facilitate gas exchange.

Bulliform Cells

Specialized cells in monocot leaves that deflate upon water loss, causing the leaf to roll or fold inward to reduce surface exposure and transpiration.

Aerenchyma

Specialized plant tissue containing large air spaces that assists in internal gas exchange and buoyancy in aquatic plants such as Elodea.

Primary Metabolites

Essential biological molecules synthesized by plants, including carbohydrates, proteins, lipids, and nucleic acids.

Fluid Mosaic Model

The structural model of the plasma membrane featuring a dynamic double layer of phospholipids in which embedded proteins can move around freely.

Selective Permeability

The property of a membrane allowing specific substances to pass through while blocking others.

Simple Diffusion

The passive net movement of particles directly across a membrane from a higher concentration to a lower concentration without requiring energy.

Facilitated Diffusion

The passive movement of substances down their concentration gradient through transport proteins without requiring ATP.

Osmosis

The net movement of water across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

Active Transport

The movement of substances against their concentration gradient using specialized transport proteins and energy supplied by ATP.

Aquaporins

Membrane transport proteins that form water-selective pores to facilitate the rapid movement of water across biological membranes.

Uniporters

Membrane transport proteins that move a single type of substance across a membrane in one direction.

Symporters

Coupled transport proteins that move two different substances across a membrane simultaneously in the same direction.

Antiporters

Coupled transport proteins that move two different substances across a membrane simultaneously in opposite directions.

Turgor Pressure

The internal hydrostatic pressure exerted by water inside a plant cell pushing outward against the cell wall, maintaining upright posture and cellular firmness.

Turgid

The firm, swollen condition of a plant cell resulting from water entering when placed in a hypotonic solution.

Flaccid

The limp, softened state of a plant cell resulting from no net water movement when placed in an isotonic solution.

Plasmolyzed

The condition of a plant cell placed in a hypertonic solution where excessive water loss causes the plasma membrane to shrink and pull away from the cell wall.

Transpiration

The loss of water vapor from plant tissues, primarily occurring via evaporation from leaf cells through open stomatal pores.

Cohesion-Tension Theory

The scientific explanation for upward water ascent in plants, whereby transpiration generates negative pressure (tension) that pulls a cohesive and adhesive continuous water column upward through the xylem.

Source (Phloem Transport)

A plant organ or tissue where sugars are actively synthesized or mobilized, typically mature photosynthetic leaves.

Sink (Phloem Transport)

A plant organ or tissue where sugars are consumed or stored, such as roots, developing fruits, seeds, and growing tissues.

Pressure-Flow Hypothesis

The mechanism of phloem translocation where ATP-driven loading of sugars at a source draws water in by osmosis, establishing a high turgor pressure that drives bulk flow toward a sink where sugars are unloaded.

Xylem

Vascular tissue composed of dead cells (vessel elements and tracheids) with thick secondary walls and open lumens that transports water and minerals primarily upward.

Phloem

Vascular tissue composed of living cells (sieve tube elements and companion cells) that transports sugars and organic nutrients bidirectionally between sources and sinks.

Mycorrhizal Fungi

Symbiotic root-associated fungi that enhance plant uptake of water and soil minerals, particularly phosphorus.

Nitrogen-Fixing Bacteria

Mutualistic bacteria capable of converting inert atmospheric nitrogen gas into bioavailable nitrogen compounds that plants can assimilate.

Loam

An optimal agricultural soil consisting of a balanced mixture of sand, silt, and clay that harmonizes drainage, moisture retention, and aeration.

Soil Horizons

The distinct vertical layers of a mature soil profile: O (organic matter), A (topsoil), E (leached layer), B (subsoil), C (weathered parent material), and R (solid bedrock).

Macronutrients

The nine chemical elements required by plants in large quantities: Carbon ($C$), Hydrogen ($H$), Oxygen ($O$), Nitrogen ($N$), Phosphorus ($P$), Potassium ($K$), Calcium ($Ca$), Magnesium ($Mg$), and Sulfur ($S$).

Micronutrients

Essential plant elements required only in trace amounts, including Iron ($Fe$), Zinc ($Zn$), Copper ($Cu$), Manganese ($Mn$), Boron ($B$), Chlorine ($Cl$), Molybdenum ($Mo$), and Nickel ($Ni$).

Mobile Nutrients

Plant nutrients (such as nitrogen) that can be translocated to younger tissues during starvation, causing deficiency symptoms to appear first on older, lower leaves.

Immobile Nutrients

Nutrients (such as calcium and iron) that cannot be readily mobilized within the plant, causing deficiency symptoms to manifest first on newer, younger leaves.

Hydroponics

A technique of cultivating plants without soil by immersing the root system directly in water enriched with essential dissolved nutrients.