GAS EXCHANGE AND TRANSPORT IN PLANTS

This set of flashcards contains key vocabulary terms and concepts related to gas exchange and transport in plants, focusing on processes, structures, and functions critical to plant physiology.

Stomata

Small openings on the surface of leaves that allow for gas exchange.

Stomata density

The number of stomata per unit area on a leaf, influencing gas exchange efficiency.

Simple diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration without the aid of membrane proteins.

Facilitated diffusion

The transport of molecules across a membrane via channel or carrier proteins, following the concentration gradient.

Osmosis

The diffusion of water molecules across a selectively permeable membrane.

Active transport

The movement of solutes against their concentration gradient, requiring energy, usually in the form of ATP.

Selective permeability

The property of a membrane that allows certain substances to pass while preventing others.

Fluid mosaic model

A model describing the structure of the plasma membrane as a mosaic of various proteins floating in or on the fluid lipid bilayer.

Phospholipid bilayer

The basic structural component of cellular membranes, consisting of two layers of phospholipids.

Net diffusion

The overall movement of particles from an area of higher concentration to one of lower concentration.

Equilibrium

A state in which the concentration of a solute is the same throughout a solution.

Solute

A substance that is dissolved in a solvent to form a solution.

Solvent

The liquid in which a solute is dissolved to form a solution.

High water concentration

A region where water molecules are more abundant compared to another area.

Low water concentration

A region where water molecules are less abundant compared to another area.

Turgor pressure

The pressure exerted by fluid in the central vacuole against the cell wall of a plant cell.

Isotonic solution

A solution with equal concentration of solutes inside and outside a cell, resulting in no net water movement.

Hypotonic solution

A solution with a lower concentration of solutes compared to the inside of a cell, causing water to move into the cell, potentially leading to lysis.

Hypertonic solution

A solution with a higher concentration of solutes compared to the inside of a cell, leading to water exiting the cell and causing it to shrivel.

Carrier proteins

Proteins that facilitate the transport of specific molecules across a cell membrane.

Channel proteins

Proteins that form openings in the membrane, allowing the passage of specific ions or molecules.

Aquaporins

Specialized channel proteins that facilitate the transport of water across cell membranes.

ATP

Adenosine triphosphate, the primary energy carrier in cells.

Na+/K+ ATPase

An enzyme that pumps sodium out of and potassium into the cell against their concentration gradients.

Vascular plants

Plants that have specialized tissue (xylem and phloem) for the transport of water, minerals, and nutrients.

Xylem

Vascular tissue in plants that transports water and dissolved minerals from roots to shoots.

Phloem

Vascular tissue that transports sugars and other metabolic products downward from the leaves.

Mycorrhizae

Symbiotic associations between fungi and plant roots that enhance nutrient absorption.

Gas exchange

The process by which oxygen and carbon dioxide move in and out of plants, primarily through stomata.

Transpiration

The evaporation of water from plant leaves, which helps in nutrient transport.

Apoplast route

A pathway for water movement through the cell walls and intercellular spaces of plants.

Symplast route

A pathway for water and nutrients that involves transport through the cytoplasm of cells.

Transmembrane route

Transport pathway that crosses both the cell membrane and cell walls of lower plant cells.

Guard cells

Modified epidermal cells that control the opening and closing of stomata.

Turgid

When a plant cell is swollen due to water uptake, maintaining pressure against the cell wall.

Flaccid

When a plant cell loses water, leading to diminished turgor pressure.

Plasmolyzed

Condition of plant cells when they lose water and the membrane pulls away from the cell wall.

Photosynthesis

The process by which plants convert light energy, usually from the sun, into chemical energy in the form of glucose.

Translocation

The movement of organic materials, such as sugars, through the phloem in vascular plants.

Cytoplasmic streaming

The movement of the fluid cytosol within plant cells, aiding in the transport of nutrients.

Pressure flow mechanism

A method of translocating phloem sap driven by pressure differences in the sieve tubes.

Companion cells

Specialized cells in the phloem that assist in the transport of sugars.

Sieve-tube elements

Cells that make up the phloem and facilitate the transport of sap.

Sieve plates

Perforated areas at the ends of sieve-tube elements allowing the flow of phloem sap.

Cohesion

The attraction between molecules of the same substance, e.g., water molecules sticking together.

Adhesion

The attraction between different types of molecules, e.g., water molecules adhering to xylem walls.

Bulk flow

The mass movement of fluid in response to pressure differences, significant in xylem and phloem transport.

Guttation

The exudation of water droplets from plant leaves due to root pressure.

Transpirational pull

The negative pressure created by transpiration that pulls water up through the xylem.

Circadian rhythms

Biological processes that display an endogenous, entrainable oscillation of about 24 hours.

Abscisic acid

A plant hormone that regulates various functions, including stomatal closure during stress.