Plant Nutrition and Transport Mechanisms in Vascular Plants

Xylem

Vascular tissue transporting water and minerals upward.

Phloem

Vascular tissue transporting sugars from sources to sinks.

Stomata

Pores regulating gas exchange and water loss.

Root Pressure

Pressure pushing water upward in roots.

Transpirational Pull

Negative pressure created by water evaporation.

Transpiration

Water loss from leaves via stomata.

Translocation

Movement of nutrients through phloem.

Apoplastic Transport

Movement through cell walls and intercellular spaces.

Symplastic Transport

Movement through cytoplasm via plasmodesmata.

Transmembrane Transport

Movement across cell membranes.

Bulk Flow

Mass movement of water and nutrients.

Negative Pressure Flow

Water movement due to negative pressure.

Positive Pressure Flow

Nutrient movement due to positive pressure.

Water Potential

Potential energy of water in a system.

Solute Potential

Effect of solute concentration on water potential.

Turgor Pressure

Pressure of cell contents against cell wall.

Pressure Gradients

Differences in pressure driving material transport.

Source

Location where nutrients are produced or stored.

Sink

Location where nutrients are utilized or stored.

Photosynthesis

Process converting light energy into chemical energy.

Adaptations

Traits enhancing survival and resource acquisition.

Aspen Leaves

Example of adaptation minimizing water loss.

Oxygen (O2)

Gas required for aerobic respiration in plants.

Carbon Dioxide (CO2)

Gas used in photosynthesis by plants.

Pressure potential

Physical pressure on a solution, can vary.

Turgid

Cell maximally filled with water, exerts pressure.

Root hairs

Increase surface area for water and mineral absorption.

Casparian strip

Waxy barrier controlling substance entry into xylem.

Apoplastic route

Pathway for water movement through cell walls.

Symplastic route

Pathway for water movement through cytoplasm.

Guard cells

Control stoma diameter by changing shape.

Cohesion-tension hypothesis

Explains water movement in plants via transpiration.

Evapotranspiration

Combined loss of water through evaporation and transpiration.

Wilting

Occurs when water uptake cannot replace lost water.

Xylem sap

Fluid transporting water and nutrients from roots.

Epidermis

Outer layer of roots, permeable to water.

Endodermis

Inner layer of root cortex, regulates water entry.

Vascular cylinder

Central part of root containing xylem and phloem.

Heartwood

Non-conducting central part of a tree's trunk.

Adhesion

Tension of water molecules to xylem walls.

Cohesion

Water molecules stick together via hydrogen bonds.

Stoma

Microscopic pores for gas exchange in leaves.

Mesophyll Cells

Leaf cells where photosynthesis occurs.

Photoautotrophs

Organisms that produce their own food using light.

Chloroplasts

Organelles where photosynthesis takes place.

Light Reactions

Convert solar energy to chemical energy.

Calvin Cycle

Light-independent reactions producing glucose from CO2.

NADPH

Electron carrier produced in light reactions.

ATP

Energy currency generated during light reactions.

Carbon Fixation

Incorporation of CO2 into organic molecules.

Grana

Stacks of thylakoids in chloroplasts.

Thylakoids

Membrane sacs where light reactions occur.

Stroma

Dense fluid within chloroplasts.

Chlorophyll

Green pigment that captures light energy.

Water Uptake

Process of water absorption by roots.

Water Potential Gradient

Difference in water potential driving water movement.

Photosynthesis Equation

6 CO2 + 6 H2O + Light → C6H12O6 + 6 O2.

Photosystems

Complexes of chlorophyll and proteins for light absorption.

Photosystem II

First photosystem in the light reaction sequence.

Photosystem I

Second photosystem in the light reaction sequence.

Electron Transport Chain

Series of proteins transferring electrons in thylakoids.

Proton Gradient

Difference in proton concentration across a membrane.

Chemiosmosis

Process of ATP production using a proton gradient.

Oxygen By-Product

O2 released during light-dependent reactions.

Glyceraldehyde 3-Phosphate (G3P)

Three-carbon sugar produced in the Calvin cycle.

Reduction Stage

Second stage; PGA converted to G3P using ATP/NADPH.

Regeneration Stage

Final stage; RuBP is regenerated for the cycle.

RuBP

Five-carbon sugar that accepts CO2 in Calvin cycle.

Rubisco

Enzyme catalyzing the first step of carbon fixation.

Sugar Source

Organ producing excess sugar, e.g., mature leaves.

Sugar Sink

Organ consuming or storing sugar, e.g., roots.

Pressure Flow Mechanism

Bulk flow of phloem sap driven by pressure differences.