Chapter 10 - Plant Phys

Translocation

Movement of nutrients through phloem.

Pressure-Flow Model

Explains bulk flow of solutes in phloem.

Source

Origin of phloem transport, e.g., leaves.

Sink

Destination of phloem transport, e.g., fruits.

Phloem Loading

Process of sugar entering phloem.

Phloem Unloading

Process of sugar exiting phloem.

Sieve Tube Elements

Thin-walled cells forming phloem tubes.

Companion Cells

Support sieve tube elements metabolically.

Girdling

Removing bark to study phloem function.

Photosynthate

Products of photosynthesis transported by phloem.

Sucrose

Primary sugar transported in phloem.

P-Protein Bodies

Block leaks in sieve plates.

Sieve Plates

Connect sieve tube elements, facilitate flow.

Callose

Carbohydrate sealing off sieve elements.

Mass Transfer Rates

Flux of nutrients in phloem, measured in µg.

Osmometer Model

Demonstrates pressure gradients in phloem transport.

Bidirectional Flow

Flow of nutrients in both directions in phloem.

Symplastic Pathway

Transport via plasmodesmata between cells.

Apoplastic Pathway

Transport through cell walls and membranes.

Sucrose-H+ Symporter

Transporter using H+ gradient for sucrose loading.

Phloem Sap

Liquid containing sugars and nutrients in phloem.

Translocation Rates

Average velocity of nutrient flow in phloem.

Hydrostatic Pressure Gradient

Pressure difference driving phloem flow.

Photosynthate Transport History

Studied by Malphighi and Hale in 17th century.

Xylem Functionality

Xylem remains functional after girdling.

Phloem Contents

Includes water, sugars, proteins, and hormones.

Phloem and Aphids

Aphids used to study phloem sap flow.

Reducing Sugars

Glucose and fructose, not typically transported.

Ureides

Nitrogen compounds mainly from nitrogen-fixing plants.

Transport Mechanisms

Include diffusion, cytoplasmic streaming, and pumps.

Loading Conditions

Solute loading lowers water potential in phloem.

Unloading Conditions

Solute unloading increases water potential in sinks.

Short-Distance Transport

Transport from photosynthate-producing cells to phloem.

Long-Distance Transport

Transport from phloem to distant sink cells.

Turgor Pressure

Pressure within sieve elements aiding transport.

Photosynthate-Producing Cells

Cells where photosynthesis occurs, loading phloem.

Phloem Parenchyma

Supportive tissue associated with phloem.

Nucleotide Phosphates

Energy carriers found in phloem.

Sieve Element-Sieve Element Connection

Plasmodesmata connect adjacent sieve tube elements.

Metabolic Functions

Companion cells perform functions for sieve elements.

Phloem Transport Studies

Research on nutrient flow in plants.

Transport Factors

Metabolic processes affect phloem loading/unloading.

Sugar Alcohols

Includes mannitol and sorbitol in phloem.

Plant Hormones

Chemical signals transported via phloem.

Inorganic Ions

Essential nutrients like K+, Mg2+, PO43- in phloem.