The symplast is a living tissue and is responsible for dynamic changes in plant transport processes.
Plasmodesmata can change in permeability in response to turgor pressure, cytoplasmic calcium levels, or cytoplasmic pH.
Plant viruses can cause plasmodesmata to dilate
Mutations that change communication within the symplast can lead to changes in development.
Slide 67
Question: Do alterations in symplastic communication affect plant development?
EXPERIMENT Results
Base of cotyledon
Root tip
50 µm
50 µm
Wild-type embryo
Mutant embryo
Slide 68
Question: Do alterations in symplastic communication affect plant development?
Experiment RESULTS
50 µm
50 µm
Wild-type seedling root tip
Mutant seedling root tip
Slide 69
The phloem allows for rapid electrical communication between widely separated organs.
Phloem is a “superhighway” for systemic transport of macromolecules and viruses.
Systemic communication helps integrate functions of the whole plant.
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Resource Acquisition and Transport
CO2
O2
O2
CO2
H2O
H2O
Minerals
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Explain: Root Hairs Short Distance Transport of Water to Stele: Xylem …
Slide 72
You should now be able to:
Describe how proton pumps function in transport of materials across membranes.
Define the following terms: osmosis, water potential, flaccid, turgor pressure, turgid.
Explain how aquaporins affect the rate of water transport across membranes.
Describe three routes available for short-distance transport in plants.
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Relate structure to function in sieve-tube cells, vessel cells, and tracheid cells.
Explain how the endodermis functions as a selective barrier between the root cortex and vascular cylinder.
Define and explain guttation.
Explain this statement: “The ascent of xylem sap is ultimately solar powered.”
Slide 74
Describe the role of stomata and discuss factors that might affect their density and behavior.
Trace the path of phloem sap from sugar source to sugar sink; describe sugar loading and unloading.