The Cell Cycle

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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

Electrical Signaling in the Phloem

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.

Slide 70

Resource Acquisition and Transport

CO2

O2

O2

CO2

H2O

H2O

Minerals

Slide 71

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.

Slide 73

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.