xylem part 2

Adhesion and cohesion together produce the phenomenon of

Capillary action

Capillary action

The movement of liquid up a narrow space against gravity, driven by the combined forces of cohesion and adhesion. This phenomenon allows liquid to rise and thin tubes, plant xylophone, paper, towel, towels, sponges.

Why are surfactant added to water?

They reduce waters surface tension, allowing it to penetrate and spread more evenly through the soil, reaching the roots more effectively

Soil water potential

Solute potential + pressure potential + gravity potential

Is gravity potential a major force in soil water potential?

No

What is the major force in soil water potential?

Pressure potential

Water and soil moves by

Bulk flow

Rate of water flow depends on

1. Soil hydraulic conductivity

2. Pressure potential

Soil hydraulic conductivity

Impacted by the soils particle shapes. Sandy soil – large Particles

Clay soil – small particles

What do soils with large particles do

Have higher hydraulic conductivity because they contain larger and more connected pore spaces that allow water to flow more freely. larger surface area to volume ratio and soil is more permeable, allowing for faster water movement

water is absorbed through

Root hairs

Root Hairs

Outgrowths of root epidermal cells

Increase surface area

Why is suberin used in the roots?

Plants want to drive its roots deeper into soil so plants use suberin along the plant so only root tips are permeable to water

vascular cambium

Contributes to a trees secondary growth by acting as a lateral meristem that produces new layers of secondary xylem and secondary phloem through continuous cell division. the cambium divides adding secondary xylem cells inwardly towards the pith and secondary phloem cells outwardly towards the bark, increasing the trees girth and providing structural strength, and a robust transport system

Apoplast

continuous system of cell walls, intracellular air spaces, and lumens of nonliving cells (xylem)

Symplast

Entire network of cell cytoplasm interconnected by plasmodesmata

Trans membrane pathway

Water crossing plasma membranes to move from one cell to the next

how can water be expelled from a plant stem or leaf?

Transpiration or guttation

Transpiration

Water vapour is released from leaves through tiny pores called stomata.

What happens when transpiration is low?

Solute accumulation still occurs leading to a positive pressure in the xylem. This leads to a higher solute potential, encouraging water to move into the plant from the roots and create turgor pressure, causing stomata to open for gas exchange

Guttation

Water being pushed through hydathodes on leaf margins