1. Transport Process

One fundamental aspect of life itself is the ability to transport specific substances to particular site.

Transport processes consume energy, and many are driven by the exergonic breaking of ATP's high-energy phosphate-bonding orbitals.

Isolation mechanisms inhibit the movement of substances.

Diffusion

osmosis

Active Transport

Movement of by which the materials move from higher concentration to areas where they are relatively low concentration

Osmosis is a passive transport process during which water moves from areas where solutes are less concentrated to areas where they are more concentrated.

Membranes are of three types: freely permeable membrane, completely impermeable membranes, differentially or selectively permeable membranes.

Water molecules, even though highly polar, pass through all membranes, but their movement is more rapid if the membrane has protein channels called aquaporins.

Passive transport

The forced pumping of molecules from one side of a membrane to the other by means of molecular pumps located in the membrane.

These crystals located in a cell vacuole is a perfect example of active transport.

All cell membranes in transport process; are plasma membrane governs movement of material into and out of the cell.

active diffusion

ocmosis

Water potential

The chemical potential of water; a measure of the ability of a substance to absorb or release water relative to another substance. It is pronounced as "sigh".

Components: osmotic potential, pressure potential, matric potential.

“ψ = ψπ + ψp + ψm”


Excerpt From: James D. Mauseth. “Botany.”

Ψ+=+water+potential+of+the+given+solution

Cells and water movement

cells and water movement

Short-Distance intercellular transport

Guard cells

Motor cells

Transfer Cells

guard cell

Cells that swell and shrink in plant organs capable of repeated, reversible movements, such as insect traps and petioles of leaves that undergo sleep movement.

Cells involved in rapid short-distance transfer to material; they have transfer (labyrinthine) walls.

Long-distance transport: Phloem

The exact mechanism by which water and nutrients are moved through phloem is not known, most evidence supports the pressure-flow hypothesis.

Phloem-as-a-long-distance-transport-system-and-a-habitat-for-prokaryotic-pathogens-and

Long-distance Transport: Xylem

“Hypothesis that as water is pulled upward by transpiration, its molecules cohere sufficiently to withstand the tension.”


Excerpt From: James D. Mauseth. “Botany.” Apple Books.

Water movement through xylem and plants are through cohesion-tension hypothesis.

Properties of water

Water transport through xylem

Control of water thransport by guard cells

late wood