Plant Transport & Osmosis
Transport in Flowering Plants
Xylem
Transports water and minerals from roots to stems and leaves.
It is composed of specialized cells called tracheids and vessel elements.
Water moves through the xylem because of transpiration and cohesion-adhesion forces.
Phloem
Transports sugars produced during photosynthesis from leaves to other parts of the plant.
Consists of sieve tube elements and companion cells.
Sugars move through the phloem via a pressure flow mechanism driven by osmotic pressure gradients.
Autotrophic Nature of Plants
Autotrophy
The ability of plants to produce their food through photosynthesis.
Chloroplasts in plant cells contain chlorophyll, which captures sunlight to synthesize sugars from carbon dioxide and water.
Oxygen is released as a byproduct of photosynthesis.
Movement Through Cell Membranes
Osmosis
Movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. It also helps plant roots uptake water from the soil.
Diffusion
Passive movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached. It is also important to move gases like oxygen and carbon dioxide in and out of plant cells.
Active Transport
Requires energy (ATP) to move molecules or ions against their concentration gradient, from an area of lower concentration to an area of higher concentration. But it also helps to uptake mineral ions by plant roots from the soil against their concentration gradient.
Other Related Terms
Turgor Pressure
Pressure is exerted by the fluid (usually water) inside the central vacuole against the cell wall in plant cells.
Provides mechanical support and rigidity to plant cells and tissues.
Plasmolysis
Shrinking of the cytoplasm away from the cell wall because of water loss in hypertonic conditions.
Occurs when plant cells lose water through osmosis, leading to wilting.
Guttation
The process by which water is released from the tips or edges of leaves through specialized structures called hydathodes.
Occurs when root pressure forces water up into the plant, usually during the night when transpiration is low.
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