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Because the plant vascular system is vital in growth and development of plant cells and the organs within the plant, the role of sieve elements in the transport of necessary carbohydrates and macromolecules is largely expanded. This can be applied to agriculture to observe the way resources are distributed to various parts of the plant.
Some plants appear not to load phloem by active transport. In these cases, a mechanism known as the polymer trap mechanism was proposed by Robert Turgeon. [5] In this model, small sugars such as sucrose move into intermediary cells through narrow plasmodesmata, where they are polymerised to raffinose and other larger oligosaccharides. As larger ...
Epilobium hirsutum seed head dispersing seeds. In spermatophyte plants, seed dispersal is the movement, spread or transport of seeds away from the parent plant. [1] Plants have limited mobility and rely upon a variety of dispersal vectors to transport their seeds, including both abiotic vectors, such as the wind, and living vectors such as birds.
Polar auxin transport (PAT) is directional and active flow of auxin molecules through the plant tissues. The flow of auxin molecules through the neighboring cells is driven by carriers (type of membrane transport protein) in the cell-to-cell fashion (from one cell to other cell and then to the next one) and the direction of the flow is determined by the localization of the carriers on the ...
However, without dedicated transport vessels, the cohesion-tension mechanism cannot transport water more than about 2 cm, severely limiting the size of the earliest plants. [33] This process demands a steady supply of water from one end, to maintain the chains; to avoid exhausting it, plants developed a waterproof cuticle .
The general mechanism for the transport cycle of ABC transporters has not been fully elucidated, but substantial structural and biochemical data has accumulated to support a model in which ATP binding and hydrolysis is coupled to conformational changes in the transporter.
Although several mechanisms have been proposed to explain how sap moves through the xylem, the cohesion-tension mechanism [1] has the most support. Although cohesion-tension has received criticism due to the apparent existence of large negative pressures in some living plants, experimental and observational data favor this mechanism. [2] [3]
The patterns of seed dispersal are determined in large part by the specific dispersal mechanism, and this has important implications for the demographic and genetic structure of plant populations, as well as migration patterns and species interactions. There are five main modes of seed dispersal: gravity, wind, ballistic, water, and by animals.