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Some experiments indicate that bidirectional movement may occur in a single sieve tube, whereas others do not. The bidirectional movement of solutes in the translocation process and the fact that translocation is heavily affected by changes in environmental conditions like temperature and metabolic inhibitors are two defects of the hypothesis.
Sugars are actively loaded into the phloem and moved by a positive pressure flow created by solute concentrations and turgor pressure between xylem and phloem vessel elements (specialized plant cells). This movement of sugars is referred to as translocation. When sugars arrive at the sink they are unloaded for storage or broken down/metabolized ...
Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients. When water uptake by the roots is less than the water lost to the atmosphere by evaporation, plants close small pores called stomata to decrease water loss, which slows down nutrient uptake and decreases CO 2 absorption from the ...
3- Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata. In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem to the leaves where it evaporates into the air/ apoplast ...
Active transport enables these cells to take up salts from this dilute solution against the direction of the concentration gradient. For example, chloride (Cl −) and nitrate (NO 3 −) ions exist in the cytosol of plant cells, and need to be transported into the vacuole. While the vacuole has channels for these ions, transportation of them is ...
In smaller cells, the diffusion of molecules is more rapid, but diffusion slows as the size of the cell increases, so larger cells may need cytoplasmic streaming for efficient function. [ 1 ] The green alga genus Chara possesses some very large cells, up to 10 cm in length, [ 2 ] and cytoplasmic streaming has been studied in these large cells.
Unlike the static nature typically depicted in textbooks, the plant cell nucleus is a highly dynamic structure, constantly moving around cells via actin networks and myosins. [1] The nucleus undergoes a characteristic program during cell division to guide asymmetric cell division, [ 2 ] but there are several stimuli that have been demonstrated ...
The normal lifespan of plant cells is one to three years. Stems have cells called meristems that annually generate new living tissue. Photosynthesis. Stems have two pipe-like tissues called xylem and phloem. The xylem tissue arises from the cell facing inside and transports water by the action of transpiration pull, capillary action, and root ...