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will always be a water potential in the soil compared to the plant because water is constantly being lost through the leaves in transpiration. I: is this control of water loss by the stomata ‘opening and closing which allows plants to carefully control its uptake of water soluble ions needed far metaholic processes such as making amino acids. Water moves down its concentration gradient into root hair cells then travels through the root cortex and the endodermis before reaching the xylem. Water can get into xylem vessels by two routes - the symplast pathway and the apoplast pathway. If water travels via the symplast pathway then it travels from cell to cell through the cytoplasm. Neighbouring cells are connected by small channels in the cell walls called plasmodesmata. However, if water is travelling via the apoplast pathway then it passes from cell to cell through the cell walls. Plant cell walls are very absorbent and water can travel through them easily, making this the main pathway that water uscs to move fom the roots ta the xylem, It also means the water travels through the semipermeable membrane, The selective nature of this membrane allows the cell to carefully control the amount of water and solute moving in and out of cells due to its fluid model. This means that the cell can insert ar remove protein channels and aquaporins depending on its needs. This controlled movement of water from the roots and around the plant is important because water is an important metabolite in photosynthesis as well as helping cells remain turgid and give structural support . Photosynthesis allows the plant to generate a large amount of glucose needed for respiration, Respiration releases ALP which can be used in many ways. For example the active transport of H+ ions into the intermembrane space in the mass [low hypothesis of sucrose transport in a plant, Translocation is the movement of dissolved substances, such as sucrose and amino acids, from parts of the plant where the substances are made to other paris of the plant where they're needed. Translocation takes plave in the phloem - transport vessels made up of two types of cell, sieve tube clements and companion cells, The parts of the plant which make these substances are referred to as sources (e.g. the leaves) and the parts of the plant which store or use the substances are called sinks (e.g bulbs and roots). When sucrose reaches a sink, it is converted into starch for carbohydrate slorage. This maintains « concentration gradient belween the source nd the sink, so that more sucrose moves into the source. Translocation is an active process, so if respiration is reduced or inhibited (e.g. using a respiratory toxin), translocation will be impaired and the plant can control its rate of translocation with its rate of AI'P production by respiration. Firstly, companion cell actively transports hydrogen ions inta the cell membrane space. This is important because il creates # hydrogen ion gradient between the surrounding cells and the companion cell. This means that hydrogen ions move back into the companion cell down their concentration gradient through a co-transporter protein taking with it a sucrose molecule which is transported against ils concentration gradient. Sucrose moves from, companion cells into sieve tube clements by active transport which reduces the water potential of the sieve tube element, Water moves into the phloem by osmosis, which 
