vascular strengthens tubes and supports plants?
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The turgid pressure of the water in the vascular tissues pushes against the cell wall, makeing the plant more rigid
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Materials, dissolved (or semi-dissolved?) in water, are moved up and down the plant through the xylem and phloem, such as the previous posts say.  An additional factor to think about is that materials and water also move about because of differences in pressure within the vessels of the plant. At the leaf surface, heat and wind are drying the water that is present.  As this water "dries out" of the plant through the stoma, it creates a vacuum within the vessel it was in.  This, in turn, pulls water up through the plant to replace itself (physics-search for pressure, STP). This whole process is called Transpiration.  Adhesion, thus capillary action, would not be sufficient enough a force to distribute water to the highest part of the plant.
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Nitrogen is important to plant growth.
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Water travels through a network of 'veins' through out the plant. The cells are re-hydrated which causes them to expand like a balloon. Once the cells are all filled to capacity, they rest on each other. The cell membranes contain cellulose that helps them stand erect when fully hydrated.
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Blood flow in the area. Like watering flowers, don't water and they die.
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The xylem transports sap from the root up the plant. Xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well. This transport is not powered by energy spent by the tracheary elements themselves, which are dead at maturity and no longer have living contents. Two phenomena cause xylem sap to flow:\n\nTranspirational pull: the most important cause of xylem sap flow, is caused by the evaporation of water from the surface mesophyll cells to the atmosphere. This transpiration causes millions of minute menisci to form in the cell wall of the mesophyll. The resulting surface tension causes a negative pressure in the xylem that pulls the water from the roots and soil. \nRoot pressure: If the water potential of the root cells (usually due to high concentrations of solute) is more negative than the soil, water can move by osmosis into the root. This may cause a positive pressure that will force sap up the xylem towards the leaves. In extreme circumstances the sap will be forced from the leaf through a hydathode in a phenomenon known as guttation. Root pressure is most common in the morning before the stomata open and cause transpiration to begin. Different plant species can have different root pressures even in a similar environment; examples include up to 145 kPa in Vitis riparia but around zero in Celastrus orbiculatus\n\n--> http://en.wikipedia.org/wiki/Xylem\n\n\nPhloem tissue consists of less specialised and nucleate parenchyma cells, sieve-tube cells, and companion cells (in addition albuminous cells, fibers and sclereids). The sieve-tube cells lack a nucleus, have very few vacuoles, but contain other organelles such as ribosomes. The endoplasmic reticulum is concentrated at the lateral walls. Sieve-tube members are joined end to end to form a tube that conducts food materials throughout the plant. The end walls of these cells have many small pores and are called sieve plates and have enlarged plasmodesmata.\n\nThe survival of sieve-tube members depends on a close association with the companion cells. All of the cellular functions of a sieve-tube element are carried out by the (much smaller) companion cell; a typical plant cell, except the companion cell usually has a larger number of ribosomes and mitochondria. This is because the companion cell is more metabollically active than a 'typical' plant cell. The cytoplasm of a companion cell is connected to the sieve-tube element by plasmodesmata.\n\n\n[edit] Function\nUnlike xylem (which is composed primarily of dead cells), the phloem is composed of still-living cells that transport sap. The sap is a water-based solution, but rich in sugars made by the photosynthetic areas. These sugars are transported to non-photosynthetic parts of the plant, such as the roots, or into storage structures, such as tubers or bulbs.\n\n--> http://en.wikipedia.org/wiki/Phloem
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vacuoles tend to be very large and are extremely important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth. Many plant cells have a large, single central vacuole that typically takes up most of the room in the cell (80 percent or more). Vacuoles in animal cells, however, tend to be much smaller, and are more commonly used to temporarily store materials or to transport substances.\n\nBecause the central vacuole is highly selective in transporting materials through its membrane, the chemical palette of the vacuole solution (termed the cell sap) differs markedly from that of the surrounding cytoplasm. For instance, some vacuoles contain pigments that give certain flowers their characteristic colors. The central vacuole also contains plant wastes that taste bitter to insects and animals, while developing seed cells use the central vacuole as a repository for protein storage.\n\nAmong its roles in plant cell function, the central vacuole stores salts, minerals, nutrients, proteins, pigments, helps in plant growth, and plays an important structural role for the plant. Under optimal conditions, the vacuoles are filled with water to the point that they exert a significant pressure against the cell wall. This helps maintain the structural integrity of the plant, along with the support from the cell wall, and enables the plant cell to grow much larger without having to synthesize new cytoplasm. In most cases, the plant cytoplasm is confined to a thin layer positioned between the plasma membrane and the tonoplast, yielding a large ratio of membrane surface to cytoplasm.\n\nThere are more important functions of central vacuole but i guess the functions above are enough for you to understand its role.\n\n:)
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Xylem in the stem, as xylem is responsible for transport of water
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The presence or absence of vascular tissues is used to clarify plants.\n\nIt is because of that vascular tissue that plants are capable of growing to different sizes and heights.\n\nFor example - mosses and lichens have little to no vascular tissue. This is why they are relatively small, and located only near damp places like swamps, bogs, or near the sea coast. Trees, by comparison, not only have cascular tissues, but they have 2 kinds of it! One type of xylem and phloem (the vascular tissues) become the parts that make up the bark, while another type of each, make up the wood of the tree. Basically any timber you buy from the lumber yard, is nothing but primary xylem and phloem.
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It's a tissue that grows, and it makes the plant bigger.
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mainly, the heart pumps blood forward, but can be aided by the action of the muscles--they help keep blood and lymph flowing.  Additonailly, the veins have one way valves so that once the blood goes through a valve, it can't go backwards while the heart is relaxing.
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Phloem and Xylem.\nWeb site below is good :)
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Increase in size for better dispersal of spores \nSporangia are more elevated above ground for better dispersal through air. \nDifferentiation of vascular tissue for more efficient transport of food and water through the plant body. \nEvolution of roots, stems and leaves. \nDifferentiation of xylem and phloem tissue \nWith increase in size tissues functioning in structural support also evolved. \nCells, vessel elements and sclerenchyma tissue which has Tracheid lignin evolved in secondary wall
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Not all plants have roots. The ones that do are the vascular plants which need to take in nutrients passively by means of capillary action and concentration gradients. The plants need their roots to reach down far enough into the vadose zone to get water during times of the year when there isn't much rain and the water table is dropping.\n\nAs already mentioned, roots also stabilize the plant to allow it to grow tall and get sunlight. In many places, competition for sunlight is intense so plants have to grow tall and hold themselves up. Thus, the need for roots.
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Heart, arteries, veins.
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The Circulatory system?
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Try eating plenty of garlic either in the food you eat or in capsule form ,garlic cleans fat deposits out of your arteries and veins leaving more room for the blood to flow.