Compare and contrast xylem and phloem.?
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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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just fyi i would have made this a biology question but anyway, chlorophyll a and b would be present in both leaves its not one or the other.  this sounds like homework don't you think that you should be figuring this out on your own.  i'll give you a couple hints.  you need a solute so that you can separate the pigments.  the pigments  will travel farther if the are less soluble.  Anyway thats all i'm giving you good luck.
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Vascular tissue is a complex tissue found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue: the vascular cambium and the cork cambium. All the vascular tissues within a particular plant together constitute the vascular tissue system of that plant.
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I will split your question in to two parts viz. 1) Photosynthesis and 2) Stomata; so that you can easily understand it.\n 1) PHOTOSYNTHESIS-: for this function entire middle portion of a leaf contributes, it is called MESOPHYLL in botanical language.(Meso = middle or in between; Phyll = refers to leaf). It is located in between the upper and the lower skin or the epidermis of a leaf (Plural epidermes).\n In most of the leaves the MESOPHYLL is again distinguished it to Upper PALISDE tissue and the Lower SPONGY LAYER.\n Both of them are full of chloroplast and do the function of photosynthesis; but there is a difference.\n The palisade cells are located near the upper epidermis,they are elongated,test tube like in appearence and are placed at right angle to the upper epidermis like upright test tubes.( try to see the meaning of palisade in a good dictionary, it is interesting.). These palisade cells are very closely packed with very little space in between and each of them is literally packed with chloroplasts. That is why a leaf appears greener on its upper surface.Thus, they are ideally located to receive maximum sun light and do maximum photosynthesis.\n\nThe Spongy layer , on the other hand , is located near the lower epidermis of a leaf. The cells are spherical or potato shaped and with lots of intercellular spaces between them. Each cell of this layer contains (comparitively) less or far less number of chloroplasts than the palisade of the same leaf.That is why the same leaf appears pale green on its lower surface.\n This Spongy layer does the function of photosynthesis no doubt ; but it is less in quantity than that of Palisade of the same leaf. This is because it is located rather away from the light source and its main function is to help the leaf in gaseous exchange, that is why there are so many intercellular spaces.( here Photosynthesis is over)... \n\n2) STOMATA (singular stoma) -: These breathing pores are neither IN the palisade layer nor IN the spongy layer. They are a PART of the the two epidermes( upper and lower ).\n If one compares the quantity and the distribution of these stomata of one and the same leaf then they are more on the lower epidermis to help the spongy tissue in gaseous exchange during photosynthesis/respiration.\n On the upper epidermis they are far less in number to reduce or prevent exessive water loss due to transpiration.\nIn many desert plants they are either totally absent from the upper epidermis or located in sunken pits for the same reason.\nI hope you got what you sought. Bye.
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During the plant's growth period, usually during the spring, storage organs such as the roots are sugar sources, and the plant's many growing areas are sugar sinks. The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward).A high concentration of organic substance inside cells of the phloem at a source, such as a leaf, creates a diffusion gradient that draws water into the cells. Movement occurs by bulk flow; phloem sap moves from sugar sources to sugar sinks by means of turgor pressure. A sugar source is any part of the plant that is producing or releasing sugar.
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chloroplast of course!\nPHOTOSYNTHESIS!!
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'\nxylem vascular tissue makes the wood after the secondary growth then it is called 'secondary xylem'.
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When the roots absorb the water it goThe xylem takes also part in food storage, support and the conduction of minerals. Xylem and phloem together form a continuous system of vascular tissue extending throughout the plant. The principal conductive cells of the xylem are tracheary elements, of which there are two types, tracheids and wood vessels. Both are elongated cells with secondary cell walls that lack protoplasts at maturity. They are completed by the xylem fibres and parenchyma cells. Much speaks on behalf of the origin of xylem fibres and wood vessels from the tracheids. \n\nSince 1851, the isolation and depiction of lignified cells is done according to the maceration procedure of SCHULZE. Small pieces of wood are covered with a mixture of potassium perchlorate and concentrated nitric acid. The complete volume should not be larger than 1/10 of the reaction container, because a lot of gas develops very quickly at cautious heating. The surfaces of the wooden pieces are strongly attacked. The single cells can be scraped off after washing of the preparation and examined under the microscope.
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Water equalizes the pressure between the outside and the inside of the cell wall, so it doesn't become damaged.  It also is the transport medium for nutrients coming in, and waste exiting.
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enjoy!\n\n\nhttp://waynesword.palomar.edu/slime1.htm
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The conduction of water in the xylem vessels of plant that is movement of water from root to shoot. Several theories have been forwarded to explain this phenomenon but none were absolutely flawless. The principal theories propounded to explain ascent of sap are a. vital theory b. cohesion-tension theory c. root pressure theory d. CP theory (The compensating-pressure theory).\n\nInspite of researches more than hundred in this field, the phenomena is still unsolved.
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I've found the Munsell Book of Color the best reference for comparing colours:\nhttp://www.it.lut.fi/ip/research/color/database/munsell.html\nI own a book given as a reference below, but it is mostly for plant leaves and probably lacks the right colour chips for all shades of mango. But it is waaay easier to find than the Book of Color! (And actually USE.)
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Vascular refers to the transport of materials through a network.  Our vascular system transports blood.  Plants   that have a vascular system (similar to the veins and arteries we have) transport water through it.   Simple plants don't have a vascular system and rely on being small (~1 to 2 cm high) so that they don't have to transport water.
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THERE ARE FOUR DIFFERENCES!!!!!!! NOT THREE. Some people say five\n\n1) Chloroplasts\n2) Central Vacuole and tonoplast (the membrane enclosing the vacuole)\n3) Cell Wall\n4) Plasmodesmata (channels through cells walls that connect cytoplasms of adjac3ent cells.)
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For Plant cells:\n\n1)Parenchyma cells:\n--Primary walls that are rel. thin and flexible, no secondary walls\n-- perform most of the metabolic activity of the cell (photosynthesis etc)\n-- Retain the ability to divide and differentiate\n\n2)Collenchyma cells:\n-- thicker primary walls, no secondary walls\n-- help support young parts of plants\n\n3)Sclerenchyma cells:\n-- thick primary and secondary walls\n-- Can no longer elongate, so occur in parts of the plant that have stopped growing\n-- dead at maturity\n\ntwo catergories: sclereids and fibers\n\n4)Water conducting cells of the xylem\n-- tubular, elongated cells\n--dead at maturity\n\n2 categories:\na) Tracheids: long, thin\nb) Vessel elements: wider, shorter, thinner walled\n\n5) Sugar conducting cells of the phloem\n\n-- Alive at functional maturity:\n* Sieve tube members are the main components of the phloem\n* Companion cells, which facilitate loading sugars
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Answers provided so far a basically correct except they have the primary functions of xylem and phloem reversed. See links below.
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The periderm is the outer bark of a tree.The periderm is a secondary tissue that replaces epidermis in roots and stems, and which consists of phellem, phellogen, and phelloderm (it includes dead tissues). while the inner bark is called the phloem,It conducts usable food from the leaves to the cambium to nourish it or to storage areas in the wood (it includes living tissues)and consists of  of alternating wedges of sieve tube tissue and radial parenchyma, most of the former crushed by secondary growth.