This water creates turgor pressure in the sieve elements, a plant. within phloem tissue, glucose and other sugars are always transported from a sugar source , a part of the plant where sugar is stored or produced, to a sugar sink , a part of the plant where sugar is used. There are various types of sugar derived from different sources. The movement of dissolved sugars from the leaves to the rest of the plant is called translocation. Storage organs such as roots can also be sugar sources if they are releasing sugars, such as after the winter. Palisade layer Phloem Stomata Xylem [Turn over] Phloem, the Carbohydrate Transport. to sinks, is called pressure flow. Lateral sieve areas connect the sieve-tube elements to the companion cells. C. corn plants D. mushrooms 2. Content of Biology 1520 Introduction to Organismal Biology, Content of Biology 1510 Biological Principles, Multicellularity, Development, and Reproduction, Animal Reproductive Structures and Functions, Animal Development I: Fertilization & Cleavage, Animal Development II: Gastrulation & Organogenesis, Plant Development I: Tissue differentiation and function, Plant Development II: Primary and Secondary Growth, Principles of Chemical Signaling and Communication by Microbes, Nutrition: What Plants and Animals Need to Survive, Oxygen & Carbon Dioxide: Gas Exchange and Transport in Animals, Ion and Water Regulation, Plus Nitrogen Excretion, in Animals, The Mammalian Kidney: How Nephrons Perform Osmoregulation, Plant and Animal Responses to the Environment, Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License, Differentiate between sugar sources and sugar sinks in plant tissues, Explain the pressure flow model for sugar translocation in phloem tissue, Describe the roles of proton pumps, co-transporters, and facilitated diffusion in the pressure flow model, Recognize how different sugar concentrations at sources and different types of sinks affect the transport pathway used for loading or unloading sugars, Compare and contrast the mechanisms of fluid transport in xylem and phloem. The sugar and other organic molecules are transported through the plant by means of a special layer of tissue called phloem . At the end of the growing season, the plant will drop leaves and no longer have actively photosynthesizing tissues. Plant Form and Function. roots to leaves leaves to roots flowers to stem none of the above 4._____ absorbed by the roots is transmitted through the plant in the xylem. Water follows the sugar molecules into the sieve elements Sinks are areas in need of nutrients, such as growing tissues. Translocation stops if the phloem tissue is killed, Translocation proceeds in both directions simultaneously (but not within the same tube), Translocation is inhibited by compounds that stop production of ATP in the sugar source, Xylem: transpiration (evaporation) from leaves, combined with cohesion and tension of water in the vessel elements and tracheids (passive; no energy required), Phloem: Active transport of sucrose from source cells into phloem sieve tube elements (energy required), Xylem: Non-living vessel elements and tracheids, Phloem: Living sieve tube elements (supported by companion cells), Xylem: Negative due to pull from the top (transpiration, tension), Phloem: Positive due to push from source (Ψp increases due to influx of water which increases turgor pressure at source). These are transport by either the xylem of phloem, which collectively are described as the vascular bundle. Early at the start of the next growing season, a plant must resume growth after dormancy (winter or dry season). Use up and down arrows to review and enter to select. The high turgor pressure drives movement of phloem sap by “bulk flow” from source to sink, where the sugars are rapidly removed from the phloem at the sink. Phloem transports sucrose and amino acids up and down the plant. The main substances transported on mass in plants are water and organic substance. 33. These sugars are transported through the plant via the phloem in a process called translocation. The process of moving sugars through the phloem is called translocation. Most of the carbohydrates manufactured in plant leaves and other green parts are moved through the phloem to other parts of the plant. (a) €€€€Use the correct answer from the box to complete each sentence. Many plants lose leaves and stop photosynthesizing over the winter. low water pressure, called sinks. sugar molecules are moved into the sieve elements (phloem cells) through Within the For example, the highest leaves will send sugars upward to the growing shoot tip, whereas lower leaves will direct sugars downward to the roots. Sugars produced in sources, such as leaves, need to be delivered to growing parts of the plant via the phloem in a process called translocation, or movement of sugar. Plants convert light energy from the sun into biochemical energy that is used to synthesize the sugars and amino acids through the complex photosynthetic process. A process called _____ drives the movement of dissolved sugars from sources to sinks. Phloem is composed of living cells that transport a water solution of sugars that we commonly call sap. vascular tissue responsible for transporting organic nutrients around the water pressure, called sources, to regions of low osmotic concentration and Xylem transports water and minerals. movement of substances across cell membranes requires energy expenditure on the Plants were provided with only radioactively labelled carbon dioxide. Sugar is the generalised name for a class of sweet-flavored substances used as food. Phloem moves sugars from the places they are made (the leaves) to various non-photosynthetic parts of the plant. 2.Dermal tissue covers the outer surface of _____, or soft-stemmed, plants. This creates a proton gradient. After feeding, the mouthpiece of an aphid contains a high concentration of dissolved sugars. 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