Why plant distributes sugar in the form of sucrose?

In summary, plants distribute sugar in the form of sucrose in the phloem because it is the only form of sugar that can be transported through the phloem. Other forms of sugar, like glucose, do not have a transport mechanism. Starch is a more efficient way for plants to store energy because it is not soluble and does not affect osmotic pressure. Similarly, glycogen works in the same way for animals, keeping glucose concentrations low in tissues and easily converted back to simple sugars.
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Hilmy atha
13
3
Few months back, in the final rounds of biology olympiad for Highschool students, i was asked, "Plants distributes sugar in the phloem as sucrose molecules, why did plant do this, and is there any advantages? Why not other form of sugar like glucose?"Can anyone help me? :3
Also i was wondering why animals store energy in form of fat or glycogen while plants store them in form of amylum
 
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There are two type of sucrose translocation in the phloem.

In the first mechanism, sucrose enters the phloem by attaching to sucrose transporter proteins embedded in the plasma membranes of the sieve elements and companions cells. In the second mechanism, sucrose enters the companion cells of the phloem through small plasmodesmata (openings in the cell wall), and is converted to larger sugars. Ex., raffinose, stachyose. So, glucose cannot move from the leaf down through the phloem because there is no transport mechanism.

So an answer is: the mechanisms of transport only "work" for sucrose.
http://www.biologyreference.com/Ta-Va/Translocation.htmlStarch is a synonym for amylum, and more often used. Starch is stored as small inclusions - granules or grains - because it is not soluble. That means cells can contain lots of starch without altering osmotic pressure, like glucose or sucrose would do. Concentrations of simple sugars would simply increase in storage tissue like roots, to the point where the cytoplasm would have a very high concentration. Net movement of additional simple carbs into the cell would become difficult - or close to impossible. If simple carbs come into the storage cell and then are immediately converted to starch, they no longer negatively affect the movement. So, there is no problem moving new simple carbs into that same cell.

Starch is a collective term - there are multiple type of starch molecules. Some types absorb water, some like amylopectin do not absorb water.

Glycogen works similarly to starch - it keeps glucose concentrations low in animal tissues where it is stored near the liver. And, like starch, converting glycogen back to simple sugars is easy to do and efficient (in biochemical terms this is called hydrolysis).
 
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1. Why do plants distribute sugar in the form of sucrose?

Sucrose is the most common form of sugar found in plants and is used as a source of energy for the plant's growth and development. It is also easily transported throughout the plant and can be stored for later use.

2. How is sucrose distributed in plants?

Sucrose is produced in the leaves through photosynthesis and is then transported through the plant's vascular system to other parts of the plant, such as the roots, stems, and fruits. It can also be stored in specialized storage organs, such as tubers and bulbs.

3. Are there other forms of sugar found in plants besides sucrose?

Yes, there are other forms of sugar found in plants, such as glucose, fructose, and maltose. These sugars are often used for specific purposes, such as energy storage or structural support.

4. Can plants control the distribution of sucrose?

Plants have specialized cells and tissues, such as phloem, that are responsible for the distribution of sucrose throughout the plant. These cells can control the movement of sucrose to different parts of the plant based on the plant's needs.

5. What happens to excess sucrose in plants?

If a plant produces more sucrose than it needs for immediate use, it can be stored in storage organs or converted into other forms of sugar for long-term storage. Excess sucrose can also be used by the plant to attract pollinators or to defend against herbivores.

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