was just looking through some unit 2....I have completely forgotten (if i new it in the first place) the 'translocation of organic solute' in plants.....iso confused ...textbook doesnt make n e sense 2 me *starts to panic*..n e 1 willing to enlighten me?
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stuckstuck>< unit 2 watch
- Thread Starter
- 20-06-2005 13:04
- 20-06-2005 13:23
The transport of an organic solute in plants. That would be via the phloem vessels made up of seive tubes and companion cells. The opposite is xylem which transports water and inorganic ions.
To be honest i don't really understand what you are asking me. Could you be more specific in your question and i'll try to help.
- Thread Starter
- 20-06-2005 14:03
yes, will do ^^
say if the question asks:
'describe how the products of photosynthesis are transported in the plant'
for 5 marks? (taken fromjan 03 unit 5 paper)
- 20-06-2005 14:30
Ok. So first you need to define the products of photosynthesis...so your looking at carbohydrates and O2 as waste product (O2 is still a product so you should get marks)- 02 diffuses down its concentration gradient out throughthe stomatal openings.
The carbohydrates produced travel through phloem vessels by mass flow. The contents is termed "sap" and can move up down , left and right but only in one diretcion per tube at one time.
Phloem vessels are made well for this kind of transport as they are living cells (unlike xylem).
You would also get translocation in there whcih basically describes the mechanuism which drives the process. Basically in water transport no ATP is needed to make the water move upwards , its a natural process in response to concentration gradients. Hoever in phloem transport it is an active process as a pressure difference has to be generate at the top and bottom of the "tube" to produced a sucking action. This pressure is created by the active loading of sucrose into the seieve elements (revise structure) at the place were it needs to be transported. As sucrose is loaded the water potential of the sap is lowered and thus sucrose moves down its potential gradient. Hydrostatic pressure will cause this movement.
Sorry the answer is so jumbled. If your textbook is unclear try breaking it down into smaller chunks instead of reading the whole thing.