Phloem and Xylem (1 Viewer)

[Jono10]

Hey, this is probably one of the things that is most difficult for me in this topic.

I have a basic understanding of it but i still cant go into depth with it.

Im talking about the current theories about processes responsible for the movment of materials through plants in xylem and phloem tissue.

All the structures in a plant i find it hard to understand, so if there are any sites or pictures of the xylem and phloem it would help me understand. Im a visual learner in this area.

Anyhelp with anything to do with the phloem and xylem would be greatly appreciated.

If this has been posted before, just direct me to the other topic.

Thanks.

 

[katie tully]

Google transpiration and translocation

Should be heaps of diagrams out there on transpiration and translocation.

 

[danz90]

While on the topic of xylem and phloem.. I keep getting confused:

Is xylem situated on the outer side, and phloem on the inside? i.e. where they join at the cambium. That's what my bio teacher tells me..

But in some textbooks i've seen phloem on the outer side, and xylem on the inner side.

Confucious...

 

[Jono10]

That makes it even more confusing danz, whats the cambium

And katie, is translocation and transpiration the theries?

Because ive also thought source to sink was a theorie, aswell as symplastic and apoplastic loading. Which ones are the theories?

 

[katie tully]

http://en.wikipedia.org/wiki/Transpiration

The phloem is mainly concerned with the transport of soluble organic material made during photosynthesis. This is called translocation.

http://en.wikipedia.org/wiki/Phloem
http://en.wikipedia.org/wiki/Xylem
I mean, you won't get it explained to you in basic terms better than wikipedia.

Source to sink is a theory, yes. Transpiration and translocation are not theories.

 

[Jono10]

Katie, can you try explainin it

 

[katie tully]

Katie, can you try explainin it

Yeah ok but it's been 3 years since I did my HSC, give me a second to type it up.

 

[katie tully]

Phloem: Carries the sucrose and other organic nutrients to where they're needed. It is located on the outside (Phloem comes from the Greek word 'bark', so you will always remember it's on the outside). Translocation is the method used to transport the sucrose/nutrients.
Unlike the xylem:
- the phloem is composed of still-living cells
- Pressure flow hypothesis was a hypothesis proposed by Ernst Munch in 1930 that explained the mechanism of phloem translocation

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. 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)

Xylem: From the Greek word 'wood'
- The xylem is responsible for the transport of water and soluble mineral nutrients from the roots throughout the plant.
Sap in the xylem travels via ....
Transpiratoinal Pull - the evaporation of water from the surfaces of cells in the interior of the leaves.
Root Pressure - f the water potential of the root cells is more negative than the soil, usually due to high concentrations of solute, water can move by osmosis into the root. This causes a positive pressure that forces sap up the xylem towards the leaves

 

[The_highwayman]

While on the topic of xylem and phloem.. I keep getting confused:

Is xylem situated on the outer side, and phloem on the inside? i.e. where they join at the cambium. That's what my bio teacher tells me..

But in some textbooks i've seen phloem on the outer side, and xylem on the inner side.

Confucious...

the way i used to think of it was that water is more important than food so the xylem (which carries water) was more protected in the centre of the stem whilst the Ph-Ph-Phloem (which carried F-F-Food) is outside.

That's not necessarily the exact reason but that's how i remembered it.


EDIT: b10 by tully. remember 'bark' if it's easier.

 

[katie tully]

lol ph-ph-phloem.

weirdo.

 

[Jono10]

Phloem: Carries the sucrose and other organic nutrients to where they're needed. It is located on the outside (Phloem comes from the Greek word 'bark', so you will always remember it's on the outside). Translocation is the method used to transport the sucrose/nutrients.
Unlike the xylem:
- the phloem is composed of still-living cells
- Pressure flow hypothesis was a hypothesis proposed by Ernst Munch in 1930 that explained the mechanism of phloem translocation


Xylem: From the Greek word 'wood'
- The xylem is responsible for the transport of water and soluble mineral nutrients from the roots throughout the plant.
Sap in the xylem travels via ....
Transpiratoinal Pull - the evaporation of water from the surfaces of cells in the interior of the leaves.
Root Pressure - f the water potential of the root cells is more negative than the soil, usually due to high concentrations of solute, water can move by osmosis into the root. This causes a positive pressure that forces sap up the xylem towards the leaves

thanks a bunch katie....legend

 

[The_highwayman]

lol ph-ph-phloem.

weirdo.

phonics are great for my learningz

 

[Jono10]

heyy, ive been doing more reading on this

Is this right:

Plants get their nutrients through photosynthesis, which uses CO2 and water to make sugar and oxygen. Since photosynthesis occurs in the leaves of the plant.

Is the role of the xylem to move the water from the roots to these leaves so that photosynthesis can occur?

And the phloem transports the products of photosynthesis around the plant. Does this also include oxygen, or is it only sugar that is transported by the phloem. Does it also transport water, since water is also a product of photosynthesis?