Xylem, Phloem and Schlerenchya Flashcards
What does the phloem do?
they carry the food produced by photosynthesis
Describe the process of translocation.
- Phloem is made of columns of living, elongated cells.
* Small pores in the ends allow food (mostly sugar) to move up amd down the plant.
Where are the phloem and Xylem found?
In Vascular Bundles
What are sieve tube elements?
One type of cell in the phloem tissue
• they are alive but have no nucleus and few organelles
• they are supported by companion cells ( another type of phloem cell)
How are the companion cell ams sieve tube element held together?
By plasmodesmata
What does the xylem do?
Transport water up the plant from root to leaf
What is the Xylem made out of?
Made up out of dead cells woth no end cell seperating them
• cells are long and wide - no cyptoplasm
• walls are thicken by ligin - supports plant
The continous upward movement of water is called _______
the transpiration stream
What is transpiration cause by?
caused by evaporation amd diffusion.
- water evaporates from the mosit cell walls and bulid up in the air spaces between cells inside the leaf
- this creates a conc gradient
- water vapour diffuses down the conc gradient and out of the leaf
- creates a shortage of water in the leaf
- more water is drawn from the roots through the xylem to replce lost water
- means there is less water in the roots, so the roots take up more water by osmosis
Ate the Xylem and phloem mass transport systems, and why?
Yes because they transport substances over long distances
What is the function of the Sclerenchyma?
Primary function is support
What is the sclerenchyma made out of?
made up of dead cells that run up the stem.
• long hollow tubes - have end walls
• cells are thicken by ligin but have no pits
• More cellulose than other plant cells
What does the sclenerchyma perform?
These cells perform autolysis, hollowing out and dying
Define Translocation.
the movement of solutes around the plant
How does ligin form?
forms during a process called secondary thickening
• this is when xylem and sclerenchyma cells which hve finished growing produce a secondary cell wall between the normal cell wall and the cell membrane.
• 2nd cell wall is thicker than the first cell wall - there is a high proportion of ligin
