Transpiration and translocation Flashcards
(6 cards)
What is the structure of xylem tubes and what do they transport ??
made of dead cells joined end to end with no end walls between them and a hole down the middle. They’re strengthened with a material called lignin. They carry water, mineral ions from roots to stem and leaves.
What is the transpiration stream ?
Movement of water from roots through xylem and out of the leaves = transpiration stream
What is the structure of phloem tubes and what do they transport ??
made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
They transport food substances made in the leaves to the rest of the plant for immediate use or for storage
What is translocation ?
The transport goes in both direction.
This process is know as translocation
Translocation is the movement of dissolved sugars and other substances through the phloem from the leaves
Process of Transpiration 1-3
1) transpiration caused by evaporation and diffusion of water from plants surface, most transpiration happens at the leaves
2) This evaporation creates a slight shortage of water in the leaf and so more water is drawn up from the rest of the plant through xylem vessels to replace it
3) This in turn means more water is drawn up from the roots and so there’s a constant transpiration stream of water through the plant.
transpiration is only a side effect of the way leaves are adapted for photosynthesis, so what must they have ?
stomata in them so that gases can be exchanged easily because there’s more water inside the plant than the air outside, the water escapes from the leaves through the stomata by diffusion.
