Question

	Transpiration
What is transported?
In xylem or phloem?
Direction of flow
Cells involved (note alive or dead, which plant groups have them, function)	Tracheids:
	Vessel elements:
Does this process require the plant to expend energy?
Explain how movement is achieved (how does this work?)

Answer 1

Ans) Water and minerals can be transported via xylem (It transports them from roots to stem and leaves and also replace the water lost through transpiration.So,transpiration is the main process which drives the movement of water and minerals through xylem. Transport through xylem is unidirectional (upward direction) and does not require ATP for transport.Transpiration pricess generates negative pressure in the leaves of xylem and thus water moves upwards.

Phloem can transport sucrose,nitrogen (in the form of amino acids and amides),mannitol,P-protein filaments,sorbitol etc. Transport through phloem is Bidirectional and requires energy in the form of ATP.Sucrose enters sieve tubes (Hypertinic) and thus water moves from neighbouring cells to sieve tubes by osmosis (movement of water from low concentration to higher concentration),due to which pressure rises and food is transported from one sieve tube to another.Transport in phloem is also known as Mass flow hypothesis (Source to sink transport).

Most vascular plants have the presence of xylem and phloem while nonvascular plants such as belonging to Bryophyta like liverworts,mosses etc lack them.