Phloem and xylem

• Xylem are made of dead cells joined together by lignin. which strengthens the material to allow the flow of water
• The phloem are made of elongated cells with small pores in the end walls to allow flow
• Phloem transports food substances (mainly sucrose) made in leaves for the rest of the plant for immediate use or storage
• The phloem flow is a process called translocation which requires energy from respiration. The phloem transportation goes both ways ( up and down)
• When plant has lots of water, the guard cell is well hydrated, causing it to become turgid, meaning that the gap between the guard cell widens, allowing more CO2 to diffuse through
• If there is less water, guard cell becomes flaccid as water moves out of it through osmosis, meaning the gap between the guard cell closes to allow conservation of water vapour and no longer take in CO2
• The phloem is designed in sections called the phloem tube and has pores that enable movement of cell sap
• Cell sap is a liquid mixture of water and sugar, the sugar can be used immediately or stored
• The phloem allows flow in both ways and has thinner walls than the xylem walls
• Xylem doesn’t have sections and is strengthened by lignin.
• Xylem transports both water and mineral ions from roots to leaves for photosynthesis
• A steady stream of water in xylem is a transpiration stream
• The movement of water is only one way upwards in the xylem
• What is the difference between the structure of the xylem and phloem?

  The xylem is a continuous tube and is thicker compared to the phloem that has sections