9.1 Transport Systems In Dictyledonous Plants Flashcards
Why do plants need transport systems?
Relying in diffusion alone would fail to meet the demands of the plant
They have small SA:V ratios
What is the arrangement of the vascular tissues in roots?
Xylem in middle (+ shaped) Phloem in circular tubes around outside Endodermis surrounding xylem and phloem Cortex Epidermis Exodermis Root hair
What is the arrangement of the vascular tissues in stem?
Parenchyma (packaging and supporting tissue) in centre
Vascular bundles in a ring around the edge
Xylem=inner, phloem = outer
Cortex
Epidermis
What is the arrangement of the vascular tissues in leaves?
Vascular bundle in midrib of leaf
Xylem ontop, phloem underneath
What are the key features of the xylem?
Dead cells which have been fused to form hollow vessels, which are strengthened by lignin
Pits in the xylem wall which enable water to move out into adjacent xylem vessels or other cells
Xylem fibres add strength, and parenchyma cells store food
What are the functions of the xylem?
Transport water and mineral ions up a plant
Provide structural support for the plant
What are the key features of the phloem?
Sieve tube elements which are loving cells joined end-to-end, forming a tube with internal pores
Companion cells which carry out all the metabolic functions of the phloem tissue (as the tube lacks nuclei). Material pass into the sieve tube elements via plasmodesmaya
What is the function of the phloem?
Transport of solutes (e.g. sugars and amino acids) up and down a plant
What is the function of lignin in the xylem walls?
- Strengthens xylem wall: prevents collapse of xylem
- Waterproofing: water is under tension and low pressure
- Improves adhesion of water molecules: reduces lateral loss of water through wall
- Spiral patterns allow flexibility/strengthens movement: prevents stem breaking
- Increases capillarity
What is the function of the pits?
- To allow water to move between vessels
- To bypass blockage
- Supply water to other tissues cells part of plants