Plant Fibres 4.10-4.12 and 4.15 And CP6 Flashcards
What three tissues are plant stems made from?
1) Xylem Vessels
2) Sclerenchyma fibres
3) Phloem tissue
What is the function of xylem vessels?
Provide support to the plant + transport water and transport mineral ions up the plant
Describe xylem vessels x4
- Long, tube-like structures formed from dead cells that are joined together
- The cells contain a hollow lumen (no cytoplasm) and have no end walls
- Contain secondary thickening with lignin to support the plant
- Pits in the walls don’t contain lignin to allow water and minerals to move in and out of vessels
What is the function of sclerenchyma fibres?
To provide support
Describe sclerenchyma fibres
Made of dead cells that contain a hollow lumen and secondary thickening (like xylem) but contain end walls and don’t have pits
Contain lots of cellulose
What is the function of phloem tissue?
Translocation of organic solutes (mainly sugars) - purely a transport tissue
What two cell types make up phloem tissue + describe each
Sieve tube elements = living cells joined end-to-end with end walls that have lots of holes for solutes to pass through BUT no nucleus, a thin layer of cytoplasm and few organelles SO cannot survive on their own
Companion cells = carry out living functions for sieve tubes as well eg. provide energy for active transport of solutes
What is a vascular bundle?
A group composed of xylem vessels and phloem tissue
Describe an experiment to identify xylem vessels, phloem tissue and sclerenchyma fibres using a light microscope
1) Use a scalpel to cut a cross-section of the stem very thin
2) Place the cut stems into water until use to prevent drying out
3) Transfer sections to a stain (toluidine blue O or TBO) and leave for one minute - stains lignin blue/green so xylem and sclerenchyma can be observed and phloem will appear pink
4) Rinse off sections in water and mount on a slide
5) Observe
What are plant fibres made from?
Long tubes of plant cells eg. Sclerenchyma fibres and xylem vessels are made of dead cells
What can plant fibres be used to make
Ropes or fabrics like hemp
What two ways are plant fibres strong?
1) The cell wall contains cellulose microfibrils arranged in a net-like arrangement
2) Structural plant cells (sclerenchyma and xylem) contain a secondary cell wall which is thicker than the normal cell wall and contains lots of lignin in a process called secondary thickening
What does it mean if something is sustainable?
Using resources in a way that meets the needs of the present generation without depleting the resources for future generations
What are renewable resources?
Resource that can be used indefinitely without running out
Give an example of a sustainable practice
Replacing tres after logging by replacing cut down ones with a new one in its place so the environment isn’t damaged in the long term
