Plant structures Flashcards
What is the function of companion cells ?
They carry out processes for themselves and the sieve cells, due to the lack of organelles
eg. active transport of solutes to provide energy
What is the function of a sclerenchyma fibre ?
to provide support for the stem
What are the two plant fibres that are useful to humans ?
- Arrangement of cellulose microfibrils in the cell wall
2. secondary thickening of the cell walls
why is cellulose a useful plant fibre for human use?
The cell wall contain CELLULOSE MICROFIBRILS IN NET-LIKE ARRANGEMENT , this arrangement gives the plant fibres STRENGTH
Whys is the secondary thickening of the cell walls useful to humans?
The secondary cell wall is THICKER than the normal cell wall due to the presence of LIGNIN therefore making them STRONGER
describe secondary thickening and explain how this relates to the properties of plant fibres
- secondary thickening is the production of another cell wall between the normal cell wall and the cell membrane,
- its is thicker and has more lignin than the normal cell wall, giving it more strength
What is meant by the term tensile strength of a fibre ?
the maximum load it can take before it breaks
how can we test for the tensile strength of a plant fibre ?
- attach a plant fibre to a clamp stand , attached to a weight
- keep adding weights until the plant fibre breaks
- record the mass needed to break the plant fibre, the higher the mass the higher the tensile strength
What precautions should be taken in this experiment
- wear goggles
2. stand clear from the weights when they drop
what are two control variables in this experiment ?
temperature and humidity
Describe the arrangement of cellulose fibres and explain how this relates to the properties of plant fibres
- The cell wall contains cellulose microfibrils in a net-like arrangement
- the strength of the microfibrils and their arrangement in the cells makes the fibres strong
why are plant fibres sustainable ?
They are renewable and can be regrown once used
