2.4.7 Plant Transport and Strength Flashcards
What is the structure of a vascular bundle?
Each vascular bundle contains xylem vessels and phloem sieve tubes, all surrounded by sclerenchyma tissue
What are the two types of cell which provide strength and mineral transport?
Xylem vessels and sclerenchyma tissue
What do the xylem carry?
Xylem vessels carry water and inorganic ions up through the stem
What do the phloem transport?
Phloem vessels transport sugars made by photosynthesis in the leaves and up and down the stem
How is the xylem waterproofed?
The xylem is waterproofed by lignin being impregnated into the cell walls
What happens to the cell as they become lignified?
The tonoplast breaks down, causing autolysis
What is autolysis?
The cell organelles, cytoplasm, and cell membranes break down due to enzymes, then leaving an empty tube
What gives the xylem its strength?
The cellulose microfibrils and lignin give the xylem its strength
How does water move through the xylem?
- water vapour diffuses out through the stomata down a diffusion gradient
- water evaporates from the surface
- water is replaced by capillary action within the cell walls
- water is drawn out the xylem
- a continuous column of water is drawn up through the xylem
What is the stream of water passing through the plant known as?
The transpiration stream
What is cohesion-tension theory?
Hydrogen boding between water molecules means the water sticks strongly together, meaning the xylem tube doesn’t collapse
What is the role of nitrate ions in plants?
They are needed to make amino acids and for DNA synthesis
What is the role of magnesium in a plant?
Needed to make chlorophyll
What is the role of calcium in plants?
- needed for growth
- has a role in the cell wall structure and in the permeability of the membrane
What is the role of phosphate in plants?
Needed in ATP
