Pack 7 - Plants Flashcards
1
Q
What is mass transport?
A
- movement of materials over large distances
- due to pressure differences
2
Q
What is the function of the phloem tissue?
A
- transport of organic substances such as sugar
- these organic substances are soluble products of photosynthesis
3
Q
What is the function of the xylem tissue?
A
- transport of water and dissolved minerals
- from the soil
- through the roots
- and then to the stem and to the leaves
4
Q
What is transpiration?
A
- process of water movement through a plant
- water evaporates from the leaves
- there are continuous columns of water
- these ccs move up through the plant and are known as the transpiration system
5
Q
Summary of the transpiration system?
A
- plants absorb 1% of water entering roots
- this is used in photosynthesis and maintaining turgidity
- the remaining 99% is evaporated from leaves
- transpiration rates in large trees can be as high as 1dm^3 min^-1
6
Q
Movement of water from the leaves?
A
- water is carried in the xylem tissue
- this is a series of continuous tubes called xylem vessels
- these are modified dead cells arranged end to end
7
Q
What is the cohesion tension theory?
A
- evaporation of water from the leaves
- pulls more water up the xylem from the stem
- water molecules polar so H bonds make them stick together
8
Q
What is translocation?
A
- mass flow of organic solutes
- such as sucrose and amino acids
- from ‘sources’ to ‘sinks’
9
Q
Where does translocation occur
A
- occurs in phloem
- phloem is made of sieve tube elements
- companion cells are associated with STEs
10
Q
What is the structure of the phloem tissue?
A
- sieve tube elements links with the sieve plate
- sieve tube has little cytoplasm, no vacuole, and few organelles (a few mitochondria)
- sieve tubes are alive due to plasmodesmata connections with companion cells
- each companion cell has a nucleus, many mitochondria and other organelles
11
Q
What is a source?
A
- where the organic solutes are produced
- highest concentration
12
Q
What is a sink?
A
- where the organic solutes are used up
- lowest concentration
