7.9 Investigating transport in plants Flashcards
1
Q
Ways of investigating translocation in plants
A
- ringing experiments
- tracer experiments
- aphids
2
Q
How do ringing experiments work?
A
- cut protective layer and phloem around woody stem
- stem immediately above will swell
- non-photosynthetic tissues bellow wither and die
3
Q
What is the substance found above the ring rich in?
A
- sugars
- dissolved organic substances
4
Q
What does the ringing experiment show?
A
- interruption in the flow of sugars below the ring
- phloem and not xylem is responsible for translocating years
5
Q
How does the tracer experiment work?
A
- cut thin cross sections of plant grown in 14CO2
- place on x-ray film
Blackened film = 14C
No Blackened film = no 14C
6
Q
What is the explanation for the type of plant used in tracer experiments?
A
Isotope 14C is used to make 14CO2
Plants grown in 14CO2 have 14C incorporated in the sugars
7
Q
What does the tracer experiment show?
A
- blackened tissue is phloem
- only phloem carries sugars
8
Q
How are aphids used to investigate transport in plants?
A
- needle like mouthparts
- penetrate the phloem
- extract contents from sieve tube
9
Q
What do aphids show?
A
- shows daily variation in the sucrose contents of leaves
- mirrored in the phloem
