7.9 investigating transport in plants

Question 1

what is the ringing experiment?

Answer 1

removing ring of protective layer & phloem

Question 2

what is the result & explanation of the ringing experiment?

Answer 2

accumulation of sugars above ringed section -> swelling shows that the transport of sugar has been interrupted

Question 3

what measurements have been taken to protect young trees?

Answer 3

protection around lower stems

Question 4

how is the tracer experiment carried out? how does it show that phloem transports sugars in plants?

Answer 4

1) C14 used to make C(14)O2 & plant is grew -> C14 is incorporated into sugars during photosynthesis
2) autoradiography is used to track movement
3) cross-section is placed on x-ray films
4) blackened region corresponds to phloem which shows it is responsible for sugar transportation

Question 5

what are some evidence that translocation of organic molecules occur in the phloem? (3)

Answer 5

• organic molecule solution flows out when phloem is cut
• aphids feed on plants by penetrating the phloem
• daily variations of sucrose levels are mirrored by identical variations in the phloem