investigating plant transport

Question 1

give the 3 ways to investigate plant transport

Answer 1

• ringing experiments
• tracer experiments
• aphids

Question 2

Describe the use of ringing experiments to investigate transport in plants

Answer 2

Remove the bark and phloem from the circumference of a tree

A bulge will appear above the ringed area

This contains sucrose

Evidence that the sucrose is being transported in the phloem as it cannot move below the ring so forms a bulge

Question 3

Describe the use of tracer experiments to investigate transport in plants

Answer 3

• Use radioactive carbon to produce carbon dioxide.
• Plant uses the radioactive carbon dioxide to produce glucose
• Sucrose is then transported throughout the plant

-Use X ray film to detect the presence of the radioactive carbon in the plant (autoradiography)”

Question 4

Explain the evidence that translocation of organic molecules occurs in the phloem

Answer 4

• When phloem is cut, solution of organic molecules flow out
• Plants provided with radioactive carbon dioxide have radioactively labelled carbon in their phloem
• Aphids mouthparts penetrate phloem sieve tubes - they can be used to monitor sucrose content of phloem which mirrors daily fluctuations in sucrose content of leaves
• Removal of phloem from the circumference of a stem leads to a build up of sucrose above the ring”