Investigating transport in plants

Question 1

What are tracer experiments

Answer 1

When radioactive isotopes are used for tracing the movement of substances in plants.
Carbon -14 can be used to make CO2, absorbed into plant to make sugars using carbon -14. Carbon -14 can be detected using x rays. Transport systems will not blacken as carbon -14 is present

Question 2

What are ringing experiments

Answer 2

The removal of a ring of phloem vessels and protective layering from woody stems.
Region above the ring swells up from sugar accumulation, region below suffers interruption and tissue death
Proves sugars are transported in phloem and not xylem

Question 3

Evidence for translocation in phloem

Answer 3

When cut, solution of organic molecules flow out
During tracing, radioactive carbon can be seen present in phloem
Aphids have needle mouthpieces to penetrate phloem and extract contents of sieve tubes