試題詳解

20. 'Which of the following statements is most compatible with the "source-sink" concept of sugar transport in the phloem?
(A) Sugars are loaded at the sink.
(B) Sugars move from the sink to the source in the phloem.
(C) Sugars are unloaded at the source.
(D) Developing young leaves are sinks and fully developed leaves are sources.
(E) Transport is always unidirectional in the phloem.