Chapter 11 Study Questions

  1. Describe the anatomy of a sieve element.

    Textbook Reference: Pathways of Translocation, pp. 287–291

  2. Describe the pressure-flow model of translocation in the phloem. Does water move down its

    water potential gradient in this model?


  3. Textbook Reference: The Pressure-Flow Model, a Passive Mechanism for Phloem Transport, pp. 295–297

  4. What is a typical velocity of sap moving in the phloem? Can phloem sap move at this velocity by diffusion?

    Textbook Reference: Rates of Movement, pp. 295; The Pressure-Flow Model, a Passive Mechanism for Phloem Transport, pp. 295–300

  5. A sucrose molecule is synthesized in the chloroplast stroma of a mesophyll cell. Describe the path that the sucrose molecule would follow if it were to become part of the sucrose pool in a developing seed.

    Textbook Reference: Phloem Loading, pp. 300–303

  6. Explain the concepts of source and sink in phloem transport. Leaves are said to be sinks early in development and to become sources as they attain photosynthetic competence. Which experiments would provide information about the leaf transition from sink to source?

    Textbook Reference: Phloem Unloading and Sink-to-Source Transition, pp. 305–308