Chapter 12 Study Questions

  1. Explain the concepts of source and sink in phloem transport.

    Textbook Reference: 12.1 Pattern of Translocation: Source to Sink

  2. Describe the anatomy of a sieve element and the role its companion cell plays.

    Textbook Reference: 12.2 Pathways of Translocation

  3. A sucrose molecule is synthesized in the chloroplast stroma of a mesophyll cell. Describe the path that the sucrose molecule would follow to become part of the phloem sap.

    Textbook Reference: 12.3 Phloem Loading

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

    Textbook Reference: 12.4 Long-Distance Transport: A Pressure-Driven Mechanism

  5. Describe the pressure-flow model of translocation in the phloem. Does water move down its water potential gradient in this model?

    Textbook Reference: 12.4 Long-Distance Transport: A Pressure-Driven Mechanism

  6. What is transported in the phloem from source to sink?

    Textbook Reference: 12.5 Materials Translocated in the Phloem

  7. 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: 12.6 Phloem Unloading and Sink-to-Source Transition

  8. Explain the concept of allocation and partitioning in phloem transport

    Textbook Reference: 12.7 Photosynthate Distribution: Allocation and Partitioning

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