[Campbell Biology P.849] Which of the following statements about phloem sap translocation in... | Practice Question

Which of the following statements about phloem sap translocation in angiosperms is correct?

  • A: Phloem sap primarily moves by diffusion, which is a very rapid process.
  • B: The movement of phloem sap from source to sink is driven by positive pressure, also known as pressure flow.
  • C: The pressure-flow hypothesis suggests that sap flows from sink to source.
  • D: Phloem sap moves at a maximum rate of approximately 1 cm/hr.

Explanation

The text clearly states that phloem sap flows from source to sink at rates as great as 1 m/hr by bulk flow driven by positive pressure, known as pressure flow. This is much faster than diffusion or cytoplasmic streaming. The pressure-flow hypothesis explains this movement.