[Campbell Biology P.897] What is the primary reason for the unidirectional polar transport o... | Practice Question

What is the primary reason for the unidirectional polar transport of auxin from the shoot tip to the base?

  • A: Auxin is denser than other plant hormones, causing it to sink.
  • B: The plant's vascular tissue is designed to only allow downward flow.
  • C: Auxin transport proteins are primarily localized at the basal ends of cells, facilitating one-way movement.
  • D: Gravity pulls auxin downwards within the plant cells.

Explanation

The passage explains that 'the polarity of auxin movement is attributable to the polar distribution of auxin transport protein in the cells. Concentrated at the basal end of a cell, the auxin transporters move the hormone out of the cell.' This specific localization ensures the unidirectional flow of auxin.