[Campbell Biology P.897] If auxin transport proteins were equally distributed at both ends a... | Practice Question

If auxin transport proteins were equally distributed at both ends apical and basal of the plant cells, how would this affect polar auxin transport, and why?

  • A: Polar transport would still occur, but at a slower rate, as distribution only affects efficiency.
  • B: Polar transport would cease because auxin would exit both ends of the cell, preventing a directional flow.
  • C: Auxin transport would reverse, flowing from base to tip, because the basal proteins would then act as apical.
  • D: Auxin would accumulate within cells, as it could not exit efficiently from either end.

Explanation

The passage states that the polarity of auxin movement is due 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. The auxin can then enter the apical end of the neighboring cell'. If these proteins were equally distributed, auxin would be transported out of both ends of the cell, preventing a net unidirectional flow and thus abolishing polar transport.