The presence of gibberellins in a plant cell leads to the expression of genes involved in stem elongation. Describe how gibberellin causes stem elongation in plants.

Mark scheme

Marking points from the official mark scheme (May/June 2025). The mark or mark type is shown in brackets.

1. [6] any six from: 1 gibberellin binds to (gibberellin) receptor (-enzyme-complex) ; 2 DELLA (protein) destroyed ; 3 transcription factor / PIF, released / free / no longer bound to DELLA ; 4 transcription factor / PIF / RNA polymerase, binds to, DNA / promoter ; 5 growth / expansion / XET / xyloglucan endotransglucosylase, gene, switched on / expressed / transcribed ; 6 loosens cell walls / breaks bonds between cellulose ; 7 water enters (cells) by osmosis causing cell elongation ; 8 AVP;