CAIE A-Level Biology A2 16.2.5 Gibberellin Role in Stem Elongation Questions
Explain the role of gibberellin in stem elongation using evidence from each question and mark scheme.
- Syllabus
- 2028–2030
- Course
- Biology 9700
- Level
- A2
Exam points
- Explain the role of gibberellin in stem elongation.
CAIE A-Level Biology A2 16.2.5 Gibberellin Role in Stem Elongation Questions question 1
[Maximum number: 3]
Some plants are grown commercially for their flowers. Many of these plants are varieties that have short stems.
Two factors that affect the height of stems are:
- gibberellin
- the Le/le gene.
The Le/le gene has two alleles, Le and le.
Explain how the Le/le gene and gibberellin are involved in affecting the height of plant stems.
any three from:
short/dwarf, plants:
1 are, homozygous recessive / lele ;
2 le / recessive allele, codes for, non-functional / no, enzyme ;
3 le / recessive allele / non-functional enzyme, gives inactive gibberellin ;
4 DELLA proteins, not broken down / stay bound to PIF ;
5 PIF cannot, bind to promoter / start transcription ;
6 of gene(s) that promote, growth / cell division / cell elongation ;
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