IB Biology HL 1.2.1 Transcription and gene regulation Question Bank
Practise IB Biology HL 1.2.1 by analysing transcription at the molecular level and linking it to gene regulation.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Analyse template-strand use, RNA polymerase action and complementary pairing during transcription.
- Explain how transcriptional activity changes mRNA production and gene expression.
- Evaluate a transcription explanation by checking strand orientation, enzyme role and product.
D1.2.1—Transcription question 1
Auxin can be used to promote the development of roots from stem and leafy cuttings in some plants. In a study into the distribution of auxin in the development of these roots, scientists measured the amount of auxin in different leaves of a shoot tip of Petunia hybrida.
The figure indicates the numbering of leaves on the shoot, from L1 as the youngest and smallest to L6 as the largest and oldest leaf. The developmental stage of L5 and L6 was very similar, so L5 was not analysed. The stem base is the lowest part of the cutting where roots may form.
The graph shows the auxin concentration in the different leaves.
The scientists wanted to know whether the accumulation of auxin over time in the stem base of the controls affected expression of the GH3 gene, known to have a role in growth regulation in different plants. The technique that was used to quantify the level of transcription of the GH3 gene was Northern blotting. In this procedure the darkness and thickness of the band is an indicator of the level of transcription of a particular gene. The image shows the result of the Northern blot from 2 hours to 24 hours after cutting.
State the name of the molecule which is produced by transcription.
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