plumiPlant responses: phytochrome, auxin and gibberellins: Edexcel International A Level Biology questions
Edexcel International A Level Biology past-paper questions on 8.4.2 Plant responses: phytochrome, auxin and gibberellins, 2019–2025, with mark schemes and examiner’s reports where available.
All papers
All years
Q6(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ6(b)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(c)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(d)(i)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(d)(ii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ2(a)(i)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ1(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ1(b)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ1(c)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ3(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ6(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ6(c)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFYour answerQ6(b)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(c)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ6(d)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ3(b)(i)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ3(b)(ii)
The whole paper ↗Loading the start of the question…
Loading the question…
Open the full PDFQ5(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ7(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDF
All 23 questions on Plant responses: phytochrome, auxin and gibberellins, as a list
- June 2025, Unit 5, Q6(a) (1 mark): Which molecule detects light during germination of seeds? (1) A chlorophyll B phytochrome C retinal D rhodopsin
- June 2025, Unit 5, Q6(b) (4 marks): The effect of red, blue and white light at low and high light intensities on the growth of peanut seedlings was investigated. The photograph shows a peanut seed
- June 2025, Unit 5, Q6(c) (4 marks): Auxin stimulates: • the release of hydrogen ions that disrupt cellulose microfibrils • the uptake of potassium ions by cells. Explain how auxin causes cells to
- June 2025, Unit 5, Q6(d)(i) (2 marks): Calculate the percentage change in germination between 200 ppm and 400 ppm gibberellin concentration. (2) Give your answer as a whole number. Answer %
- June 2025, Unit 5, Q6(d)(ii) (2 marks): Explain how gibberellins affect germination in this investigation. (2)
- October 2024, Unit 5, Q2(a)(i) (1 mark): Which is a function of gibberellins in plants? (1) A hydrolyse starch to release glucose B inhibit elongation of cells C regulate the translation of DNA D regul
- October 2024, Unit 6, Q1(a) (1 mark): State why germinating wheat grains need to produce amylase. (1)
- October 2024, Unit 6, Q1(b) (6 marks): The drawing shows a wheat grain and the locations of the endosperm and the embryo. endosperm embryo Describe an experiment to determine if gibberellin stimulate
- October 2024, Unit 6, Q1(c) (3 marks): Describe how gibberellin increases amylase synthesis. (3)
- June 2024, Unit 5, Q3(b) (3 marks): Plants also respond to their environment. The diagram shows a seedling with the apical bud and a lateral bud labelled. apical bud lateral bud In an investigatio
- October 2023, Unit 5, Q6(b) (1 mark): Which is a description of a gibberellin? (1) A an enzyme that converts starch to glucose B a molecule that converts phytochrome far‑red (Pfr) to phytochrome red
- October 2023, Unit 5, Q6(c) (6 marks): The quality and length of daylight act as signals to initiate and regulate flowering in plants. This involves phytochromes and the production of gibberellins. I
- October 2022, Unit 5, Q6(a) (1 mark): Phytochrome molecules are found in plants. Phytochrome exists in two forms, Pr (P660) and Pfr (P730). Which row shows the action of these two forms of phytochro
- October 2022, Unit 5, Q6(b) (3 marks): Auxins (IAA) are plant growth substances. The diagram shows auxin molecules producing a phototropic response in a shoot. auxin molecules Explain the role of aux
- October 2022, Unit 5, Q6(c) (4 marks): Seeds contain starch. This starch is used to supply energy when the seed germinates. Gibberellins are a group of naturally occurring plant growth substances. Gi
- October 2022, Unit 5, Q6(d) (4 marks): Indole acetic acid (IAA) is a natural plant auxin. 1-Naphthaleneacetic acid (NAA) is a synthetic auxin. The effects of these two auxins on the growth of Chlorel
- June 2022, Unit 5, Q3(b)(i) (2 marks): Comment on the effect of the gibberellin on the growth of cereal plants. (2)
- June 2022, Unit 5, Q3(b)(ii) (3 marks): Suggest how the gibberellin causes this effect. (3)
- January 2022, Unit 5, Q5(b) (6 marks): The drawing shows the results of some experiments investigating phototropisms. The diagram shows a coleoptile of a seedling. coleoptile roots Experiment 1: ligh
- June 2021, Unit 5, Q7(b) (6 marks): Exposure to light controls the germination of seeds and the direction of growth of plants. In an investigation the seeds of plantains were exposed to light. The
- January 2021, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
- January 2021, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
- January 2021, Unit 6, Q4(d) (2 marks): Suggest two limitations of your proposed method. (2)
Questions, mark schemes and examiner’s reports are © Pearson Edexcel, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Edexcel International A Level Biology past papers.
The Plumi iPad app also offers exam-style questions with AI feedback on your handwritten working.