A student carries out an experiment to investigate phototropism in young plant coleoptiles. One group of seedlings with intact, untreated tips is exposed to unilateral light coming from the right side. After 48 hours, these seedling shoots have grown and curved significantly towards the right (the light source).
Suggest how the student can accurately measure the length of these curved shoots at the end of the experiment using a standard flat millimeter ruler.
Explain how the lateral distribution of the hormone auxin in the shoot tip is affected by the unilateral light, and explain how this distribution causes the shoot to bend towards the right.
59 exam-style questions on AQA GCSE Biology 5.4 Plant hormones, covering 5.4.1 Control and coordination and 5.4.2 Use of plant hormones (HT only). Each one has a worked solution and a mark scheme showing where the marks go.