This lesson describes the role of gibberellin in stem elongation, and considers the experimental evidence which supports this theory. The PowerPoint and accompanying resources have been designed to cover specification point 5.1.5 (d) as set out in the OCR A-level biology A specification.
The lesson begins with the introduction of the Le gene loci, along with some initial details of this gene’s regulation of height in some plants. The students met gibberellin in a previous lesson in this module on the roles of plant hormones, so the first of several prior knowledge checks is used to challenge them to recall the name of this plant hormone from a description about seed germination. Moving forwards, the students will learn that the enzyme encoded for by the Le gene is involved in the gibberellin synthesis pathway, where it catalyses the conversion of the inactive precursor GA20 to GA1, which is active gibberellin. As this lesson is normally taught before patterns of inheritance in module 6.2.1, a step-by-step guide is used to describe how to use a genetic diagram to predict the phenotypic outcomes. An exam-style question is used to ensure that students recognise that homozygous dominant and heterozygous genotypes would be expressed as tall plants.
The next part of the lesson considers the recessive allele, and how the substitution of alanine with threonine affects the shape of the active site, rendering the enzyme as non-functional.
The final part of the lesson looks at examples of investigations which have been used to obtain experimental evidence which support the theory of the role of gibberellin in stem elongation.
All answers to the knowledge checks are embedded into the PowerPoint to allow students to assess their progress.
The role of gibberellin in seed germination is covered in “The roles of plant hormones” lesson which has been uploaded for free.
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Module 5.1.5: Plant and animal responses (OCR A-level Biology A)
All 11 lessons included in this bundle are detailed and contain a wide variety of tasks to challenge and engage the students whilst covering this potentially difficult topic. The content of this module, titled plant and animal responses, is regularly assessed in the PAPER 1 and 3 OCR examinations, so these lessons have been filled with assessment-style questions to continually expose the students to this type of material. The following specification points are covered by this bundle: 5.1.5 a, b, d, g, h, i, k, and l. If you would like to sample the quality of the lessons before committing to the bundle, then why not download the role of plant hormones, organisation of the nervous system and sliding filament theory lessons, as these have been shared for free?
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Plant responses (OCR A-level biology A)
This mini-bundle covers key content in the plant half of module 5.1.5, which is titled "Plant and animal responses". The students knowledge and understanding of the plant topics tends to be weaker than that of the animals, so these 3 lessons have to be planned at length to break the content down into smaller chunks and there are multiple opportunities for understanding to be checked. If you would like to sample the quality of these lessons and the time that has been put into their design, then why not download the "role of plant hormones" lesson as this has been shared for free.
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