Plant hormones (biology only) revision notes

Plant hormones (biology only) is part of Homeostasis and response in AQA GCSE Biology 8461. This revision note keeps revision tied to the approved curriculum so students can move from broad understanding into precise exam-ready explanations without drifting away from the specification.

Across 2 subtopics, the topic covers 19 approved learning objectives. Students should revise the language of each objective, identify the biological process or example it refers to, and then practise explaining the idea clearly in context.

Control and coordination is a core part of Plant hormones (biology only). Students should understand that Describe plant hormones as chemicals that coordinate and control plant growth and responses. Explain that plants respond to light and gravity using unequal distributions of plant hormones. Describe phototropism as a plant growth response to light. Describe gravitropism, or geotropism, as a plant growth response to gravity. Explain how unequal distribution of auxin causes unequal growth in shoots and roots. Explain (HT only) that gibberellins are important in initiating seed germination. Explain (HT only) that ethene controls cell division and fruit ripening. State (HT only) that the detailed mechanisms of gibberellin and ethene action are not required. Useful keywords here include plant hormones, gravity, light, and phototropism. Important terminology includes plant hormones, coordination, Phototropism, Gravitropism, phototropism, and light. A helpful exam reminder is to memorize the key types of plant hormones and their functions in coordinating growth and responses.

Use of plant hormones (HT only) is a core part of Plant hormones (biology only). Students should understand that Describe (HT only) the use of auxins as selective weed killers. Describe (HT only) the use of auxins as rooting powders for plant cuttings. Describe (HT only) the use of auxins in tissue culture. Describe (HT only) the use of ethene to control fruit ripening during storage and transport. Describe (HT only) the use of gibberellins to end seed dormancy. Describe (HT only) the use of gibberellins to promote flowering. Describe (HT only) the use of gibberellins to increase fruit size. Evaluate (HT only) agricultural and horticultural uses of plant hormones, including benefits, risks and effects on biodiversity. Useful keywords here include auxins, HT only, weed killer, and rooting powder. Important terminology includes auxins, selective weed killers, rooting powder, and tissue culture. A helpful exam reminder is to focus on how auxins are used as selective weed killers by disrupting the growth of unwanted plants while leaving desirable crops unharmed.

When revising Plant hormones (biology only), students should move beyond memorising isolated facts. Strong answers link the biology to the right subtopic, use precise scientific vocabulary, and explain why a symptom, treatment, defence, or investigative method matters in the wider topic.

A reliable revision routine is to read the subtopic summary, learn the key terms, answer practice questions, and then check whether the explanation still matches the approved learning objective. This prevents vague answers and helps students build confidence with both short recall questions and longer written responses.

Revision focus 1: in Control and coordination, students should be able to describe plant hormones as chemicals that coordinate and control plant growth and responses. This is stronger when the explanation stays in the context of Plant hormones (biology only) and uses exact biological vocabulary rather than generic statements.

Revision focus 2: in Control and coordination, students should be able to explain that plants respond to light and gravity using unequal distributions of plant hormones. This is stronger when the explanation stays in the context of Plant hormones (biology only) and uses exact biological vocabulary rather than generic statements.

Revision focus 3: in Control and coordination, students should be able to describe phototropism as a plant growth response to light. This is stronger when the explanation stays in the context of Plant hormones (biology only) and uses exact biological vocabulary rather than generic statements.

Revision focus 4: in Control and coordination, students should be able to describe gravitropism, or geotropism, as a plant growth response to gravity. This is stronger when the explanation stays in the context of Plant hormones (biology only) and uses exact biological vocabulary rather than generic statements.

Revision focus 5: in Control and coordination, students should be able to explain how unequal distribution of auxin causes unequal growth in shoots and roots. This is stronger when the explanation stays in the context of Plant hormones (biology only) and uses exact biological vocabulary rather than generic statements.