lesson
Plants build food molecules using light
1 · Learn
Photosynthesis uses light energy to make glucose from carbon dioxide and water, releasing oxygen. Chlorophyll in chloroplasts absorbs light. Roots provide water and mineral nutrients; soil is not the plant's ready-made food supply.
Glucose can be used in respiration, stored or used to build other substances. Plants also respire: photosynthesis does not mean a plant has no need to release energy from food molecules.
2 · Worked example
I distinguish water entering through roots from carbon dioxide entering leaves. Both are reactants, while light provides energy rather than being a material atom in the products.
3 · Your turn
Which is a product of photosynthesis: glucose or carbon dioxide? Does photosynthesis replace all plant respiration?
Check your answer
Glucose is a product. No; plants also respire to support their life processes.
4 · Apply your learning
Create a labelled input-output model of a leaf and distinguish materials from the energy transfer.
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Use supplied data and diagrams unless a qualified adult has approved the practical, equipment and risk assessment. No tasting substances, culturing unknown microbes, mains electricity, flames or hazardous chemical experiments at home. Models simplify reality; ask which assumptions affect the conclusion.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
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