lesson
Cells contain structures with different jobs
1 · Learn
Cells are the basic units of living organisms. A typical animal cell has a membrane controlling movement of substances, cytoplasm where many reactions happen, a nucleus containing genetic information and mitochondria involved in aerobic respiration.
A typical photosynthetic plant cell also has a cellulose wall, chloroplasts and a large permanent vacuole containing cell sap. Not every plant cell contains chloroplasts: many root cells do not. A simplified diagram is a model, not a photograph of every cell.
2 · Worked example
I compare a leaf cell and a root cell. Both are plant cells, but chloroplasts are expected in many light-exposed leaf cells rather than every root cell.
3 · Your turn
Why is 'all plant cells contain chloroplasts' too broad?
Check your answer
Some plant cells, including many root cells, do not photosynthesise and lack chloroplasts.
4 · Apply your learning
Label approved cell diagrams and explain two similarities and two differences without relying only on their outline shape.
Adult guidance and safety
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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Year 7 Science learning routine
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