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LearnCambridge06102026–2028Papers 1, 3 · CoreOrganisation of the organism
Papers 1, 3 · Module

Organisation of the organism

2 subtopics≈ 75 min in total
Start the module: Cell structureOpen graphing calculator

  1. Cell structure

    All living things are made of cells. Animal cells have a cell membrane (controls what enters and leaves), cytoplasm (where reactions happen), a nucleus (contains DNA, controls the cell), mitochondria (aerobic respiration) and ribosomes (protein synthesis). Plant cells also have a cellulose cell wall (support), chloroplasts (photosynthesis) and a large permanent vacuole (cell sap, keeps cells firm). Bacterial cells have no nucleus: their DNA is a single loop, often with plasmids.

    ≈ 35 min

  2. Specialised cells and magnification

    Cells specialise to do particular jobs: root hair cells have a long extension for absorbing water; red blood cells have no nucleus and a biconcave shape to carry oxygen; sperm cells have a tail and many mitochondria. Similar cells form tissues, tissues form organs, organs form organ systems. Magnification =image sizeactual size=\frac{\text{image size}}{\text{actual size}}, using the same units; 1 mm=1000 μm1\ \text{mm}=1000\ \mu\text{m}.

    ≈ 40 min