大象传媒

  • Scaling up

    • Supplying the cell - OCR Gateway

      For an organism to function, substances must move into and out of cells. Three processes contribute to this movement - diffusion, osmosis and active transport.

    • Mitosis and cell specialisation - OCR Gateway

      Mitosis is cell division which produces two identical diploid cells for growth and repair. Differentiation occurs when cells become specialised. Stem cells can develop into different cell types.

    • The challenges of size in animals - OCR Gateway

      Larger animals have a lower surface area to volume ratio. This means they need transport systems like our circulatory system and exchange surfaces like our lungs or fish gills.

    • The challenges of size in plants - OCR Gateway

      During transpiration plants move water from the roots to their leaves for photosynthesis in xylem vessels. Glucose made in photosynthesis is then moved to all cells in phloem vessels for respiration.

    • Sample exam questions - scaling up - OCR Gateway

      Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical questions.

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