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CAIE IGCSE Biology 22.3.2 Geometry Measurement and Biological Scales Questions

Practise metric conversions, geometric volume and concentration calculations, and area-based biological comparisons with appropriate units and precision.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • convert between metric units including area and volume and select the appropriate unit
  • calculate volume of a common shape such as a cylinder using radius, height and π
  • calculate concentration from a known grid/chamber volume and counted cells
  • normalize a biological measurement by leaf area or another stated surface dimension for valid comparison

CAIE IGCSE Biology 22.3.2 Geometry Measurement and Biological Scales Questions question 1

[Maximum number: 1]

Scientists measured the rate of photosynthesis in the leaves of a sunflower plant, Helianthus annuus.

The scientists used the apparatus shown in Fig. 3.1 to measure the rate of photosynthesis.

Fig. 3.1

Fig. 3.1

The scientists carried out another investigation using the same apparatus at different temperatures.

They measured the rate of uptake of carbon dioxide in the light and then they measured the rate of release of carbon dioxide in the dark.

The results are shown in Fig. 3.2.
rate of carbon dioxide uptake and release /μg/ \mu \mathrm{g} per hour per cm2\mathrm{cm}^{2} of leaf

Fig. 3.2

Fig. 3.2

Explain why the results in Table 3.1 are expressed as 'per cm2\mathrm{cm}^{2} of leaf' rather than 'per leaf'.

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