Biology 0610 · IGCSE · Sense organs

Sense organs — practice question

A student carried out an investigation into how altering light intensity affected the diameter of the pupil in the eye. The table presents the findings. Initial pupil diameter $= 8\,\text{mm}$, final pupil diameter $= 2\,\text{mm}$. Which explanation of the student’s results is correct?

  • AA reduced light intensity reduced the pupil diameter by $75\%$.
  • BA reduced light intensity reduced the pupil diameter by $25\%$.
  • CAn increased light intensity reduced the pupil diameter by $75\%$.
  • DAn increased light intensity reduced the pupil diameter by $25\%$.

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