# A student is investigating the rate of transpiration in a plant using a potometer. They measure the distance a bubble moves along a capillary tube over a 10-minute period. 

Describe how the student could ensure the reliability of the measurements taken during this investigation.

> OCR A-Level Biology A (H420) — 1 Development of practical skills in biology · Describe · 4 marks

## Mark scheme (4 marks)

1. Repeat the measurement multiple times for the same conditions/plant.
2. Calculate a mean/average from the repeated measurements.
3. Identify and discard/ignore any anomalous results before calculating the mean.
4. Ensure all relevant controlled variables are kept constant throughout the experiment.

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-the-rate-9d6c13c7) · Published by Druglandscape Ltd.