2019 Year 12 IB Extended Essays

Limitations and Improvements: Limitation Type of error

Effect on results

Improvement

All the seeds began to develop green and white algae in varying levels

Systematic These algae began to develop on the surface of the cotton base and used

The algae could be systematically removed every day to reduce the impact that it had on the growth of the plants

nutrients and water that was meant for the plants. As the surface area that the algae covered for each plant was different, this would have caused the values of some of the trials to vary as either higher or lower levels of nutrients would have been absorbed by the algae, affecting the concentrations of the NaNO3.

There were fruit flies that landed on the seeds and fed on the seeds.

Systematic As the plants initially use the endoderm as a region for storing food, if this is consumed by the fruit flies, then the plant’s initial growth phases could be affected, causing the plant to grow slowly. But as the fruit flies consumed the seeds at random, this would have had a significant impact on the standard deviation between trials and also on the

A fan could be placed on low setting next to the cups to prevent flies from being able to enter the cups due to the turbulent air

accuracy of the experiment. This is because if the fruit flies consumed larger quantities of the plant grown in 0.4381M NaNO3, then its shoot would take longer to develop and grow due to insufficient levels of nutrients initially.

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