2019 Year 12 IB Extended Essays

Exposure to sunlight

All the plants will be grown indoors using artificial lights to more effectively control the environment within which the plants are growing

This will be done to ensure that all the plants photosynthesize at the same rate and is not affected by a difference in exposure to sunlight. This also reduces the rate of evaporation of the water when compared to sunlight. The water will not be topped up with more of the prepared solutions because when the water evaporates from the cups, the salt will be left behind, increasing the concentration of the solution, this increase will be countered by adding de-ionised water, maintaining the concentration of the nitrates and salt. This ensures that the mass and size of the plants are approximately similar to each other to reduce the effect that a difference in size has on the experiment This ensures that all the cotton beds had the same levels of saturation as the other and to ensure that all the plants got the same volume of their respective solutions

Composition of supplemental water

The water that will be used to top- up the water in the cups will be de- ionised water

Mass of the plant

The plants will be grown from seeds rather than using grown plants

Mass of the cotton

All the cups had exactly 1g of cotton as a base

Considerations: - The seeds could develop mould which could cause allergic reactions within certain

individuals and be potentially deadly. - There are no ethical considerations - There are no environmental concerns

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