Investigating Transpiration in Plants

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Investigating Transpiration in Plants

Hypothesis

I predict that the plant will loose more water through transpiration

when the fan is closer to the plant. I think that the distance of the

fan from the plant and the water loss are inversely proportional, that

is the greater the distance between fan and plant, the smaller the

percentage loss of mass.

I predict also that at a certain distance, the fan will no longer have

an effect, or minimal effect, on the transpiration of the plant and

the water loss will be constant. At this point the best fit line will

be a near-horizontal line close to the axis, showing virtually zero

water loss (excluding evaporation and other effects). These two

predictions together suggest that the best fit for the two trends

described will be a curve as shown..

Analysis (see graph overleaf)

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The graph shows the relationship between the distance of the fan from

the plant, and the % change of mass in the plant.

From the graph, I can see that:-

1. The plant is losing water/transpiring when placed near a fan,

because all the % changes in mass are negative numbers, and this shows

the mass is going down.

2. There is an anomalous result at 100cm. This is so far away from the

other readings that it should be disregarded.

3. There is a pattern in my results, disregarding the anomalous

result. I can see that there is the greatest water loss when the fan

is closest and least at the furthest distance. For example, at 40cm

the % change of mass is -0.31%, and at 60cm the % change of mass is

-0.28. It is losing more water when the fan is closest, so the water

loss is inversely proportional to the distance of the fan from the

plant. The line of best fit illustrates this trend.

Explanation of Conclusion:

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Transpiration happens in the lower half of a leaf, in pores called the

"stomata." Inside the leaf there is a concentration of water vapour

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