4. Discussion

Why does the speed of wind cause the plant to transpire more?

4.1 Analysis of results

After the experiment and analysing our results, we figured that the wind affects the speed of transpiration which causes the dye to travel faster in distance vertically. An example of how we knew this is because the fan speed 3 (weakest) had red dye travelling only up to an average of 11.6 cm while the speed 1 (strongest had red dye travelling up to an average of 16. 4 cm.

4.2 Key findings

As the speed of wind increases, the distance the red dye travelled also increases.

4.3 Explanation of key findings

Transpiration is affected by evaporation. Therefore, any factor that affects the rate of evaporation of water will affect the rate of transpiration. External factors that influence the rate of transpiration are humidity, air movement, temperature and light. (Lam Peng Kwan/Eric Y K Lam, 2013)

Transpiration can be affected by the humidity of the surrounding air. The intercellular air spaces in the leaf are normally saturated with water vapour. There is water vapour concentration gradient between the leaf and the atmosphere. The drier or less humid air outside the leaf, the steeper this concentration gradient is, thus the rate of transpiration will be faster. Increasing humidity in the air will decrease the water vapour concentration gradient between the leaf and atmosphere. Thus, the rate of transpiration will decrease. (Lam Peng Kwan/Eric Y K Lam, 2013)

So if we constantly blow that concentration of water vapour away, the concentration gradient of water vapour in the atmosphere to the leaf will be steeper, causing the rate of transpiration by the plant to increase.

4.4 Evaluation of Hypothesis


Our hypothesis in the beginning was that as the speed of wind increases, so would the rate of transpiration, causing the red dye to move up the stalk faster after the experiment and analysing results and data, our hypothesis is proven correct and supported by evidence.

4.5 Areas for improvement

Area of Limitation
Areas for improvement
Equipment use: Fan
The fan limits us to only 3 speeds when we originally needed 6 speeds because the experiment required 6 independant variable.
We can improve our experiment and get more data if we had a fan with 6 speeds.
With 6 speeds we could gather data for 6 independent variables which is the minimum requirement for the experiment which we did not meet due to limitation.
Procedure: Working more efficiently with chopping the celery
This limits us as air may be drawn into the stem, creating a pocket of air or an embolism that prevents water absorption.
We can cut the celery stalk underwater to prevent pockets of air.
Pockets of air or an embolism prevents the celery stalk from absorbing water.
Procedure: Being a more efficient experimenter
Distractions around us cause us to drift away from the experiment sometimes.
Put away distractions from our sight and vicinity.
Distractions take our attention and therefore cannot pay attention to the experiment and our work.
Procedure: Doing the experiment at the same time of the day
Because we are only allowed to use ISS periods for experimentation, we cannot change the timing of day we do the experiment.
We could maybe do the experiment at home where we can do the experiment on the same day and weather.
The weather and time really is a limitation because maybe it is sunny, and the air may be dry, water vapour concentration gradient would be steeper. While on the 2nd day of the experiment, it may be a rainy day, so  there would be a less steeper water vapour concentration gradient.

Some areas of improvement would include:

  • Cutting the celery underwater

  • Not getting distracted while doing our experiment
  • Weather and Time can be more accurate if we had done the experiment in similar weather and time of day.
  • We can be more accurate in measuring the surface area of leaves exposed rather than the only counting the number of leaves.

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