1.2.2 Control
The control in this experiment is the 0% salt solution, or in other words the solution without salt. This should help to isolate any invalid effects concerning whether it really was the effect of the salt should the experiment indicate slower growth and germination in the seeds with the saline solutions. For example, if the control with no salt were to germinate and grow even slower than the two saline solutions we could probably assume that our hypothesis was wrong or at the very least that there were other factors involved.
1.3 Experimental Method
1.3.1 Apparatus/Materials
1.3.2. Practical Safety and Risk Assessment
There are few practical safety requirements however, as the experiment is taking place at a residence as opposed to a laboratory instruments such as the measuring cylinder must be washed and kept separated from eating utensils and plates etc. The experiment itself poses no great danger and it can be assumed that the safety, environment and possible costs should an accident take place are ≤ 3 meaning that there is an unlikely risk of an insignificant incident and/or a rare risk of a minor accident taking place. These can be managed under routine safety procedures. There are some minor safety issues outlined as to the use of Sodium Chloride in the form of table salt dealing with inhaling its powdered form (not to be inhaled under any circumstances), skin contact (attempt to avoid exposure especially for prolonged periods due to skin dehydration and irritation) and eye contact (can cause eye damage/irritation). Sodium Chloride in the form to be used in the experiment is by no means hazardous and its use should pose no danger with proper routine safety procedures.
1.3.3 Method
1.3.1 Diagram 1 (Experimental Setup)
1.3.2. Method
- Take the Petri dishes and separate them into halves so that there are, in fact, six dishes.
- Place them on a table in a suitable area with little temperature fluctuation, some sunlight not that much as would cause the seeds to dry out and with minimum disturbance from insects and other factors.
- Take the paper towels and cut them in half
- Fold halves of paper towels into quarters
- Place Petri dish on top of paper towel and trace outline with marker.
- Cut out circle.
- Transfer to Petri dish.
- Label Petri dishes with marker.
- Place 10 seeds per tray evenly into Petri dish on top of the paper towel (see part 2 of 1.2.1 – diagram).
- Create 5% solution by dissolving 5mls of salt into 95mls water in the plastic container.
- Transfer 10mls of 5% solution from plastic container to measuring cylinder.
- Pour 20mls of 5% solution into Petri dishes (a) and (b).
- Create 2% solution by dissolving 5mls of salt into 245mls water in the plastic container.
- Transfer 10mls of 2% solution from plastic container to measuring cylinder.
- Pour 20mls of this solution into Petri dishes (c) and (d).
- Pour 20mls of pure tap water (negligible salt content) into Petri dishes (e) and (f).
- Take a photograph of all the Petri dishes with seeds and then print and annotate the pictures with thereby labelling them giving them each a code (i.e. n1 0%) by which they can be identified.
- Repeat steps 9 to 17 at the same time of day every day for every dish from that day onwards for the next 13 days.
-
At the point at which the seeds sprout (see definition dependant variable: germination - 1.2.1. treatment of variables), make a measurement of their growth on each day onwards until the 14th day of the experiment at which point the experiment will have ended.
2.1.2 Qualitative Data
Photos
One growing shoot (length 12 cms, photo taken on Day 14 of experiment 0% number 3).
Apparent Mould (difficult to see in this grainy picture but manifests itself in the form of the strange whitish brown halo around the clearly darker outline of the seed, photo taken Day 14 of the experiment 5% number 8, not having germinated)
2.1.2. Raw Data and Processing Raw Data
Germination times for 0%, 2% and 5% solutions
Table: Uncertainty ± 1day
N.B. plant numbers 7 and 8 2% and 1, 5, 6, 8 and 9 5% did not germinate
Statistical Analysis
Graph
Growth per day ± 0.5 mm (possible to discern down to the 0.25 of a mm)
End height and Growth average ±0.25mm
Statistical Processing:
Formula for average or mean:
The mean or average = ______ sum of sample measurements
number of samples
Formula for standard deviation:
S = standard deviation
x = each individual value
_
X = mean of all measurements
= deviation from mean
= degrees of freedom
Processed using Excel statistics.
- Conclusion and Evaluation
3.1.1 Conclusion Statement
Germinating wheat seed in a solution of 0% salt content, 2% salt content, and 5% salt content did have the shortest, longer and then the longest germination times, respectively and then growing the shoots in a solution of 0% salt content, 2% salt content, and 5% salt content did have the most growth, less growth and the least growth respectively on a day-by-day basis from the seed’s germination as measured by height for the five days after germination when seeds germinate within a reasonable range defined as within the first 7 days. This supports the hypothesis. However, some seeds did not germinate at all as they did not germinate in the first 7 days and were omitted from the conclusion statement, as due to biological uncertainty, it would be incorrect to consider this in our evaluation of whether the hypothesis is supported by the results.
3.1.2 Conclusion Explanation
We obtained a result that supported the hypothesis. This is in accord with former experiments and the results thereby obtained in a study by Mujeeb-ur-Rahman, Umed Ali Soomro, Mohammad Zahoor-ul-Haq and Shereen Gul of PCSIR Laboratories in 2008. This is most probably by means of the same mechanism that was outlined in the Background Information/Theory section of this report (1.1.3) and it widely accepted in scientific circles. The standard deviation or the measure of how the data was spread found roughly similar statistical deviation and this was most apparent for the 2% solution suggesting that genetic variability is at its greatest when germinating and growing in the 2% solution. Furthermore, it was apparent that the 0% solution was by far the healthiest in each and every case. On one of the days there some extra water taken in however this does not seem to have affected the results in a statistically significant way.
Evaluating Procedures
3.2.1 Evaluation
The data has a high level of reliability due to the fact that few anomalous measurements were recorded suggesting that in fact all statistically significant variables were controlled for apart from maybe the biological uncertainty. One of the few quantitative measurements that was made that seemed out of place was on Day 12 when some water may have leaking and onto the Petri dishes and thus the germinating wheat seeds during a rainstorm with an average growth on average 0.5 cms higher on that day than on any other. All seeds some to have been affected equally in spite of this. There were few qualitative observations that were anomalous apart from perhaps the mould growing in the 5% solution as this would seem unlike the characteristic behaviour of mould and it is not apparent why the healthy seeds were not thus affected however one possibility is that the species of mould that was growing on the unhealthy seeds in the 5% solution may have picked up on some biological signal or the other healthy plants may have had some adaptation that may have prevented the mould getting a foothold in their Petri dishes in agreement with standard evolutionary theory with survival of the fittest.
3.2.2 Weaknesses and limitations of the experiment
One of the major drawbacks of the experiment is that it lacks ecological validity in that perhaps it may have been more realistic for the seeds to have been germinated and grown in potting mix as opposed to on the paper towels also due to the fact that there may have residual chemicals remaining in the paper towel from the bleaching, most likely mild acids and tannins that may have affected germination however this was not apparent in the results. Moreover, seeds in the 5% solution may not have had a water concentration of 5% the whole time due to tendency of salt to form crystals and be absorbed into fibrous material and thus some of the salt may have been trapped in the paper towel and may not have contributed to the solution. This effect may have manifested itself in the 2% solution but to a lesser degree as it would seems that this effect is logarithmically correlated to salt concentration. It would lead to a lower salt concentration in the Petri dishes and thus for the seeds. This effect is hard to control for but may have been less pronounce in real seed germination potting mix as when the seeds put out their roots the stored salt would be released. In addition, not controlling for the weather may have had all sorts of unusual effects on the wheat seeds. A recommendation for preventing this would be to artificially mimic as many elements of their ideal natural environment. The weakness in determining when the seeds had actually germinated was that it was difficult to tell when the shoots actually came out. This could be better determined if they were checked more regularly say every half a day to see if germination had taken place. This would lead to more precise measurements of germination times thereby leading to more precise results which can aid in evaluating the value of the results. The seeds that were used in this experiment may have had individual genetic component differences which may have affected the outcome of the experiment. If all the seeds were specially grown so that they all had exactly the same genetic components then this would offer far better results.
3.2.3 Significance of weaknesses on experimental results
It does not seem that the weaknesses had any real noticeable effect on the results as the results seem to all support the hypothesis. However this may simply be due to the random effects of chaos theory which may be leading up to see causality where there is none due to all the random effects of factors which have not been controlled which on their own are not statically significant but together have affected the outcome of the experiment. It would not seem though that this is a likely situation. Further empirical testing of the reliability and further replication of these results is required and to be expected before the acceptance of any theory and hypothesis model.
3.3 Improvements to the experiment
Some of the improvements to the experiment have been proposed in weaknesses and limitations of the experiment (3.2.2). Further experimentation should be also undertaken in a lab setting as this would allow easier access to result, experimental setup and control of variables.
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