I'm writing up an experiment on "The effect of light on the rate of locomotion in blowfly larvae" and I'm pretty sure I'm not making any sense in question 2.
It's asked the effect of differing light wavelengths on rate. I know I probably shouldn't be doing this this late otherwise hopefully I wouldn't be so confused but can someone look at this and see if I'm making sense? Doesn't help that I don't know what the rate is supposed to be of. There is a table of our results at the bottom of the document.
Our results are awful btw, just to warn you
Thanks for any enlightenment in advance.
Investigate the effect of light on the rate of locomotion in blowfly larvae
1) The results we obtained did not fit what was expected from the experiment as the graph should show that as light increases rate should also increase, how our results showed that as light intensity increased rate decreased. We would expect that as the light intensity increased maggots would spend less time in the side of the petri disk that was subject to the full intensity of the light, in comparison with the shaded cardboard side as maggots should gravitate towards their known dark living conditions as part of a photo taxis. We carried out the experiment at 3 different light intensities 14.2 at 7cm, 5.8 at 17cm and 4.5 at 7cm. The table below shows our rate results.
Distance from petri disk Light intensity Rate
7cm 14.2 3.43
17cm 5.8 7.11
22cm 4.5 7.37
As seen the rate at which the maggots moved into the dark, shaded cardboard covered section of the petri disk decreased as light intensity increased.
2 )The graph showing rate against light wavelength shows that there is another factor influencing rate.The wavelengths emitted by the different coloured filters (Green, yellow, red and blue) suggest that the maggots prefer the certain conditions, and respond differently to different wavelengths than others. The results showed that the rate in which maggots left the coloured filters were highest in the blue and green filters which suggests that the maggots did not favour these wavelengths as much as the red and yellow coloured filters. The maggots also spent an average time of 48 seconds in the yellow filter which was the second highest period of time spent in the filter covered area of the petri dish before leaving which suggested that this wavelength was favoured. However we did also receive some conflicting results which questioned the reliability of our data. The maggots spent the longest period of time in the green filter averaging 88 seconds, although the rate in which they left the filter was the highest. This may be down to any anomalous results, as we only carried out one repeat of the experiment which left the results fairly unreliable.
3) Our conclusion from our results states otherwise, however our conclusion should show that the greater the light intensity the greater the rate in which the maggots move into the darker, cardboard covered area of the petri dish.
4) Limitations would be that sometimes the maggots were placed in different locations on the petri dish and therefore some would move all the way along the side of the dish and others would start from the middle. If some maggots were placed nearer to the shaded side of the disk they would notice this and immediately start moving towards this side, however others took longer to notice this. Some maggots also managed to escape and had to be placed back inside the petri dish. Finally, maggots become tired quickly some more than others which could
5) The limitations affect the validity of our conclusion as the times we noted down that the maggots spent in and out of the light could be affected by the fact some maggots noticed the change in light straight away and others didn’t have this same chance as they were placed on the other side of the petri dish. Furthermore the fact that some maggots escaped meant that the time taken to put the maggot back in the dish, and in a different position could have added extra time to the time the maggot supposedly spent in the light.
6) These limitations could be improved and resolved firstly by placing the maggots in an agreed position at the start of each experiment when the timer was started. This should allow the results to be far more reliable. Furthermore,
Filter Time spent in Light(s) Time spent in Dark(s) Time spent in Light(s) Time spent in Dark(s) Average(s) Dark Average Light (s)
Green 7.32 32.78 48.50 145
Yellow 28.41 49.96 11.8 48.01
Red 16.06 11.22 12.32 32.62
Blue 44.53 51.5 21.34 28.24