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# Aim: To observe the orientation response of fly larvae (maggots) to light. Hypothesis: Fly larvae are photophobic and tend to move from light to darkness.

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Introduction

Perception of stimuli Aim: To observe the orientation response of fly larvae (maggots) to light. Hypothesis: Fly larvae are photophobic and tend to move from light to darkness. Material: - Lamp - Bran - Tray - 100 maggots - Stopwatch Method: 1. All lights were turned off in the laboratory. 2. Some bran was scattered on a tray and half of the tray was shaded. A laboratory lamp was installed over the other half of the tray. 3. 10 maggots were placed on the light half of the tray and start the stopwatch. ...read more.

Middle

and the proportion which exhibited a positive phototaxis (26%). Null hypothesis: 50% of the fly larvae stay on the light half of the tray and 50% on the dark half. In order to confirm or reject the null hypothesis, chi-squared test was carried out. Number of groups: 2 Observed frequency (O) in group one: 1+2+2+2+5+3+1+4+4+2 = 26 Observed frequency (O) in group two: 9+8+8+8+5+7+9+6+6+8 = 74 Expected frequency (E) in group one: (26+74) /2 = 50 Expected frequency (E) in group two: (74+26) /2 = 50 Table 2: Depicting the calculated parameters for chi-squared test Group 1 (maggots in light) ...read more.

Conclusion

X2 = 23.04 is higher than the critical values at 5%, therefore, the null hypothesis can be rejected; implying that with 95% certainty the distribution of fly larvae is not even in the two regions. As comes from figure 1, approximately 3/4 of the maggots show a negative phototaxis i.e. tend to move to the darker region, while 1/4 of the maggots tend to exhibit a positive phototaxis i.e. tend to stay in the light. It could, thereby, be concluded that the result obtained holds true for the hypothesis made. ?? ?? ?? ?? 07-01-10 IB3, Katedralskolan Shiba Younus ...read more.

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