Q45 — Drosophila Color Preference and Circadian Activity

Theoretical 1 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license

Drosophila melanogaster fruit flies have complex innate color preferences depending on time of day. Flies were kept for 6 days in tubes with plastic colored filters creating red, blue, and green bands, at constant temperature/humidity with a 12h light/12h dark cycle. Color preference was measured by the number of flies in each color zone, alongside their motor activity.

Figure 1. Experimental setup showing randomized filter order in the test tubes. Figure 1. An example of the randomized order of filters.

Figure 2. Fly color preference and motor activity over 6 days, ZT 0 = start of daylight, ZT 12 = lights off. Figure 2. Fruit fly color preferences and motor activity during 6 days. ZT 0 — the start of daylight, ZT 12 — the point of lights being turned off. Panel 1: color preferences of flies. Panel 2: top curve — proportion of flies in different color bands; bottom curve — mobile activity of flies.

Using the information and figures, determine whether the following statements are true or false:

A. The maximum values of green color preference is related to with the late morning and early evening motor activity.

B. In the middle of the day, flies occur with equal frequency in green and red bands.

C. Based on the given data individual fruit flies tend to remain in one colour band during the night (from ZT 12 to ZT 0).

D. In the dark, flies are randomly distributed between color bands and occur with equal frequency in all bands.

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Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)