HL2 Biology: E.3a Innate Behavior

DBQ p. 326- Chemotaxis in Woodlice
1. One method to lure the woodlice into the arms of the syringe would be to put another woodlice into one of the arms of the syringe. To keep the second woodlouse already in the arm to not move to the already present woodlouse in the syringe, a small net-like structure can be attached at the very end of one of the arms of the syringe. That way, the woodlouse in the syringe can move into the arm, while the other remains put at the end of the arm. Another method would be to change the independent variable to food scent (put food-scented air into the syringe), but instead of testing chemotaxis, this would test foraging behavior.

2. Generally, in all species, more woodlice moved into the arms of the scented syringe. Furthermore, O. asellus had the highest number of lice moving into both scented and unscented arms of the apparatus (148 and 69 respectively), while A. vulgare had the second highest number for the scented arm and the lowest number for the unscented arm (115 and 55 respectively), and  P. scaber had the lowest number for the scented arm and the second lowest for the unscented arm (101 and 62 respectively).

3. The woodlice must have chemoreceptors because they were able to distinguish between scented and unscented environments, and more were attracted to the scent of the members of their own species.

4. (a) Many subjects moved to the scented arm of the apparatus because they were most likely attracted to the scent of other members of the species, which makes evolutionary sense because finding other members of one’s species is absolutely necessary to reproducing.
(b) Some subjects moved to the unscented arm perhaps because they assumed there was no competition for resources (e.g. food) in that area due to the lack of other woodlice.