| Date | May 2013 | Marks available | 2 | Reference code | 13M.3.HL.TZ1.4 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Deduce | Question number | 4 | Adapted from | N/A |
Question
European robins (Erithacus rubecula) migrate South in the autumn (fall) and North in the spring. They orient their direction of flight using the local magnetic field, which they detect through magnetoreceptors in the upper beak. The orientation of the birds in a captive environment was studied in spring and autumn, which are the times of year when the birds normally migrate. The response of the birds to green light, red light and total darkness was investigated. Triangles on the edge of circles indicate the mean direction flown by individual birds while the arrows indicate the overall mean direction of flight.
Identify the season and light conditions which result in the strongest northerly direction flown by the robins.
Season:
Light conditions:
Distinguish between the effect of red light and green light on the behaviour of the robins in spring and autumn (fall).
Based on the results of these experiments, suggest one possible conclusion that could be drawn regarding the effect of red light on the behaviour of robins.
Using the data in the diagram, deduce with a reason, whether European robins migrate during the daytime or at night.
Scientists anesthetized the beaks of some robins in order to deactivate the magnetoreceptors. Predict how this would affect their orientation in red light.
Markscheme
spring, green light
Both required for [1].
a. in green light birds migrate North in spring but South in autumn;
b. in red light birds orientate (North) West in both autumn and spring;
a. in red light birds do not migrate in the normal pattern/direction;
b. red light disorientates the birds/interferes with the functioning of magnetoreceptors;
c. red light has (almost) the same effect as total darkness / birds do not see in red light;
a. during daytime;
b. direction of migration is not normal/wrong orientation in darkness;
a. no effect;
b. may become (even) more random;
Examiners report
This option was very popular and candidates tended to score well on it.
Almost all candidates read the diagrams correctly for the 1 mark.
This option was very popular and candidates tended to score well on it.
Most candidates were able to correctly distinguish between the effects of red and green light on robin behaviour.
This option was very popular and candidates tended to score well on it.
Many candidates repeated their response to section (b) in this question and did not get the 1 mark.
This option was very popular and candidates tended to score well on it.
Almost all correctly deduced that the robins migrated in daylight but only some could clearly explain why for the second mark.
This option was very popular and candidates tended to score well on it.
Most candidates were able to get at the 1 mark for this.
