| Date | May 2015 | Marks available | 2 | Reference code | 15M.3.HL.TZ2.4 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Distinguish | Question number | 4 | Adapted from | N/A |
Question
Honey bees (Apis mellifera) were fed with sucrose solution only or with low doses of ethanol in sucrose solution to examine how a slightly intoxicated state could affect their behaviour. Individual behaviour involves walking and grooming while social behaviour includes contact of antennae between bees to show recognition (antennation) and asking other bees for food when hungry (begging). The graphs show individual and social behaviour changes observed in successive five minute intervals two hours after honey bees were fed sucrose solution either with or without ethanol.
State the percentage of time the honey bees engaged in begging during the first five minute interval.
Bees fed with ethanol: .....................%
Bees fed without ethanol: .....................%
Describe the trends in antennation for honey bees fed with ethanol and without ethanol.
Distinguish between the times spent walking and grooming for honey bees fed with ethanol and without ethanol.
Evaluate the hypothesis that ethanol affects the social behaviour of honey bees.
Markscheme
bees fed with ethanol:
5.9 (%); (allow answers in the range of 5.8 (%) to 6.0 (%))
bees fed without ethanol:
1.3 (%); (allow answers in the range of 1.2 (%) to 1.4 (%))
(both needed)
a. without alcohol (antennation starts at a high level and) decreases with time;
b. with alcohol, the value (starts low and) very slowly increases;
c. the values of both groups become very similar with time;
a. (time spent) walking is greater in bees without alcohol (than alcohol);
b. (time spent) grooming is greater with alcohol (than without alcohol);
c. the end point difference is greater in walking;
d. (time spent) walking increases whereas grooming decreases for both groups of bees;
a. (hypothesis is supported as) alcohol decreases antennation at the start of the experiment;
b. (hypothesis is supported as) alcohol increases begging at the start;
c. begging time is more variable/less significant differences with alcohol (so less clear than in antennation);
d. (hypothesis is supported as) the effect of alcohol on social behaviors becomes less distinguishable over time (with the effect of sucrose) / OWTTE;
Examiners report
The vast majority of candidates stated the percentages correctly, but there were some answers out of range and some others in which candidates inverted the values.
Most described the trends in antennation correctly, but some only stated values without saying that they were decreasing or increasing or described minor changes for each interval without mentioning the general trend.
Most described the trends in antennation correctly, but some only stated values without saying that they were decreasing or increasing or described minor changes for each interval without mentioning the general trend. Similar answers were presented for the differences between walking and grooming.
The evaluation of the hypothesis was more difficult for many who failed to mention that the effect was more noticeable at the beginning of the observation period or did not read that the components of social behaviour were antennation and begging.
