Question 20N.2.SL.TZ0.1d.ii
| Date | November 2020 | Marks available | [Maximum mark: 2] | Reference code | 20N.2.SL.TZ0.1d.ii |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Suggest | Question number | d.ii | Adapted from | N/A |
Using all of the data so far, suggest whether exposure to freezing temperatures in the four cities is supported as a reason for the differences in HCN production in T. repens.
[2]
a. cities with more days without snow cover have positive correlation between distance from city center and HCN / vice versa for Montreal;
b. fewer plants with HCN within cities that have more days without snow cover/have more exposure to freezing temperatures / converse for Montreal which has fewer days without snow cover;
c. HCN is 0.2 (or less) HCN in cities that have more days without snow cover proportion whereas city with fewer days/Montreal it is 0.5/more than 0.4;
d. in Toronto cyanogenic and non-cyanogenic plants show little difference in herbivory;
e. support for hypothesis/exposure to freezing temperatures as reason.
Do not accept ‘Yes’ unqualified as an answer, but accept it if supported by reasoning.
Many candidates found this to be another difficult question. There was a lot of data to consider and as in (c) it was necessary to take into account whether differences were likely to have been significant. In the histogram showing the amount of cold experienced, the large error bars show that only differences between Montreal and the other three cities are great enough to be considered reliable. When combined with data for the proportion of plants with HCN in each city, it was clear that there was support for exposure to cold as a reason.
