Question 22N.2.HL.TZ0.a
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.2.HL.TZ0.a |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | State | Question number | a | Adapted from | N/A |
Common shrews (Sorex araneus) are small mammals found in Northern Europe. Their diet includes insects, slugs, spiders, worms and amphibians. They do not hibernate in winter because their bodies are too small to store sufficient fat reserves.
[Source: [Shrew], n.d. [image online] Available at: https://www.pxfuel.com/en/free-photo-jslkw [Accessed 29 October 2021].]
To study brain size in shrews, researchers anesthetize them, X-ray their skulls and measure the height of the braincase (BCH) where the brain is located. The graph shows the relationship between BCH and the brain mass of individual adult shrews.
[Source: adapted from Lá zaro, J., Hertel, M., LaPoint, S., Wikelski, M., Stiehler, M. and Dechmann, D.K.N., 2018.
Journal of Experimental Biology 221. http://doi.org/10.1242/jeb.166595.]
State the relationship between BCH and brain mass of shrews.
[1]
positive correlation/the greater the BCH the greater the brain mass;
No mark for ‘positive relationship’ or for directly proportional
Most candidate described the relationship shown on the graph as a positive correlation. Some referred to it incorrectly as directly proportional, but that would be revealed by data points along a straight line on the graph. The term 'positive relationship' is vague and should be discouraged.
