Question 20N.2.SL.TZ0.1a
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.2.SL.TZ0.1a |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Comment | Question number | a | Adapted from | N/A |
A study was conducted to look at the short-term effects of a change in diet on the risk of disease in young adults. The table shows data on the habitual diet of the participants as well as the study diet followed for two weeks.
[Source: Horowitz, J.F., Ortega, J.F., Hinko, A., Li, M., Nelson, R.K. and Mora-Rodriguez, R.,
2018. Changes in markers for cardio-metabolic disease risk after only 1-2 weeks of a high saturated fat diet in
overweight adults. PLoS ONE, 13(6), e0198372.]
Comment on the total energy content of the two diets.
[1]
a. energy is not changed (between the two diets);
b. study diet slightly lower in energy than habitual diet (but means/SD overlap);
c. spread of values show more variation for habitual diet / higher SD in habitual;
Considering that all students must complete an Individual investigation as part of their Biology course, few understood the significance of the uncertainties shown in the first table or the overlap of the standard deviations in the graph in part d. Only the better candidates were able to say that the energy was extremely similar in both diets. A surprising number could not calculate a percentage change in part c.
In part b, the command term was ‘distinguish’ which means that only differences were looked for. Similarly in d(i), ‘compare’ means that only similarities were needed. If both were required, the command term is ‘compare and contrast’.
In d, few could state that there was no significant difference in the two curves due to the overlap of the error bars. Most knew that the beta cells of the pancreas secrete insulin, although a surprising number thought that they were produced by the red blood cells. In e, many gained two marks for linking saturated fats to cholesterol and its consequence.
