| Date | November 2009 | Marks available | 1 | Reference code | 09N.3.SL.TZ0.1 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | State | Question number | 1 | Adapted from | N/A |
Question
Zinc (Zn) is an important dietary nutrient. More than 200 enzymes that are dependent on zinc have been identified. One consequence of zinc deficiency is suppression of appetite, due to reduced sensitivity to tastes and smells. A recent study compared the presence of zinc in tissue and fluid samples collected from 15 patients with anorexia nervosa to that from 15 control patients. The results are shown in the graphs below.
Compare the zinc content of scalp hair of the control group with that of the anorexia nervosa group.
Discuss whether whole blood zinc content of 6 μg g–1 would indicate that a person has anorexia nervosa.
Discuss whether dietary zinc supplementation would be an effective treatment for anorexia nervosa.
Zinc is a mineral. Distinguish between a mineral and a vitamin.
State the body mass index (BMI) below which a person is considered to be underweight.
Markscheme
mean zinc content higher in control group;
control group more variable;
overlap between two groups / highest of anorexia nervosa group equals mean of control group;
(data suggest this is) probable / could be symptom;
other conditions could lead to low zinc;
6 μg g–1 is within the lower range of “normal”;
zinc supplementation is necessary for insufficient dietary intake / improvement in below normal intake would be resolved;
improved appetite may result;
low zinc may be effect not cause of anorexia nervosa / other causes of anorexia;
minerals are inorganic while vitamins are organic;
minerals tend to be in ionic elemental form/small molecules while vitamins tend to be larger molecules;
(below a BMI of) 18.5kg m-2 (units needed)
Examiners report
Many candidates answered the comparison well, but many others simply stated numbers instead of comparing.
This question was generally answered well. Many candidates realised that this value could be an indicator of anorexia because it was very low, but there was a control person who had this same value.
Generally answered well.
Many candidates failed to answer this question correctly.
Many candidates failed to give the units for BMI.
