Biology · 2014 · May · Paper 3 · SL · TZ2 · Markscheme

M14/4/BIOLO/SP3/ENG/TZ2/XX/M 14 pages MARKSCHEME May 2014 BIOLOGY Standard Level Paper 3 – 2 – M14/4/BIOLO/SP3/ENG/TZ2/XX/M Option A — Human nutrition and health 1. (a) 0.5 kg (units required) [1] (b) increase / positive trend / towards gain in body mass [1] (c) is effective at maintaining mass as final mass is equal to initial mass; only group not showing weight/mass re-gain (after 26 weeks); shows weight loss / maintenance (with fluctuations) in early weeks; last weeks (from week 18) show positive trend; [2 max] (d) excess carbohydrates converted/stored as fat/lipids; source of obesity / gain in weight; may increase risk of diabetes / other related health risk factor; other nutrients may be deficient; [2 max] 2. (a) (i) chemical substance found in foods that is used in the human body [1] (ii) (amino acid that) can be synthesized by the body (from other nutrients) [1] (b) (i) dairy products / (oily) fish / egg yolk / liver / other verified source [1] Do not award marks for any supplements. (ii) malignant melanoma results from repeated/prolonged exposure to UV; sunlight contains some UV; (moderate) daily exposure to sunlight stimulates skin to produce vitamin D; vitamin D may help prevent osteoporosis/rickets/weak bones/low immunity/some cancers/cardiovascular disease; risk balanced by having moderate exposure to sunlight/sunbathing at safe times/using sunblock/clothes; supplements to provide vitamin D; [3 max] 3. (a) appetite control centre in brain is stimulated by hormones/ghrelin/leptin/ PYY336/insulin; produced by pancreas/small intestine after eating; (produced) by adipose tissue in response to fat storage; stretch receptors in stomach send message to brain; makes the person feel they have eaten enough; [3 max] (b) food miles are a measure of distance between production and consumption; high food miles increases transport; causes air pollution / traffic congestion / increases greenhouse gas emissions; local foods not found all year round, so a balanced diet might not be achieved with locally available foods; buying local products supports local economy; local foods are fresh/do not require preservatives; [3 max]