O-LevelBiologyHuman Nutrition5090/21 · May/June 2021 · Q610 Marks

Yoghurt is a milk product.

(a)Outline the role of microorganisms in the process of yoghurt production.[5]
(b)The diagram shows a food label from a pot of yoghurt. contents nutritional values in 100 g of yoghurt energy 344 kJ fat 4.5g total carbohydrates 5.5g sugar 5.5g fibre 0.0g protein 4.2g salt 0.1 g calcium 0.125g water 81% Yoghurt can contribute to a balanced diet but adult humans cannot survive by eating only yoghurt. Explain this statement using the information on the label.[5]

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Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[1] heating / pasteurisation at start of process or after fermentation ;
[1] denaturation of milk protein / kill unwanted bacteria;
[1] starter culture / bacteria ;
[1] Lactobacillus (bulgaricus) / Streptococcus (thermophiles) ;
[1] fermentation / anaerobic respiration ;
[1] warm temperature;
[1] lactose / milk sugar;
[1] decreases pH ;
[1] lactic acid produced ;
[1] coagulation / thickening;
[1] (yoghurt contributes to a balanced diet) carbohydrates for energy ;
[1] proteins for growth / repair;
[1] water for chemical reactions / cytoplasm / transport;
[1] fats for energy / insulation;
[1] calcium for bones / prevent rickets ;
[1] (yoghurt is not suitable on its own) no + fibre + so poor bowel health / constipation ;
[1] no + iron;
[1] no + vitamin C or other named vitamin;

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