Lesson 3.4.1.3

3.4.1.3 Microorganisms in food production Quiz: AQA Food Preparation and Nutrition, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.4.1.3, Microorganisms in food production: 20 multiple choice questions for the AQA GCSE Food Preparation and Nutrition (8585), Unit 3: Food safety, written with Revision Ninja.

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The 20 questions

  1. Which mould is used to make blue cheese?

    • Aspergillus oryzae
    • Saccharomyces cerevisiae
    • Lactobacillus bulgaricus
    • Penicillium roqueforti

  2. Which micro-organism is used to raise bread?

    • Yeast
    • Penicillium roqueforti
    • Streptococcus thermophilus
    • Campylobacter jejuni

  3. Which micro-organisms are used to make yoghurt?

    • Staphylococcus aureus that makes the milk sour and firm as it stands
    • Listeria cultures that set the milk protein into a solid, sliceable mass
    • Lactic acid bacteria such as Lactobacillus bulgaricus and Streptococcus thermophilus
    • Salmonella strains that thicken milk into a firm and stable gel

  4. Why does the lactic acid made by bacteria help milk set into yoghurt?

    • It emulsifies the milk fat into a stable and solid layer on top
    • It lowers the pH of the milk, which causes its proteins to coagulate
    • It raises the pH of the milk, which makes its proteins dissolve away
    • It caramelises the milk sugars into a thick, firm and brown gel

  5. What is the main role of bacteria in cheese production?

    • Producing steam that raises the curd into a light, airy texture
    • Producing fat that emulsifies the curd into a smooth, spreadable paste
    • Producing starch that gelatinises the curd into a firm, cut gel
    • Producing lactic acid from lactose, which sets and flavours the cheese

  6. What is the role of blue mould in blue cheese?

    • It grows through the cheese to give veining and a sharp flavour
    • It produces alcohol that evaporates to leave a dry, crumbly texture
    • It makes the rind waxy and waterproof for long-term storage
    • It lowers the fat content of the curd during the ripening period

  7. Why is yeast used in bread rather than blue mould?

    • Blue mould forms veins that make the bread sharp and crumbly in texture
    • Yeast ferments sugars to produce carbon dioxide that raises the dough
    • Blue mould sets the dough protein and stops the bread from rising
    • Yeast produces a sour acid that thickens the dough into a firm gel

  8. Which of these is a micro-organism used in food production rather than a contaminant?

    • Listeria on cold smoked fish
    • Lactobacillus in yoghurt
    • E. coli in undercooked mince
    • Salmonella in raw eggs

  9. Why are cheese makers careful about hygiene even when they use beneficial micro-organisms?

    • Beneficial bacteria are destroyed by cleaning, so cleaning must be avoided
    • Hygiene is needed only to keep the cheese cold, not to stop contamination
    • Unwanted micro-organisms could spoil or contaminate the cheese
    • Beneficial micro-organisms turn harmful when they touch steel surfaces

  10. Which of these products is made by fermenting a food with micro-organisms and is also a yeast-raised product from the spec?

    • Choux bun
    • Pizza base
    • Sponge cake
    • Scone

  11. Which micro-organism is used to make a sourdough bread's distinctive flavour?

    • Listeria from a soft cheese added to the starter at the start
    • Campylobacter from raw chicken added to the dough by mistake
    • Blue mould spores added to the flour mix before kneading
    • Wild yeasts and lactic acid bacteria in a fermented starter

  12. What is a benefit of micro-organisms in dairy foods?

    • They remove the protein from the milk so that it becomes a clear and thin liquid
    • They increase the amount of fat in the finished dairy product
    • They create flavour and texture in cheese and yoghurt during fermentation
    • They make the milk safe by killing all the harmful bacteria within it

  13. Why is a yoghurt starter culture added to warm milk?

    • To introduce starch that gelatinises and turns the milk into a gel
    • To introduce enzymes that caramelise the milk sugar into a syrup
    • To introduce fat that emulsifies with the milk into a thick cream
    • To introduce bacteria that ferment lactose and thicken the milk

  14. What is the main sugar in milk that bacteria ferment in yoghurt?

    • Maltose
    • Fructose
    • Sucrose
    • Lactose

  15. Why must the moulds in blue cheese be grown in a controlled way?

    • To produce the veining and flavour without letting spoilage moulds take hold
    • To make the cheese sweet by caramelising its sugars during ripening
    • To remove all the fat so that the cheese becomes lower in calories
    • To cause the cheese to set firm by denaturing its milk protein

  16. Why do dairy producers often use pasteurised milk for yoghurt making?

    • To destroy harmful bacteria so that the starter cultures are not competing with pathogens
    • To emulsify the milk fat so that the yoghurt is thick and cream-like before any culture is added
    • To destroy enzymes so that the milk is thinner and the yoghurt sets more slowly in the pot
    • To caramelise the milk sugar so that the finished yoghurt tastes naturally sweet and mellow

  17. Which micro-organism is responsible for producing alcohol and carbon dioxide in bread dough?

    • Staphylococcus aureus
    • Penicillium roqueforti
    • Yeast
    • Lactobacillus bulgaricus

  18. What is a starter culture in cheese making?

    • A measured group of beneficial bacteria added to milk to start fermentation
    • A raw meat extract added to the milk to flavour the curd
    • A pure sugar added to the milk to feed the milk protein
    • A solution of starch added to the milk to thicken it before cooking

  19. Which two products in the spec use micro-organisms to raise or set them?

    • Bread and yoghurt
    • Choux pastry and roux
    • Shortbread and custard
    • Mayonnaise and meringue

  20. What is a key difference between beneficial and harmful bacteria in food?

    • Beneficial bacteria only grow in frozen food, while harmful bacteria grow in hot food
    • Beneficial bacteria are deliberately added and controlled, while harmful bacteria are unwanted contaminants
    • Beneficial bacteria are never found in food, while harmful bacteria are always present in it
    • Beneficial bacteria produce toxins, while harmful bacteria produce flavour compounds in food

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