3.4.1.4.1 Sources of bacterial contamination Quiz: AQA Food Preparation and Nutrition, Unit 3

The 20 questions

1. Which of these is a source of bacterial contamination in a kitchen?

   • Dried herbs stored in a sealed jar on a shelf
   • Plain flour kept in a dry tin
   • Raw poultry and its juices
   • Refined sugar kept in an airtight container

2. Which source of bacterial contamination is named in the spec as coming from other food?

   • Sunlight falling on food stored on a sunny kitchen windowsill during the warm part of the day
   • Steam from the kettle rising in the kitchen and settling on food stored near the cooker
   • Gentle heat from an oven door that is left slightly open while food is cooking inside
   • Other contaminated foods, including raw meat, poultry, eggs, seafood and vegetables

3. A cook handles raw eggs and then cuts bread without washing their hands. What is the source?

   • The flour, which has been denatured by the proteins in the raw egg
   • The knife, which is made from steel that naturally produces bacteria
   • The person cooking, who carries bacteria from the raw eggs to the bread
   • The bread, which contains enzymes that react with the egg on contact during mixing

4. Which pests are named as a possible source of contamination in a kitchen?

   • Bees visiting the fruit bowl on the kitchen table
   • Earthworms that are found in unwashed salad leaves
   • Garden birds feeding on the crumbs on the windowsill
   • Flies, rodents and cockroaches

5. Why should waste food and rubbish be kept in closed bins?

   • Waste attracts pests and harbours bacteria that can spread to food
   • Waste contains fat that emulsifies with cleaning products used nearby
   • Waste contains starch that gelatinises onto clean kitchen surfaces
   • Waste produces steam that softens the kitchen surfaces over time

6. Which surface is a source of bacterial contamination if it is not cleaned?

   • Ceramic plates stored upside down in a clean rack
   • Glass jars that are kept sealed and dry on a shelf
   • Chopping boards and work surfaces
   • Stainless steel that has been dried thoroughly after washing

7. What does cross-contamination mean in food safety?

   • Bacteria passing from one food or surface to another food
   • Two foods containing the same enzyme being cooked in the same pan
   • Two different proteins denaturing at the same temperature in a pan
   • A food being cooked at two different temperatures in one oven

8. Why are raw and cooked foods stored separately?

   • To stop protein from denaturing in cold storage conditions and losing its texture
   • To stop fat from separating out of the food during chilling and pooling in the container
   • To stop bacteria from raw foods spreading to foods that will not be cooked again
   • To stop starch from gelatinising in the fridge over time and turning the food sticky

9. Which situation gives the highest risk of contamination from pests?

   • Food frozen solid in a freezer in a well-kept kitchen
   • Food left uncovered in an open kitchen where waste is kept nearby
   • Food sealed in a fridge with waste bins kept outside the back door
   • Food stored in sealed tins on a high shelf in a clean room

10. Which of these is a source of bacteria found on raw vegetables?

    • Dextrinised sugar that forms on the outside of the vegetable skin
    • Emulsified oil that forms within the vegetable skin during growth
    • Soil and unwashed surfaces where they grew or were handled
    • Gelatinised starch that forms inside the vegetable cells during growth

11. A customer touches a food display with unwashed hands. Which contamination source is this?

    • The people handling the food
    • The pests that live in the storage room
    • The waste food and rubbish in the bin nearby
    • The work surfaces and equipment on the counter

12. Which two raw foods are named as bacterial sources in the spec?

    • Rice and pasta
    • Sugar and honey
    • Meat and eggs
    • Bread and cheese

13. Why are work surfaces and equipment a risk after raw meat has been prepared on them?

    • Raw meat leaves a sugar film that caramelises under the next heat
    • Raw meat leaves a layer of fat that emulsifies into the next food
    • Raw meat leaves starch that gelatinises when it touches warm water in the sink
    • Bacteria from the raw meat can stay on them and transfer to other foods

14. Why can vegetables grown in soil be a source of bacteria?

    • Soil contains enzymes that denature the protein in the vegetable
    • Soil contains fat that emulsifies with the juices inside the vegetable
    • Soil contains sugar that caramelises on the surface of the vegetable skin
    • Soil can carry bacteria onto the vegetables during growing and harvesting

15. Which of these is an example of waste food acting as a bacterial source?

    • Sealed packets of dried pasta kept in a cupboard
    • Frozen peas stored in the freezer for several weeks
    • Food scraps left in an open bin in the kitchen
    • Clean tinned fruit stored on a high shelf in the pantry

16. A chef uses the same knife to cut raw chicken and then ripe tomatoes without washing it. Which route of contamination is this?

    • Emulsification caused by oil that has been left on the knife
    • Enzymic browning caused by the steel of the knife
    • Gelatinisation caused by the tomato juice on the blade
    • Cross-contamination from equipment used on raw food

17. Why is the spec's list of contamination sources important for a food business?

    • It shows that bacteria come only from the air, so food only needs covering
    • It shows the many routes by which bacteria can enter food, so each one needs control
    • It shows that only raw meat is ever a risk, so other foods need no checks
    • It shows that bacteria are always killed by the cooking process itself

18. Which two groups of contamination sources are linked to people and equipment?

    • The pests, and the waste food left in the bins
    • The people cooking, and the work surfaces and equipment
    • The enzymes in the food, and the vitamins lost during cooking
    • The raising agents in the mix, and the flour used in baking

19. A cook wipes a surface with a dirty cloth after cutting raw eggs. What is the risk?

    • Bacteria from the eggs are spread to the surface and to other food
    • Protein from the eggs denatures and dries on the surface and hardens
    • Starch from the eggs gelatinises onto the surface and sticks there
    • Fat from the eggs emulsifies with the cloth and leaves a film

20. Which of these is a contamination source from other food?

    • Dry food that has been sealed in a glass jar on a shelf
    • Raw meat that drips onto ready-to-eat food stored below it
    • Cold food kept below 5°C in a fridge with its lid on
    • Hot food kept above 63°C in a hot-holding cabinet during service

Related quizzes

• Growth conditions for microorganisms and enzymes Quiz · 3.4.1.1.1 · 20 questions
• High risk foods and control of microorganism growth Quiz · 3.4.1.1.2 · 20 questions
• Control of enzymic action in food Quiz · 3.4.1.1.3 · 20 questions
• Signs of food spoilage: enzymic action, mould and yeast Quiz · 3.4.1.2 · 20 questions
• Microorganisms in food production Quiz · 3.4.1.3 · 20 questions
• Main food poisoning bacteria Quiz · 3.4.1.4.2 · 20 questions
• Control and general symptoms of food poisoning Quiz · 3.4.1.4.3 · 20 questions
• Buying and storing food safely Quiz · 3.4.2.1 · 20 questions
• Preparing, cooking and serving food safely Quiz · 3.4.2.2 · 20 questions
• Protein: biological value, complementation and alternatives Quiz · 3.2.1.1 · 20 questions