3.3.2.5.3 Biological raising agents: yeast Quiz: AQA Food Preparation and Nutrition, Unit 2

The 20 questions

1. What biological raising agent is used in bread making?

   • Bicarbonate of soda
   • Yeast
   • Whisked egg white
   • Cream of tartar

2. What gas does yeast produce during fermentation that raises bread?

   • Methane
   • Carbon dioxide
   • Oxygen
   • Ammonia

3. What does yeast ferment in a bread dough?

   • Sugars in the dough, releasing carbon dioxide and alcohol
   • Salt in the dough, releasing starch and oil as the dough rises
   • Protein in the dough, releasing sugar and water into the mix
   • Gluten in the flour, releasing steam and fat into the dough

4. Why is a little sugar added to a bread dough made with yeast?

   • It denatures the yeast so the dough sets firm and does not rise
   • It gelatinises in the dough to thicken it before the first rise
   • It feeds the yeast, which speeds fermentation and gas production
   • It emulsifies with the fat to give the dough a smooth, even texture

5. Why is a bread dough kept in a warm place to prove?

   • Warmth caramelises the sugar so the dough turns brown before baking
   • Warmth denatures the gluten so the dough becomes soft and runny
   • Warmth emulsifies the fat so the dough stays moist in the tin
   • Warmth helps the yeast ferment faster, producing gas that raises the dough

6. What happens if a bread dough is put into a very hot oven before the yeast has risen it?

   • The starch caramelises inside, so the dough becomes sweet and brown
   • The gluten becomes more elastic, so the dough rises more evenly overall
   • The yeast is killed, so gas production stops and the dough rises less
   • The yeast becomes more active, so the dough rises rapidly and collapses

7. Which product in the spec is raised using yeast?

   • Meringue
   • Scones
   • Choux pastry
   • Bread

8. Why is yeast dough kneaded thoroughly?

   • To spread the yeast evenly and develop gluten that can trap the gas
   • To denature the yeast so that it stops fermenting in the bowl
   • To caramelise the sugars so that the dough browns more during baking
   • To dissolve the yeast completely into the fat in the dough

9. What temperature range suits yeast activity in a dough?

   • Freezing, below 0°C
   • Warm, around 25°C to 30°C
   • Boiling, at 100°C
   • A hot oven, around 200°C, which is the best temperature for the yeast to work and produce its gas

10. Why does adding too much salt to a bread dough slow the rise?

    • Salt slows yeast activity, so less gas is produced
    • Salt gelatinises the starch, so the dough thickens too early
    • Salt denatures the gluten, so the dough becomes soft and sticky
    • Salt caramelises the sugars, so the dough darkens and sets early

11. What does yeast need to be active in a dough?

    • Boiling water, a high fat level and salt
    • Dry heat, oxygen and a high level of sugar
    • Strong acid, cold conditions and darkness
    • Moisture, food and warmth

12. Why does a yeast dough rise more slowly in a cool kitchen?

    • Yeast ferments more slowly at low temperatures, so gas forms more slowly
    • Cold air dissolves the gas, so less carbon dioxide reaches the dough
    • Cold air denatures the flour protein, which stops the yeast from feeding
    • Cold air caramelises the sugars, which stops the gluten from forming

13. What is proving in bread making?

    • Heating the dough quickly to kill the yeast before it is baked
    • Leaving the shaped dough to rise so that yeast produces gas and the dough expands
    • Pressing the dough flat to remove all the gas before it is shaped
    • Testing the flour for its protein content before the dough is mixed

14. A baker wants a more flavoursome bread. Which change most helps flavour through yeast action?

    • A slower rise at a cooler temperature for longer, which builds more flavour
    • A high salt level, which increases the yeast's gas production greatly
    • A large amount of baking powder, which adds a sharp, lingering taste
    • A very fast rise in a hot oven, which removes all of the flavour

15. What effect does yeast fermentation have on the flavour of bread?

    • It emulsifies the fat, which gives bread a greasy and heavy taste
    • It produces flavour compounds that give bread a characteristic taste
    • It removes all the flavour from the dough by boiling it in the tin
    • It caramelises the flour, which gives bread a burnt and bitter taste

16. Why is yeast dough sometimes knocked back after its first rise?

    • To release some large gas bubbles and spread the yeast before shaping
    • To denature the gluten so the dough can be stretched very thin
    • To dissolve the sugar fully so that the dough becomes sweeter in taste
    • To melt the fat and emulsify it with the water in the dough

17. Why does a yeast dough rise faster when more yeast is added?

    • More yeast cells emulsify the fat, so the dough holds more gas
    • More yeast cells caramelise the sugar, so the dough browns faster
    • More yeast cells ferment more sugar, producing carbon dioxide faster
    • More yeast cells denature the gluten, so the dough becomes softer and more runny

18. Which factor stops yeast producing gas during baking?

    • The dough becoming too wet, because yeast only works in dry dough
    • The gluten forming, because yeast cannot work in an elastic dough
    • The sugar caramelising, because yeast needs an unburnt supply of sugar
    • Its death at high oven temperatures once the dough is hot enough

19. Why is a yeast-raised loaf often left to cool on a wire rack after baking?

    • So the sugar can caramelise further on the outside of the loaf
    • So steam escapes and the crust stays crisp rather than soggy
    • So the gluten can set and the crumb becomes denser throughout
    • So the yeast can finish fermenting in the cool air around the loaf

20. Which statement compares yeast and bicarbonate of soda as raising agents correctly?

    • Both raise only when frozen, which keeps the gas trapped inside the dough
    • Both raise by releasing oxygen gas that comes from the flour in the mix
    • Yeast raises instantly through a chemical reaction, while bicarbonate raises slowly through fermentation
    • Yeast raises through biological fermentation over time, while bicarbonate raises quickly through a chemical reaction

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