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Explore the role of yeast in biotechnology, from fermentation to industrial processes like baking and brewing. Learn about yeast's ability to convert sugars and create alcohol, and the importance of controlled conditions for efficient production.
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BIOTECHNOLOGY (a) Living Factories
1. What type of micro-organism is yeast? A fungus
2. What does yeast feed on? Sugar
3. What type of asexual reproduction does yeast show? Budding
4. Name 2 industrial processes which depend on yeast. • Baking • Brewing
5. What makes the bread dough rise? Carbon dioxide bubbles given off by the yeast.
6. Why do beer and wine making depend on yeast? The yeast makes the alcohol.
7. What name is used to describe the action of yeast cells on sugar in the absence of oxygen ? Fermentation
8 Fermentation can be shown in the word equation below: Glucose + ………. ………… + ……… + energy yeast alcohol CO2
9. When anaerobic respiration happens in plants and yeast, what 2 bi-products are produced? • Alcohol • Carbon dioxide
10. In commercial brewing, what 3 conditions must be carefully controlled for efficient production ? • Temperature • Oxygen supply • Concentration of glucose
11. In commercial brewing why is it important that unwanted microbes are kept out ? They might spoil the quality and flavour of the beer.
12. What 5 ingredients are added to the vat to make beer ? • Yeast • Malt • Hops • Sugar • water
13. In batch processing, why is it a disadvantage that the yeast has to be filtered out of the beer at the end of the process ? Production is only possible in batches and is not a continuous process.
14. What does the brewing industry use as a source of food for the yeast? Barley
15. What is the main problem with using barley to feed the yeast? Yeast cannot feed on the carbohydrate stored in barley because it is in the form of starch.
16. What must be done to the barley before the yeast can feed on it? The barley grains must be allowed to germinate.
17. What does germination do to the carbohydrate in the barley? The starch is broken down into sugar which the yeast can use.
18. Name the sugar formed in the barley. Maltose
What name is given to the process by which the starch in the barley is changed into a sugar? 19. Malting
20. Name the enzyme in the barley seeds which converts starch to sugar. Amylase
21. Name 2 industrial processes which depend on the action of bacteria. • Cheese making • Yoghurt production
22. What process is the souring of milk an example of? Fermentation
23. Name the sugar found in milk. Lactose
24. Why must the lab bench be thoroughly cleaned and equipment sterilised before working with microbes? To kill any bacteria which may be present at the start of the experiment.
25. Why must the petri dishes be autoclaved (sterilised) at the end of the experiment? To kill any harmful bacteria which may have been cultured by mistake.
26. How can bacteria and fungi be destroyed ? • Drying out • pH changes • Disinfectants • Very high temperatures
27. How might resistant fungal spores be destroyed? • Temperatures above 121oC • High pressure Answer:
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