Microbiology Multiple Choice Questions on “Industrial Uses of Yeasts”.
1. Which among the following are not used as raw materials for alcohol production?
A. corn
B. molasses
C. whey
D. grapes
Answer: C
Clarification: Corn, molasses, sugar beets, potatoes, and grapes are some of the common raw materials employed throughout the world for alcohol fermentation.
2. The organism used for alcohol fermentation should have a high tolerance for alcohol.
A. True
B. False
Answer: A
Clarification: It is imperative that the culture be one that grows vigorously and has a high tolerance for alcohol as well as a capacity for producing a large yield of alcohol.
3. What is the pH required for the production of baker’s yeast?
A. 1 to 2
B. 4 to 5
C. 7 to 8
D. 10 to 12
Answer: B
Clarification: In the manufacture of baker’s yeast, the medium is adjusted to an acid pH of 4 to 5, which helps retard bacterial growth.
4. The leavening or rising of dough is due to which of the following gases?
A. oxygen
B. carbon dioxide
C. hydrogen
D. sulphur dioxide
Answer: B
Clarification: The carbon dioxide produced during the fermentation by baker’s yeast is responsible for the leavening or rising of the dough.
5. Which of the following instrument is used for the recovery of yeast cells?
A. fermenter
B. centrifuge
C. filter press
D. mash storage
Answer: C
Clarification: The cells are finally recovered on a filter press, small amounts of vegetable oil are added as a plasticizer, and then this mass of cells is molded into blocks.
6. Which of the following product is used as a food condiment?
A. Baker’s yeast
B. Ethanol
C. Wine
D. Soy sauce
Answer: D
Clarification: Soy Sauce is produced by the yeast Saccharomyces rouxii and is used as a food condiment.
7. Which of the following yeast can be used to produce microbial protein?
A. Saccharomyces cerevisiae
B. Candida milleri
C. Eremothecium ashbyi
D. Candida utilis
Answer: D
Clarification: Candida utilis is yeast used for producing microbial protein which is used as an animal food supplement (single-cell protein) from paper-pulp waste.
8. The medium for production of Baker’s yeast contains only molasses and inoculum.
A. True
B. False
Answer: B
Clarification: In the manufacture of baker’s yeast the “stock” strain is inoculated into a medium that frequently contains molasses and corn-steep liquor.
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