Which of the following statements is/are correct?
I. Baker's yeast, Saccharomyces cerevisiae, is used to ferment the dough used for making bread.
II. Industrial-scale production often involves growing microbes in large vessels called fermentors.
III. Municipal wastewater is commonly referred to as sewage.
IV. Sewage needs to be treated in Sewage Treatment Plants (STPs) to reduce its pollution levels.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → I, II, III and IV
The four statements come from three parts of the chapter: microbes in household products, in industry and in sewage treatment.
Statement I: Baker’s yeast, Saccharomyces cerevisiae, is used to ferment the dough used for making bread. — True. Bread dough is fermented using baker’s yeast, Saccharomyces cerevisiae.
Statement II: Industrial-scale production often involves growing microbes in large vessels called fermentors. — True. Production on an industrial scale needs microbes to be grown in very large vessels called fermentors.
Statement III: Municipal wastewater is commonly referred to as sewage. — True. The municipal waste water of towns and cities, whose major component is human excreta, is called sewage.
Statement IV: Sewage needs to be treated in Sewage Treatment Plants (STPs) to reduce its pollution levels. — True. Sewage has a lot of organic matter and many pathogenic microbes, so before disposal it is treated in sewage treatment plants to make it less polluting.
All four statements are correct.
NCERT Extract:
Microbes in Household Products – “… Similarly the dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae).”
Microbes in Industrial Products – “Even in industry, microbes are used to synthesise a number of products valuable to human beings. Beverages and antibiotics are some examples. Production on an industrial scale, requires growing microbes in very large vessels called fermentors ….”
Microbes in Sewage Treatment – “… A major component of this waste water is human excreta. This municipal waste-water is also called sewage. It contains large amounts of organic matter and microbes. Many of which are pathogenic. … Before disposal, hence, sewage is treated in sewage treatment plants (STPs) to make it less polluting.”