Biology

Microorganisms in Food Production

1,086 Questions

Microorganisms play a vital role in food production through processes like fermentation and bioprocessing. Questions on this topic cover the use of yeast, bacteria, and industrial microbiology. These concepts are important for science sections in various competitive exams.

Alcoholic fermentationDairy beverage productionIndustrial ethanol preparationCitric acid productionBiodigester temperature

Microorganisms in Food Production Questions

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

The most common substrate used in distilleries for the production of ethanol is

  1. Molasses

  2. Corn meal

  3. Soya meal

  4. Ground gram
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Molasses are used commonly in distilleries for ethanol production. Saccharomyces cerevisiae is an industrial yeast possessing most of the desirable fermentation characteristics like fast growth and fermentation rate, osmo-tolerance, high ethanol tolerance, ability to ferment molasses, and to ferment at elevated temperatures etc.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

The fruit juices turn bitter in taste if they are kept in open place for sometime, because of

  1. Bacteria of the atmosphere react with the juice.

  2. Fermentation of the juice by yeast.

  3. Some internal factors.

  4. All the above three statements are correct.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Raw fruit juice is usually a strongly acidic solution, containing from 10 to 25 percent soluble sugars. Its acidity and high sugar concentration make it an unfavourable medium for the growth of bacteria but highly suitable for yeasts and moulds. Raw fruit juice naturally contains many yeasts, moulds, and bacteria, derived from the surface of the fruit. Normally, the yeast used in alcoholic fermentation is a strain of the species Saccharomyces cerevisiae

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

The bread is soft and porous when the yeast cells are mixed in the lump of wheat flour because

  1. Yeast produce benzoic acid.
  2. Evolution of $CO _{2}$makes the bread spongy.

  3. Yeast is soft and flour also becomes soft.

  4. Yeast produces acetic acid and alcohol which give softness to the bread.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When yeast is added to a mixture of dough, a fermentation process begins as the yeast eats the sugars and releases carbon dioxide gas. The yeast absorbs the oxygen in the dough as it begins a reproduction of cells, dividing the single yeast cell into two cells, which then become four, and redividing continuously into increasingly larger numbers of cells. Trapped in the dough, the yeast cells produce carbon dioxide resulting in the rising of the dough until it reaches a point in size to be burst, reducing it back into its original shape to begin the rising process again. This second rising is faster due to the abundance of cells now present from multiplying continuously.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Vitamin $B _{12}$ is produced directly during the course of fermentation by

  1. Ashbya gossypii

  2. Rhizopus stolonifer

  3. Saccharomyces cerevisiae

  4. Propionibacteria
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It has been demonstrated that Propionibacteria species has the highest potential to accumulate vitamin B$ _{12}$ intracellularly. Propionibacterium shermanii and Propionibacterium freudenreichii are most widely used. Propionibacteria produce vitamin B$ _{12}$ intracellularly and excrete mainly propionic acid and acetic acid extracellularly. All Propionibacterium strains employed for vitamin B$ _{12}$ production are microaerophilic and produce vitamin B$ _{12}$ in high yields only under very low oxygen concentrations.

Thus, the correct answer is option D. 

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

In cheese manufacture, the micro-organisms are used for

  1. The souring of milk only

  2. The ripening only

  3. Both A and B

  4. Development of resistance to spoilage
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The curdling step in cheese making relies on lactic acid bacteria. These bacteria are able to ferment the carbohydrates found in the milk, releasing lactic acid in the process. The lactic acid causes the proteins dissolved in the milk to precipitate, or come out of solution. When the proteins precipitate, they pull out the fats as well. What you are left with is similar to the sour milk from the introduction: the liquid whey filled with many solid chunks of protein and fat, called curds.

Yeasts and molds are used in some cheeses to provide the characteristic colours and flavours of some cheese varieties. Torula yeast is used in the smear for the ripening of brick and limberger cheese. Examples of molds include Penicillium camemberti in camembert and brie, and Penicillium roqueforti in blue cheeses.
Thus, the correct answer is option C.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Conversion of sugar into alcohol during fermentation is due to the direct action of

  1. Temperature

  2. Microorganism

  3. Zymase

  4. Concentration of sugar solution
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The overall process of fermentation is to convert glucose sugar (C$ _6$H$ _{12}$O$ _6$) to alcohol (CH$ _3$CH$ _2$OH) and carbon dioxide gas (CO$ _2$). The reactions within the yeast to make this happen are very complex but the overall process is as follows: 

C$ _6$H$ _{12}$O$ _6$ ==> 2(CH$ _3$CH$ _2$OH) + 2(CO$ _2$) 
Sugar ==> Alcohol + Carbon dioxide gas. 
The most important type of fermentation is alcoholic fermentation, in which the action of zymase secreted by yeast converts simple sugars, such as glucose and fructose, into ethyl alcohol and carbon dioxide.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

First fermented acid is

  1. Gluconic acid

  2. Lactic acid

  3. Fumaric acid

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lactobacillus bacteria have the ability to convert sugars into lactic acid. The Lactobacillus strain is so named because it was first studied in milk ferments. These bacteria readily use lactose or other sugars and convert them quickly and easily to lactic acid.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Which one of the following is used in industrial preparation of ethanol?

  1. Lactobacillus

  2. Azotobacter

  3. Penicillium

  4. Saccharomyces
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Yeast are simple unicellular organisms belonging to the Kingdom Fungi. The alcoholic fermentation is conducted by yeast of the genus Saccharomyces. The two common species involved are S. cerevisiae and S. bayanus. Saccharomyces converts the glucose, fructose and sucrose found in grape must and juice into ethanol via the process of fermentation. In fermentation, an organic compound, in this case acetaldehyde, serves as terminal electron acceptor. This leads to the production of ethanol.
Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Vitamin ${B} _{12}$ is formed during fermentation of

  1. Ashbya gossypii

  2. Rhizopus stolonifer

  3. Propionibacteria

  4. Saccharomyces cerevisiae
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Vitamin B$ _{12}$ is one of the important vitamins of B complex group. It is also known as cobalamin or cobamide. 
Direct fermentation employing Bacillus megaterium, Propionibacterium freudenreichii, Propionibacterium shermanii and Pseudomonas is used for commercial production of vitamin B$ _{12}$. 
Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Saccharomyces cerevisiae is used in the formation of

  1. Ethanol

  2. Methanol

  3. Acetic acid

  4. Antibiotics
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

S. cerevisiae is known for its role in food production. It is the critical component in the fermentation process that converts sugar into ethyl alcohol (ethanol), an ingredient shared in beer, wine and distilled beverages. It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. 

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Which of the following is used to manufacture ethanol from starch?

  1. Penicillin

  2. Saccharomyces

  3. Azotobactor

  4. Lactobacillus
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

S. cerevisiae is known for its role in food production. It is the critical component in the fermentation process that converts sugar into ethyl alcohol (ethanol), an ingredient shared in beer, wine and distilled beverages. It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. 

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

During the formation of bread, it becomes porous due to release of CO$ _{2}$ by the action of

  1. Yeast

  2. Bacteria

  3. Virus

  4. Protozoan
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a bread dough, where the oxygen supply is limited, the yeast can only partially breakdown the sugar. Alcohol and carbon dioxide are produced in this process known as alcoholic fermentation. The carbon dioxide produced in these reactions causes the dough to rise, and the alcohol produced mostly evaporates from the dough during the baking process. During fermentation, each yeast cell forms a centre around which carbon dioxide bubbles form. Thousands of tiny bubbles, each surrounded by a thin film of gluten form cells inside the dough piece. The increase in dough size occurs as these cells fill with gas.

Thus, the correct answer is option A.

Multiple choice biology biotechnology and genetic engineering stds and infertility gm crops biotechnology

Which one is not used in the production of yogurt?

  1. Streptococcus lactis

  2. Streptococcus thermophilous

  3. Lactobacillus bulgaris

  4. Acetobacter aceti
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yogurt is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as yogurt cultures. Fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and its characteristic tang. Some representative strains of yogurt cultures are Streptococcus lactis, S. cremoris, S. thermophilus, Lactobacillus bulgaricus, L. acidophilus, and L. plantarum.