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The World of Microbes - Friendly Microorganisms in Food and Industry

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Microorganisms are used for various beneficial purposes such as the preparation of curd, bread, and cake.

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The bacterium LactobacillusLactobacillus promotes the formation of curd by multiplying in milk and converting it into curd.

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Yeast reproduces rapidly and produces carbon dioxide (CO2CO_2) during respiration. The bubbles of gas fill the dough and increase its volume, making bread and pastries fluffy.

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Fermentation is the process of conversion of sugar into alcohol by the action of yeast. This was discovered by Louis Pasteur in 18571857.

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Microbes are used for the large-scale production of alcohol, wine, and acetic acid (CH3COOHCH_3COOH).

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Antibiotics are medicines produced from bacteria and fungi that kill or stop the growth of disease-causing microorganisms. Examples include Streptomycin and Tetracycline.

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Some bacteria like RhizobiumRhizobium and blue-green algae are able to fix nitrogen from the atmosphere to enrich the soil with nitrogen and increase its fertility (N2N_2 to Nitrogenous compounds).

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Microorganisms decompose dead organic waste of plants and animals, converting them into simple substances (nutrients) and cleaning the environment.

📐Formulae

C6H12O6→Yeast2C2H5OH+2CO2+EnergyC_6H_{12}O_6 \xrightarrow{\text{Yeast}} 2C_2H_5OH + 2CO_2 + \text{Energy}

CH3CH2OH+O2→AcetobacterCH3COOH+H2OCH_3CH_2OH + O_2 \xrightarrow{\text{Acetobacter}} CH_3COOH + H_2O

N2→Nitrogen Fixing BacteriaNitrates (NO3−)N_2 \xrightarrow{\text{Nitrogen Fixing Bacteria}} \text{Nitrates (NO}_3^- \text{)}

💡Examples

Problem 1:

Explain the role of yeast in the baking industry and why the dough rises.

Solution:

In the baking industry, yeast is added to flour dough. Yeast undergoes anaerobic respiration, converting sugars into CO2CO_2 and ethanol (C2H5OHC_2H_5OH).

Explanation:

The equation for this process is C6H12O6→2C2H5OH+2CO2C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2. The bubbles of CO2CO_2 gas released get trapped in the dough, causing it to swell or 'rise,' making the bread light and spongy.

Problem 2:

How do leguminous plants help in maintaining soil fertility?

Solution:

Leguminous plants (like peas and beans) have a symbiotic relationship with RhizobiumRhizobium bacteria located in their root nodules.

Explanation:

These bacteria take atmospheric nitrogen (N2N_2) and convert it into soluble nitrogenous compounds like nitrates (NO3−NO_3^-), which plants can easily absorb. This process reduces the need for chemical fertilizers.

Problem 3:

What is the commercial method of producing vinegar?

Solution:

Vinegar is produced by the fermentation of alcohol using a bacterium called AcetobacterAcetobacter.

Explanation:

First, yeast converts sugar into ethanol (C2H5OHC_2H_5OH). Then, AcetobacterAcetobacter bacteria convert the ethanol into acetic acid (CH3COOHCH_3COOH) in the presence of oxygen (O2O_2), which is the main component of vinegar.