Questions
3–4 questions per exam
Difficulty
Easy
Importance
High yield for board exams
Overview
Microbes in Human Welfare explores the diverse roles microorganisms play in food processing, industrial manufacturing, and environmental management. Understanding the symbiotic relationship between human society and microbial activity is essential for scoring in CBSE biology board exams. Aspirants must focus on the specific names of microbes and their respective products or enzymes to secure full marks.
Microbes in Food Processing
Microbes are utilized to transform raw ingredients into value-added food products through fermentation. This process not only preserves food but also enhances nutritional value, such as increasing Vitamin B12 content.
- Lactobacillus converts milk to curd by producing lactic acid
- Saccharomyces cerevisiae is known as Baker's yeast
- Dough for idli/dosa is fermented by bacteria releasing CO2
- Swiss cheese texture is due to large holes from CO2 production by Propionibacterium sharmanii
- Roquefort cheese is ripened by Penicillium roqueforti
Microbes in Industrial Products
Large-scale industrial production relies on fermentation in bioreactors to produce chemicals, enzymes, and bioactive molecules. Precision in memorizing the scientific names of these microbes is critical for answering objective questions.
- Aspergillus niger produces Citric acid
- Acetobacter aceti produces Acetic acid
- Clostridium butylicum produces Butyric acid
- Lactobacillus produces Lactic acid
- Saccharomyces cerevisiae produces Ethanol
- Streptokinase acts as a clot buster produced by Streptococcus
Sewage Treatment Processes
Sewage treatment utilizes heterotrophic microbes naturally present in wastewater to reduce organic pollutants. The process is divided into primary, secondary (biological), and tertiary stages to ensure water safety before discharge.
- Primary treatment is physical removal of floating debris and grit
- BOD (Biochemical Oxygen Demand) measures organic matter indirectly
- Secondary treatment uses aerobic microbes forming flocs
- Activated sludge contains aerobic bacteria and fungal filaments
- Anaerobic sludge digesters break down remaining bacteria and fungi
- Biogas is a mixture of gases like methane, H2S, and CO2
Exam Tip
Create a table with three columns: 'Microbe Name', 'Category', and 'Product/Function' and memorize it verbatim to handle any matching or MCQ question.
Common Mistakes
- Confusing the specific microbe with the product it produces, especially in industrial production lists.
- Incorrectly identifying BOD as a measure of dissolved oxygen rather than the oxygen required to oxidize organic matter.
- Misspelling scientific names, which often leads to mark deductions in board exams.
More Revision Notes
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