1
Complete the statements below by picking the correct term from the choices and then write the final, complete sentences.
Answers:
a. The procedure where milk proteins form thick clumps (______) happens because of lactic acid.
coagulation
Complete sentence: The procedure where milk proteins form thick clumps (coagulation) happens because of lactic acid.
b. Harmful bacteria in the digestive system, like ______, are destroyed by probiotics.
clostridium
Complete sentence: Harmful bacteria in the digestive system, like clostridium, are destroyed by probiotics.
c. The chemical name for the substance we call ______ is vinegar.
acetic acid
Complete sentence: The chemical name for the substance we call acetic acid is vinegar.
d. Minerals that are used to add calcium and iron to diets are made from ______ acid.
gluconic
Complete sentence: Minerals that are used to add calcium and iron to diets are made from gluconic acid.
Key Terms Explained:
- Coagulation: Process where proteins clump together, important in cheese and yogurt making
- Clostridium: Harmful bacteria that can cause digestive issues
- Acetic acid: CH₃COOH, the main component of vinegar
- Gluconic acid: Used to make mineral supplements more absorbable
- Lactobacilli: Beneficial bacteria found in probiotics and fermented foods
2
Connect the items in the 'A' list with their correct description in the 'B' list.
Answer:
Please complete this matching question from your textbook.
Common Microbiology Terms for Matching:
- Fermentation: Metabolic process that converts sugar to acids, gases, or alcohol
- Probiotics: Live beneficial bacteria for digestive health
- Pasteurization: Heat treatment to kill harmful microbes in food
- Antibiotics: Substances that inhibit or destroy microorganisms
- Enzymes: Biological catalysts that speed up chemical reactions
- Bio-remediation: Using microbes to clean up environmental pollutants
3
Answer the following questions.
Answers:
(A) What kinds of energy sources (fuels) can we make using microbes? Why should we start using these fuels more often?
Methane Gas (Biogas)
Production: Created when microbes break down organic waste (from cities, farms, factories) in anaerobic conditions (without oxygen).
Process: Anaerobic digestion by methanogenic bacteria.
Source: Agricultural waste, sewage, landfill waste.
Ethanol (Bioethanol)
Production: Made when yeast (Saccharomyces) ferments molasses or other sugar sources.
Properties: Clean-burning fuel with minimal smoke production.
Source: Sugarcane, corn, other carbohydrate-rich crops.
Hydrogen Gas
Production: Released during bio-photolysis of water by photosynthetic bacteria.
Properties: Considered the future fuel - high energy content, only produces water when burned.
Process: Photo-reduction by cyanobacteria or algae.
Why Use These Biofuels More?
- Conserve Non-renewable Resources: Reduce dependence on finite fossil fuels (coal, petroleum)
- Reduce Air Pollution: Biofuels produce fewer pollutants and greenhouse gases
- Carbon Neutral: Plants absorb CO₂ during growth, balancing emissions from burning
- Waste Utilization: Convert agricultural/industrial waste into valuable energy
- Energy Security: Reduce reliance on imported fossil fuels
(B) How can we clean up the oil slicks that have polluted rivers and oceans?
Microbial Oil Spill Cleanup
- Problem: Petroleum oil spills from accidents are toxic to marine life and difficult to remove mechanically.
- Solution: Use hydrocarbon-degrading bacteria like Pseudomonas spp. and Alcanovorax borkumensis.
- Process: These bacteria naturally break down oil (hydrocarbons) through bioremediation.
- Mechanism: Bacteria oxidize hydrocarbons using oxygen, producing CO₂ and water as harmless end products.
- Term: These microbes are called Hydrocarbon-Clastic Bacteria (HCB).
- Advantages: More effective and environmentally friendly than mechanical methods.
(C) How can soil that has been made infertile by acid rain be fixed and used for growing things again?
Soil Remediation from Acid Rain
- Problem: Acid rain and mining waste contain sulfuric acid that damages soil, corrodes structures, and makes land infertile.
- Solution: Use acidophilic (acid-loving) bacteria that use sulfuric acid as an energy source.
- Key Bacteria: Acidophillium spp. and Acidobacillus ferroxidens.
- Process: These microbes metabolize sulfuric acid, reducing soil acidity.
- Mechanism: Bacteria oxidize sulfur compounds, converting harmful acids to less toxic forms.
- Result: Soil pH is restored, making it suitable for plant growth again.
(D) Explain the high value of using natural pesticides (bio-pesticides) in farming that avoids chemicals.
Bio-pesticides in Organic Farming
- Application: Microbial inoculants are sprayed on seeds or crops after fermentation.
- Example: Mixtures containing Azotobacter and artificial nitrogenase for nitrogen fixation.
- Environmental Benefit: Prevents soil pollution caused by chemical fertilizers and pesticides.
- Soil Cleanup: Microbes can degrade harmful pesticide residues already in soil.
- Genetic Engineering: Bacterial/fungal toxins that kill pests can be inserted into plants.
- Variety: Bacteria, fungi, and viruses can all serve as effective bio-pesticides.
- Known Bio-pesticide: Spinosad - a fermentation byproduct widely used in organic farming.
(E) What are the main reasons why products containing beneficial bacteria (probiotics) are becoming increasingly popular?
The Rise of Probiotics
- Definition: Milk-based foods containing active beneficial bacteria like Lactobacillus.
- Gut Balance: Maintain healthy gut flora by increasing beneficial microbes and reducing harmful ones like Clostridium.
- Colonization: Help establish beneficial microbial communities in the digestive system.
- Health Benefits:
- Strengthen immune system
- Reduce harmful effects of metabolic toxins
- Control growth of pathogenic microorganisms
- Antibiotic Recovery: Reactivate beneficial microbes suppressed by antibiotic treatments.
- Medical Uses: Treat severe diarrhea and used in poultry farming to promote health.
(F) How do bread and other food items made with baker's yeast become rich in nutrients?
Nutritional Enrichment through Yeast
- Basic Process: Bread dough made from cereal flour mixed with Saccharomyces cerevisiae (baker's yeast), water, and salt.
- Fermentation: Yeast ferments carbohydrates, converting sugars to CO₂ and ethanol.
- Leavening: CO₂ gas causes dough to rise, creating soft, spongy texture.
- Yeast Forms: Compressed yeast in commercial bakeries; dry granular form for home use.
- Nutritional Content: Industrial yeast is rich in:
- Carbohydrates and proteins
- Fats and essential vitamins (B-complex)
- Minerals (zinc, selenium, iron)
- Result: Bread and yeast-based products become nutrient-dense due to yeast's nutritional profile.
(G) What necessary actions should be taken for household garbage to break down properly?
Proper Household Waste Management
- Rural Areas: Domestic sewage released into ground or biogas plants.
- Urban Areas: Sewage must go to treatment plants where microbes process it.
- Source Separation: Households should separate waste into dry and wet categories.
- Dry Waste: Collected in bins and transported to landfill sites.
- Wet Waste: Converted into organic compost through microbial decomposition.
- Composting: Natural breakdown by microbes produces nutrient-rich fertilizer.
- Importance: Proper segregation enhances recycling and reduces landfill burden.
(H) Why is it crucial to put a total stop to the use of plastic bags?
The Case Against Plastic Bags
- Pollution: Contaminate both water bodies and land ecosystems.
- Blockage: Careless disposal clogs water drainage systems.
- Non-renewable Source: Made from polypropylene derived from petroleum (finite resource).
- Non-biodegradable: Do not break down naturally; persist for hundreds of years.
- Recycling Difficulty: Complex and expensive to recycle effectively.
- Wildlife Hazard: Harm marine animals through ingestion and entanglement.
- Environmental Impact: Release toxic chemicals as they slowly degrade.
- Solution: Complete ban necessary to protect ecosystems and conserve resources.
4
Complete the following conceptual diagram (Mind Map).
Answer:
Please complete this mind map from your textbook.
Key Concepts for Microbiology Mind Map:
- Central Theme: Applications of Microbiology
- Main Branches:
- Food Production (fermentation, dairy, baking)
- Medicine (antibiotics, vaccines, probiotics)
- Agriculture (bio-fertilizers, bio-pesticides)
- Environment (bioremediation, waste treatment)
- Industry (enzymes, chemicals, biofuels)
- Key Microorganisms: Bacteria, Fungi, Yeast, Algae
- Processes: Fermentation, Decomposition, Nitrogen Fixation
- Products: Antibiotics, Enzymes, Organic Acids, Gases
5
Provide a scientific reason.
Answers:
(A) The use of genetically changed microbe strains has increased a lot in factory-based microbiology.
Reason: During large-scale production (especially in dairy), strict sterilization is required as viruses (bacteriophages) can attack production bacteria. Genetically modified strains are developed to be phage-resistant. Additionally, mutant strains are artificially created to:
- Eliminate unnecessary production steps
- Remove requirements for specific growth factors
- Increase product yield and efficiency
- Enhance resistance to contamination
This makes industrial processes more efficient and cost-effective.
(B) Enzymes created using microbial processes are mixed into washing powders and liquids (detergents).
Reason: Microbial enzymes offer significant advantages over chemical catalysts:
- Efficiency at Low Conditions: Work effectively at low temperatures, low pH, and low pressure
- Energy Saving: Reduce energy requirements for heating water
- Cost-effective: No need for expensive corrosion-resistant equipment
- Cleaning Power: Specifically break down protein, fat, and carbohydrate stains
- Environmental: Biodegradable and eco-friendly compared to chemical alternatives
This allows effective cleaning even in cold water, saving energy.
(C) Microbial enzymes are chosen over chemical catalysts in chemical manufacturing.
Reason: Microbial enzymes provide multiple advantages in industrial applications:
- Specificity: Catalyze only specific reactions, minimizing unwanted byproducts
- Mild Conditions: Operate at ambient temperature, pressure, and pH
- Energy Efficiency: Significant energy savings compared to chemical processes
- Purification Cost: Reduced purification costs due to fewer side products
- Reusability: Often can be recovered and reused multiple times
- Waste Reduction: Generate less industrial waste
- Environmental: Biodegradable and sustainable
These factors make microbial enzymes economically and environmentally preferable.
6-7
Complete the following conceptual diagrams.
Answers:
Please complete questions 6-7 (conceptual diagrams) from your textbook.
Xanthan Gum Uses (Question 6):
- Food Industry: Thickener, stabilizer in sauces, dressings, ice cream
- Oil Industry: Drilling fluid additive for viscosity control
- Cosmetics: Thickening agent in lotions, creams, toothpaste
- Pharmaceuticals: Controlled drug release, tablet binder
- Agriculture: Pesticide and fertilizer suspension agent
- Production: Produced by fermentation of Xanthomonas campestris
Environmental Applications of Microbes (Question 7):
- Waste Treatment: Sewage treatment, organic waste decomposition
- Bioremediation: Oil spill cleanup, heavy metal removal
- Composting: Converting organic waste to fertilizer
- Biofuels: Production of methane, ethanol, hydrogen
- Pollution Control: Degrading pesticides, plastic alternatives
- Soil Health: Nitrogen fixation, improving soil fertility
8
Answer the following questions.
Answers:
(A) What do microbes do in the process of making compost?
- Collection: Organic waste is dumped into large pits in open spaces away from residential areas.
- Layering: Covered with soil, wood shavings, dead leaves, and specific chemicals; bioreactors may be added.
- Microbial Action: Naturally occurring soil microbes break down organic material through decomposition.
- Sealing: When pits are full, they are sealed with wet soil paste to create anaerobic conditions.
- Time: After several days/weeks, high-quality compost is formed.
- Recovery: Landfill sites can be reused after compost collection.
- Key Microbes: Bacteria and fungi that decompose cellulose, proteins, and other organic compounds.
(B) What are the benefits of mixing ethanol with petrol (gasoline) and diesel?
- Energy Content: Ethanol has about 33% less energy than pure gasoline but offers other advantages.
- Common Use: Most often blended with gasoline as a bio-fuel additive (E10, E85).
- Environmental Benefits:
- Lower carbon monoxide emissions than pure gasoline
- Reduced greenhouse gas emissions
- Biodegradable and less toxic than fossil fuels
- Economic Benefits:
- Domestic production from crops supports local agriculture
- Reduces dependence on imported oil
- Creates rural employment opportunities
- Engine Performance: Higher octane rating improves engine performance.
(C) Which plants are grown to get fuel?
Bio-fuel Crops: Plants specifically cultivated for fuel production:
Corn (Maize)
Sugarcane
Palm Oil
Jatropha
Soybean
Canola (Rapeseed)
Cottonseed
Sunflower
Wheat
Sorghum
Sugar Beet
Cassava
Types of Biofuels:
- First Generation: Food crops (corn, sugarcane) - direct competition with food supply
- Second Generation: Non-food crops & agricultural waste (jatropha, crop residues)
- Third Generation: Algae-based fuels - highest yield potential
(D) What fuels are created from natural materials (biomass)?
- Carbon Cycle: Plants absorb CO₂ during growth; same CO₂ released when burned, making it carbon-neutral.
- Solid Biofuels:
- Wood chips and pellets
- Agricultural residues (straw, husks)
- Used for heating and electricity generation
- Liquid Biofuels (Transportation):
- Biodiesel: From vegetable oils, animal fats
- Ethanol: From fermentation of corn, sugarcane
- Biobutanol: Higher energy content than ethanol
- Gaseous Biofuels:
- Biogas: Methane from anaerobic digestion
- Syngas: From gasification of biomass
- Sources: Wood waste, energy crops, municipal solid waste, agricultural residues.
(E) Why does bread become soft and airy (spongy)?
- Basic Ingredients: Cereal flour mixed with Saccharomyces cerevisiae, water, salt, etc.
- Fermentation Process: Yeast metabolizes carbohydrates (sugars) in the dough.
- Gas Production: Fermentation produces CO₂ (carbon dioxide) and ethanol as byproducts.
- Dough Rising: CO₂ gas gets trapped in the gluten network, causing dough to expand and rise.
- Baking Effect: During baking, heat causes further expansion of gas bubbles.
- Final Texture: After baking, the set structure retains the air pockets, creating soft, spongy texture.
- Additional Factors:
- Gluten development provides elastic structure
- Proper kneading distributes yeast and develops gluten
- Adequate proofing time allows proper gas formation