• Lactobacilli: Milk sugar (lactose) → lactic acid; curd formation, low pH inhibits pathogens; used for yogurt, buttermilk, cheese, pickles, fermented fodder & breads/wines.
• Probiotics: Foods enriched with useful microbes improve gut health & immunity.
• Rhizobium (symbiotic): Lives in legume root nodules; fixes atmospheric nitrogen to ammonia/nitrates → more plant protein; reduces chemical fertilizer need; seed-coating (inoculation) boosts yield.
• Yeast (unicellular fungus): Reproduces by budding; ferments sugars → alcohol + CO\(_2\); used in bread (spongy texture), beverages, ethanol industry; some yeasts/bacteria help in bioremediation.
• Antibiotics: Substances from microbes (bacteria/fungi) that inhibit pathogens; e.g., penicillin (from Penicillium)—historic breakthrough; use only on prescription, complete the course; avoid misuse.
• Harmful fungi: Grow on damp leather, jute, wood; spoil pickles/jams producing mycotoxins → unsafe to eat.
• Clostridium: Anaerobic rod bacteria; some cause food poisoning; form resistant endospores; need oxygen-poor conditions to grow.
• Diseases & prevention: Viruses, bacteria, protozoa, fungi cause human diseases; maintain hygiene, clean food/water, vaccinations, vector control, safe cooking, safe sexual practices, avoid needle reuse.

1) Name the bacteria that curdle milk.

Lactobacilli—convert lactose to lactic acid.

2) What lowers the pH of milk while making yogurt?

Lactic acid produced by lactobacilli.

3) Define probiotic food.

Food containing beneficial microbes that improve gut health.

4) Name the symbiotic nitrogen fixer in legumes.

Rhizobium.

5) What are root nodules?

Swollen structures on legume roots housing Rhizobium.

6) Yeast reproduces by?

Budding.

7) Write the basic fermentation products by yeast.

Alcohol (ethanol) and CO\(_2\).

8) First widely used antibiotic?

Penicillin.

9) Penicillin is obtained from which organism?

Penicillium (a fungus).

10) What are mycotoxins?

Toxic substances produced by fungi in food.

11) Clostridium grows best under which condition?

Anaerobic (low/absent oxygen).

12) What is an endospore?

A resistant spore formed by bacteria in harsh conditions.

13) Example of broad-spectrum antibiotic.

Amoxicillin / Tetracycline / Ampicillin.

14) Example of narrow-spectrum antibiotic.

Penicillin / Erythromycin / Gentamycin.

15) What is rhizobial inoculation?

Coating seeds with Rhizobium to enhance nitrogen fixation.

16) Name a bio-remediation microbe for oil spills.

Alcanivorax (bacteria).

17) Which gas makes bread spongy?

Carbon dioxide from yeast fermentation.

18) Why put oil layer on pickles?

To block air/moisture & prevent fungal growth.

19) What are pathogens?

Disease-causing microbes.

20) Who discovered penicillin’s effect?

Dr. Alexander Fleming (1928).

1) How does yogurt inhibit harmful bacteria?

Low pH due to lactic acid prevents pathogen growth.

2) Why do legumes have higher protein?

Rhizobium supplies fixed nitrogen for amino acid/protein synthesis.

3) Write one industrial use of yeast.

Ethanol production from molasses/grains.

4) Why is ethanol blended (10%) with petrol/diesel?

To reduce emissions & fossil fuel use; improve combustion.

5) Why bread is softer than chapati?

CO\(_2\) from yeast inflates dough → airy/spongy texture.

6) Give a caution while using antibiotics.

Use only on medical advice; complete full course.

7) Which microbes make pickles unsafe?

Fungi producing mycotoxins.

8) Why leather/jute spoil more in rains?

High humidity favours fungal growth.

9) Clostridium food-poisoning occurs when?

Cooked food is stored in low-oxygen, warm conditions.

10) One example of disease caused by virus.

Dengue / Influenza / Measles / Hepatitis.

11) Mode to prevent mosquito-borne diseases?

Remove stagnant water; nets; repellents; community cleanliness.

12) Why are vaccines stored safely?

To maintain potency; also for handling pathogen strains safely.

13) What is budding in yeast?

A small outgrowth develops & detaches as daughter cell.

14) Name a probiotic benefit.

Improved digestion, reduced gut infections.

15) One preventive step for fungal skin infections.

Personal hygiene; keep skin dry; avoid sharing clothes.

16) Which institute in Pune works on viruses?

National Institute of Virology (NIV).

17) Why apply salt inside pickle jars?

Salt lowers water activity, inhibiting microbes.

18) What is a broad-spectrum antibiotic?

Active against many bacterial types.

19) What is bioremediation?

Microbial cleanup of pollutants/toxins.

20) Name a microbe absorbing arsenic.

Saccharomyces cerevisiae (yeast).

1) Explain how lactobacilli turn milk to curd.

They ferment lactose to lactic acid, lowering pH; casein coagulates → thick curd; acidity suppresses harmful microbes.

2) Give two uses of lactobacilli in industry.

Manufacture of yogurt/cheese/pickles; silage (fermented fodder); souring for cocoa/cider.

3) Describe symbiosis between Rhizobium and legumes.

Bacteria fix N\(_2\) to nitrogenous compounds for plant; plant supplies carbohydrates & shelter (nodules).

4) What is seed inoculation? Benefit?

Coating seeds with Rhizobium; enhances nodulation & nitrogen supply, reduces chemical fertilizers.

5) Outline yeast fermentation in bread making.

Yeast ferments sugars → CO\(_2\) inflates gluten network; dough rises; baking sets airy crumb.

6) Why do we observe bubbles in yeast–sugar–water experiment?

Released CO\(_2\) accumulates; limewater test turns milky indicating CO\(_2\).

7) State two cautions for antibiotic use.

Never self-medicate; complete prescribed course to avoid resistance.

8) Distinguish broad- vs narrow-spectrum antibiotics with one example each.

Broad: act on many bacteria (e.g., tetracycline); Narrow: specific (e.g., penicillin).

9) How do fungi spoil pickles?

They grow on moist, exposed surfaces, produce mycotoxins making food unsafe.

10) Why rainy season favours fungal growth on leather/jute?

High humidity + spores in air → hyphae penetrate materials, weakening them.

11) Give a safety measure to prevent food poisoning at feasts.

Serve hot; avoid long storage; cover properly; maintain hygiene; rapid cooling of leftovers.

12) Mention one microbe for oil-spill cleanup & how it helps.

Alcanivorax degrades hydrocarbons, reducing oil pollution.

13) State Fleming’s observation leading to penicillin.

Bacteria-free zone around a fungal colony (Penicillium) on a plate—fungus secreted antibacterial substance.

14) Why keep clothes with naphthalene balls?

Repels insects/moths & reduces microbial growth by vapours.

15) How do pathogens spread via water & how to prevent?

Contaminated water transmits cholera/hepatitis; prevent by filtration, boiling, sanitation.

16) Why are some Clostridia dangerous despite cooking?

Endospores survive heat and can germinate later under anaerobic storage.

17) Explain why foam accumulates on dal kept long in summer.

Natural microbes ferment sugars/proteins producing gases → frothing.

18) Give one reason bread is easy to digest.

Fermentation partially breaks down complex carbs/proteins; lighter, airy structure aids digestion.

19) State two measures to prevent fungal skin diseases.

Keep skin dry; wear breathable clothes; avoid sharing towels/clothes.

20) What is the role of ethanol blending in fuels?

Reduces greenhouse emissions, increases octane, supports biofuel economy.

a) Yeast reproduces asexually by the ............. method.

Answer: budding. A small bud grows on parent yeast cell and detaches as a daughter cell.

b) Toxins of fungal origin are called ............. .

Answer: mycotoxins. These make contaminated food unsafe.

c) Leguminous plants can produce more proteins due to ............. .

Answer: rhizobium. It fixes nitrogen making amino acids for proteins.

Yogurt

Lactobacilli.

Bread

Yeast (Saccharomyces).

Root nodules of legumes

Rhizobium.

Idli/Dosa batter

Yeast & lactic acid bacteria (natural fermentation).

Spoiled potato curry

Fungi/bacteria (e.g., molds producing mycotoxins).

a) Pneumonia, diphtheria, chicken pox, cholera

Odd: Chicken pox (viral). Others are bacterial.

b) Lactobacilli, rhizobia, yeast, clostridia

Odd: Clostridia (often harmful/food poisoning). Others are generally useful.

c) Root rot, rust (tambera), rubella, mozaic

Odd: Rubella (viral human disease). Others are plant diseases.

a) Foam accumulates on dal kept long in summer.

Microbes ferment constituents releasing gases; proteins act as foaming agents → froth appears.

b) Naphthalene balls are kept with stored clothes.

Their vapours repel insects/moths and reduce microbial growth, protecting fabric.

Modes: Contact with infected person/items (towels, clothes, combs), damp skin/folds favour growth, airborne spores on wet surfaces.
Prevention: Personal hygiene; keep skin dry; breathable clothing; avoid sharing personal items; treat pets if infected; antifungal treatment as advised.

‘A’ group	‘B’ group	Match
1. Rhizobium	a. Food poisoning	→ b. Nitrogen fixation
2. Clostridium	b. Nitrogen fixation	→ a. Food poisoning
3. Penicillium	c. Bakery products	→ d. Production of antibiotics
4. Yeast	d. Production of antibiotics	→ c. Bakery products

a) Which vaccines are given to infants? Why?

BCG, OPV, DPT/DTwP/DTaP, Hepatitis B, MMR (as per schedule). To build early immunity against serious infections.

b) How is a vaccine produced?

By using weakened/killed pathogens or their antigens/toxoids to safely stimulate immune memory.

c) How do antibiotics cure disease?

They kill or inhibit bacteria (e.g., cell wall/protein synthesis inhibition), thus controlling infection.

d) Are antibiotics for humans and animals the same? Why?

Some molecules overlap but doses/formulations differ; veterinary supervision is required to avoid resistance/residue issues.

e) Why must pathogen strains be safely stored for vaccine work?

For reference, quality control, and further R&D; safe containment prevents accidental spread.

a) What are broad-spectrum antibiotics?

Drugs effective against a wide range of bacteria (gram-positive & gram-negative), e.g., tetracyclines.

b) What is fermentation?

Anaerobic breakdown of sugars by microbes producing acids/alcohols and gases (e.g., yeast making ethanol + CO\(_2\)).

c) Define ‘Antibiotic’.

A microbial product/semi-synthetic that kills/inhibits other microbes, especially bacteria.