Biology in Everyday Life & Applied Biology

• A microbe (micro-organism) is a tiny living thing seen only under a microscope.
• Main groups are bacteria, fungi, yeast and protozoa.
• The key lesson: not all microbes are harmful – most are useful.
• Useful microbes make curd, bread, antibiotics and biogas.
• Harmful microbes cause disease and are called pathogens.
• Microbes are nature's decomposers, recycling dead matter into soil nutrients.

A microbe (micro-organism) is a tiny living thing seen only under a microscope.

Harmful microbes cause disease and are called pathogens.

Microbes are nature's decomposers, recycling dead matter into soil nutrients.

• Fermentation is microbes breaking down sugars without enough oxygen.
• It produces simpler substances like alcohol or acid and releases gas (often CO2).
• The spongy texture of idli, dosa and bread comes from trapped CO2 gas.
• Yeast ferments sugars into ethanol (alcohol) and CO2.
• Yeast reproduces by budding – a small bud grows out and breaks off as a new cell.
• Lactobacillus ferments milk into curd and adds vitamin B12.

Fermentation is microbes breaking down sugars without enough oxygen.

It produces simpler substances like alcohol or acid and releases gas (often CO2).

The spongy texture of idli, dosa and bread comes from trapped CO2 gas.

Yeast ferments sugars into ethanol (alcohol) and CO2.

Yeast reproduces by budding – a small bud grows out and breaks off as a new cell.

Lactobacillus ferments milk into curd and adds vitamin B12.

• Match each food with the microbe that makes it – a favourite exam trap.
• Baker's yeast and brewer's yeast are the same species, Saccharomyces cerevisiae.
• Swiss cheese holes are CO2 bubbles made by Propionibacterium.
• Roquefort cheese gets its flavour from a fungus grown on it.
• Curd — Lactobacillus (bacteria)
• Bread — Saccharomyces cerevisiae (yeast)
• Ethanol / wine / beer — Saccharomyces cerevisiae
• Toddy — Yeast (fermented palm sap)
• Swiss cheese — Propionibacterium
• Roquefort cheese — Fungus (Penicillium)

Baker's yeast and brewer's yeast are the same species, Saccharomyces cerevisiae.

Swiss cheese holes are CO2 bubbles made by Propionibacterium.

Roquefort cheese gets its flavour from a fungus grown on it.

• All alcoholic drinks begin with fermentation of sugars.
• Wine and beer are made WITHOUT distillation.
• Whisky, brandy and rum are made WITH distillation of the fermented liquid.
• Distillation increases the alcohol concentration.
• Wine, Beer — No
• Whisky, Brandy, Rum — Yes

All alcoholic drinks begin with fermentation of sugars.

Wine and beer are made WITHOUT distillation.

Whisky, brandy and rum are made WITH distillation of the fermented liquid.

• An antibiotic is a chemical made by microbes that kills or stops other microbes.
• Fleming named it after the mould Penicillium notatum.
• Chain and Florey developed it into a medicine; the three shared the 1945 Nobel Prize.
• Antibiotics cured once-deadly diseases like plague, diphtheria, whooping cough and leprosy.
• Crucial point: antibiotics work on bacteria and fungi, NOT viruses – so they cannot cure cold or flu.
• Penicillin — Penicillium (fungus)
• Streptomycin — Streptomyces (bacteria)
• Tetracycline — Streptomyces
• Penicillin was the first antibiotic, discovered accidentally by Alexander Fleming in 1928.

An antibiotic is a chemical made by microbes that kills or stops other microbes.

Fleming named it after the mould Penicillium notatum.

Chain and Florey developed it into a medicine; the three shared the 1945 Nobel Prize.

Crucial point: antibiotics work on bacteria and fungi, NOT viruses – so they cannot cure cold or flu.

Penicillin was the first antibiotic, discovered accidentally by Alexander Fleming in 1928.

• Many drugs come straight from plants – exams test which plant part gives the drug.
• Quinine, the anti-malaria drug, comes from the stem bark of Cinchona tree.
• Quinine works by attacking the malaria parasite inside red blood cells.
• Tulsi has medicinal value due to eugenol (an essential oil).
• Turmeric powder comes from the rhizome (underground stem); its compound is curcumin.
• Pungency (hotness) of chillies is due to capsaicin.
• Quinine — Cinchona — Stem bark
• Opium — Poppy — Latex of fruit
• Hing (Asafoetida) — Ferula — Root
• Rubber — Hevea — Latex (bark)
• Turmeric — Curcuma — Rhizome (stem)
• Ginger — Zingiber — Rhizome (stem)

Many drugs come straight from plants – exams test which plant part gives the drug.

Quinine, the anti-malaria drug, comes from the stem bark of Cinchona tree.

Tulsi has medicinal value due to eugenol (an essential oil).

Turmeric powder comes from the rhizome (underground stem); its compound is curcumin.

Pungency (hotness) of chillies is due to capsaicin.

• A vaccine is weakened or killed germs (or their proteins) put into the body to train immunity.
• It works like a practice fight – the body learns the germ and builds memory.
• Vaccination makes memory B-cells and T-cells plus protective antibodies.
• Smallpox has been completely eradicated by vaccination.
• Polio, diphtheria, pneumonia and tetanus are largely controlled.
• For fast poisons (tetanus, snakebite) ready-made antibodies called antitoxin are injected directly.
• The Hepatitis B vaccine is a recombinant DNA vaccine made in yeast.

A vaccine is weakened or killed germs (or their proteins) put into the body to train immunity.

It works like a practice fight – the body learns the germ and builds memory.

Vaccination makes memory B-cells and T-cells plus protective antibodies.

Smallpox has been completely eradicated by vaccination.

Polio, diphtheria, pneumonia and tetanus are largely controlled.

For fast poisons (tetanus, snakebite) ready-made antibodies called antitoxin are injected directly.

The Hepatitis B vaccine is a recombinant DNA vaccine made in yeast.

• Biotechnology uses living organisms or their enzymes to make useful products.
• Broadly, even making curd, bread and wine is biotechnology.
• Modern usage means using genetically modified (GM) organisms by changing their genes.
• Examples: test-tube baby (IVF), DNA vaccines, and gene therapy.
• Gene therapy means correcting a defective gene.
• GM crops give higher yield, resist pests, tolerate drought/salt and improve nutrition.
• Pest-resistant crops need less spraying, so they reduce chemical pesticide use.

Biotechnology uses living organisms or their enzymes to make useful products.

Broadly, even making curd, bread and wine is biotechnology.

Modern usage means using genetically modified (GM) organisms by changing their genes.

Examples: test-tube baby (IVF), DNA vaccines, and gene therapy.

Gene therapy means correcting a defective gene.

GM crops give higher yield, resist pests, tolerate drought/salt and improve nutrition.

Pest-resistant crops need less spraying, so they reduce chemical pesticide use.

• Microbes are nature's cleaners and recyclers of waste.
• In sewage treatment, bacteria break down organic matter in dirty water.
• Biogas is produced when bacteria decompose waste without oxygen (anaerobic).
• The main gas in biogas is methane (CH4); the methane producers are methanogens.
• Gobar gas uses cow dung as the raw material for biogas.
• Biofertilisers (like Rhizobium, blue-green algae) naturally enrich soil with nitrogen.
• Biocontrol uses living organisms instead of chemicals to control pests.

Microbes are nature's cleaners and recyclers of waste.

In sewage treatment, bacteria break down organic matter in dirty water.

Biogas is produced when bacteria decompose waste without oxygen (anaerobic).

The main gas in biogas is methane (CH4); the methane producers are methanogens.

Gobar gas uses cow dung as the raw material for biogas.

Biofertilisers (like Rhizobium, blue-green algae) naturally enrich soil with nitrogen.

Biocontrol uses living organisms instead of chemicals to control pests.

• Biodegradable waste is matter that microbes can break down naturally.
• Microbes convert biodegradable waste into useful compost / manure.
• Vermiculture is rearing earthworms to convert organic waste into compost.
• The product of vermiculture is vermicompost, a rich natural fertiliser.
• Non-biodegradable wastes like plastic do not decay and cause pollution.

Biodegradable waste is matter that microbes can break down naturally.

Microbes convert biodegradable waste into useful compost / manure.

Vermiculture is rearing earthworms to convert organic waste into compost.

The product of vermiculture is vermicompost, a rich natural fertiliser.

Non-biodegradable wastes like plastic do not decay and cause pollution.

• Seaweeds (marine algae) are an important source of iodine and agar.
• Seaweeds also yield algin and carrageenan, used as food thickeners.
• Light emitted by some marine animals and insects in darkness is bioluminescence.
• Bioluminescence is produced by the enzyme luciferase acting on luciferin.
• The painkiller diclofenac given to cattle nearly wiped out India's vultures.

Seaweeds (marine algae) are an important source of iodine and agar.

Seaweeds also yield algin and carrageenan, used as food thickeners.

Light emitted by some marine animals and insects in darkness is bioluminescence.

Bioluminescence is produced by the enzyme luciferase acting on luciferin.

The painkiller diclofenac given to cattle nearly wiped out India's vultures.

• Blood groups A, B, AB and O are favourite exam topics.
• O group is the universal donor; AB group is the universal recipient.
• Hormones are chemical messengers controlling body functions (e.g. insulin, adrenaline).
• A true fruit develops only from the ovary; a false fruit includes other parts (e.g. apple).
• Stems grow above ground; some, like potato and ginger, are underground stems.
• Distinguishing true vs false fruit and stem vs root is a common BPSC question.
• Develops from — Ovary only — Ovary + other parts
• Example — Mango — Apple, Pear

Blood groups A, B, AB and O are favourite exam topics.

O group is the universal donor; AB group is the universal recipient.

Hormones are chemical messengers controlling body functions (e.g. insulin, adrenaline).

A true fruit develops only from the ovary; a false fruit includes other parts (e.g. apple).

Stems grow above ground; some, like potato and ginger, are underground stems.

Distinguishing true vs false fruit and stem vs root is a common BPSC question.