Explore the beneficial roles of microbes in household foods, industrial chemicals, sewage treatment, and agriculture. By the end of this module, you will understand:
Estimated Reading Time: 20 minutes | Difficulty Level: Easy | Prerequisites: Cell types.
Harnessing microbes enables cheap industrial synthesis of medicines, eco-friendly municipal water filtration, and the creation of biofertilizers that replace chemical alternatives.
Sewage filtration flow: \[\text{Raw Sewage} \xrightarrow{\text{Primary Settling}} \text{Effluent} \xrightarrow{\text{Aerobic Tanks (Flocs)}} \text{Settling Tank (Sludge)} \xrightarrow{\text{Anaerobic Digester}} \text{Biogas}\]
Microbes are major components of biological systems on Earth.
| Chemical Agent | Source Microbe | NEET High-Yield Medical Use |
|---|---|---|
| Cyclosporin A | *Trichoderma polysporum* (fungus) | Immunosuppressant in organ transplantation |
| Statins | *Monascus purpureus* (yeast) | Lowers blood cholesterol (inhibits synthesis) |
| Streptokinase | *Streptococcus* (bacterium) | Clot buster for myocardial infarction patients |
❌ Misconception: Bacteria are only harmful disease-causing pathogens.
✔ Correction: The vast majority of bacterial species are non-pathogenic, and many are critical for human digestion, yogurt production, and waste treatment.
Clinical Correlation: Cyclosporin A allows successful organ transplants by selectively blocking T-cell activation, preventing graft rejection.
1. (NEET PYQ) Which of the following is correct for the blood-cholesterol lowering agent statin?
Correct Answer: B. Produced by Monascus purpureus, competitive inhibitor
Explanation: Statins are produced by the yeast *Monascus purpureus*. They competitively inhibit the enzyme HMG-CoA reductase responsible for cholesterol synthesis.
A population (not an individual) has unique attributes: density, natality (birth rate), mortality (death rate), sex ratio, and age distribution. Plotting age groups gives an age pyramid — expanding (broad base, growing), stable, or declining (narrow base). Population size changes as: Nt+1 = Nt + (B + I) − (D + E), where B, I, D and E are births, immigration, deaths and emigration.
1. (NEET PYQ) The population growth curve that is bounded by a carrying capacity (K) displays a shape that is:
Correct Answer: A. Sigmoid (logistic)
Explanation: Under limited resources, populations exhibit logistic growth which forms a Sigmoid (S-shaped) curve, bounded by the carrying capacity (K).
Energy flows through the ecosystem in one direction: producers → primary consumers → secondary consumers → decomposers. By the 10% law (Lindeman), only about 10% of energy at one trophic level passes to the next, so food chains rarely exceed 4–5 links. Ecological pyramids represent number, biomass or energy across trophic levels: the pyramid of energy is always upright, while pyramids of number and biomass can be inverted (e.g. an inverted biomass pyramid in a pond, where tiny phytoplankton support larger zooplankton).
Biogeochemical cycles recycle nutrients between organisms and the environment:
Biodiversity patterns: species richness generally rises from the poles toward the equator (latitudinal gradient) — the tropics are most diverse. Biodiversity loss is driven by the "evil quartet": habitat loss (the biggest cause), over-exploitation, invasive alien species, and co-extinctions.
1. (NEET PYQ) What is the Z value (regression coefficient slope) of the species-area relationship on a very large area like an entire continent?
Correct Answer: C. 0.6 to 1.2
Explanation: For small localized areas, the slope Z is in the range of 0.1 to 0.2. However, for extremely large areas like entire continents, the slope Z becomes much steeper, in the range of 0.6 to 1.2.