NDA Biology · Teaching notes
Microbiology and Disease — NDA Biology
Microbiology and Disease is pure named-fact recall — 21 PYQs across 2017–2025, every one EASY or MODERATE, zero derivation. The whole chapter rests on one skill: matching a disease to the exact organism that causes it, and knowing what KIND of organism that is (virus, bacterium, protozoan, fungus or worm). The bank's favourite trap is the swapped pair — Malaria with Mycobacterium, TB with Plasmodium — so the pairings have to be exactly right. The chapter teaches in three movements: (1) Pathogens and Diseases — the master disease↔pathogen↔type table that carries most of the marks, plus how diseases spread (waterborne, viral genetic material, the platelet drop in dengue); (2) Disease Vectors — the malaria transmission cycle and the vector-vs-pathogen distinction (female Anopheles carries, Plasmodium causes); (3) Antibiotics and Useful Microbes — Fleming and penicillin, why antibiotics miss viruses, β-lactamase resistance, and the friendly microbes (Lactobacillus, probiotics). 13 concepts, every PYQ tagged. Most are reference tables: memorise the table, win the marks.
Subtopic notes
Pathogens and Diseases — the Master Pairings
13 PYQsA pathogen is a disease-causing organism; the NDA tests you on which exact organism causes which disease, and what KIND of organism it is — virus, bacterium, protozoan, fungus or worm.
Open note
Disease Vectors — Malaria
1 PYQsA vector is the carrier that moves a pathogen from host to host; for malaria the vector is the female Anopheles mosquito, while the pathogen it carries is the protozoan Plasmodium.
Open note
Antibiotics and Useful Microbes
7 PYQsAn antibiotic is a chemical made by one microbe that kills or stops another; this subtopic covers Fleming's discovery of penicillin, why antibiotics miss viruses, how bacteria resist them, and the friendly microbes we put to work.
Open note
PYQ weightage by concept
10 concepts · 21 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
10 concepts · 21 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| The disease–pathogen–type table | 5 | 24% |
| Disease mechanisms and the odd facts | 4 | 19% |
| How diseases spread — waterborne, airborne, vector | 2 | 10% |
| Viruses — nature and genetic material | 2 | 10% |
| The five kinds of pathogenfoundation | — | — |
| Concept | PYQs | Share |
|---|---|---|
| Antibiotics — discovery and how they work | 3 | 14% |
| Useful microbes — Lactobacillus and probiotics | 2 | 10% |
| Antibiotic resistance — β-lactamase | 1 | 5% |
| Worm diseases — elephantiasis | 1 | 5% |
Formula & revision sheet
0 formulas · 9 reference tables · 17 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 9 reference tables · 17 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (4)
The disease–pathogen–type table9 rows
| Disease | Pathogen | Type |
|---|---|---|
| Malaria | Plasmodium | Protozoan |
| Sleeping sickness | Trypanosoma | ProtozoanQ Transmitted by the tsetse fly. NDA 2017. |
| Tuberculosis (TB) | Mycobacterium | BacteriumQ TB = Mycobacterium, NOT Plasmodium. The bank swaps this with malaria. NDA 2025. |
| Cholera | Vibrio cholerae | Bacterium |
| Typhoid | Salmonella typhi | BacteriumQ AIDS, dengue and COVID-19 are viral; typhoid is the bacterial one. NDA 2019, 2022. |
| Smallpox | Variola virus | VirusQ Eradicated worldwide in 1980 (WHO). NDA 2021. |
| AIDS | HIV | Virus |
| Chickenpox | Varicella zoster | Virus |
| Elephantiasis (filariasis) | Wuchereria bancrofti | Worm |
How diseases spread — waterborne, airborne, vector5 rows
| Route | Diseases | Key fact |
|---|---|---|
| Waterborne | Cholera, typhoid, jaundice | Spread by contaminated food or waterQ Jaundice is the waterborne answer when paired against TB (air), rabies (bite), arthritis (none). NDA 2018. |
| Cholera (route) | Vibrio cholerae | Contaminated food/water → severe watery diarrhoeaQ Not loss of memory, not a muscle disease, not genetic. NDA 2019. |
| Airborne | Tuberculosis, cold, flu, COVID-19 | Spread by respiratory droplets |
| Vector-borne | Malaria, dengue, filariasis | Carried by a mosquito or fly |
| Animal bite | Rabies | Dog or bat bite; not waterborne |
Viruses — nature and genetic material5 rows
| Statement about viruses | True or false |
|---|---|
| Need living cells to reproduce | True |
| All viruses are parasites | True |
| Can synthesize food by photosynthesis | FalseQ Viruses have no chloroplasts or organelles — they cannot photosynthesise. The 'NOT true' answer. NDA 2019. |
| Behave like chemicals outside a host | True |
| HIV genetic material | Single-stranded RNAQ HIV is a retrovirus — single-stranded RNA, not DNA. NDA 2018. |
Disease mechanisms and the odd facts4 rows
| Question | Answer | Note |
|---|---|---|
| Dengue reduces which blood cells? | Platelets (thrombocytes) | Causes bleeding risk; NDA 2017Q |
| Streptococcus mutans makes slime from | Sugar | Sticky glucan grips tooth enamel; NDA 2023Q |
| ECG records the activity of the | Heart | Electrical activity; brain = EEG. NDA 2019Q |
| Agency enforcing food-safety law in India | FSSAI | Not FDA, WHO or FAO. NDA 2017Q |
Watch out for (9)
- Malaria ↔ Plasmodium, TB ↔ Mycobacterium — never swapped→ The disease–pathogen–type table
- Typhoid is the bacterial odd-one-out→ The disease–pathogen–type table
- Sleeping sickness is a protozoan, not a worm→ The disease–pathogen–type table
- Cholera is NOT a memory, muscle or genetic disease→ How diseases spread — waterborne, airborne, vector
- TB is airborne, not waterborne→ How diseases spread — waterborne, airborne, vector
- HIV carries RNA, not DNA→ Viruses — nature and genetic material
- Viruses cannot make their own food→ Viruses — nature and genetic material
- Dengue hits platelets, not white cells→ Disease mechanisms and the odd facts
- ECG = heart, EEG = brain→ Disease mechanisms and the odd facts
Reference tables (1)
The malaria vector — female Anopheles3 rows
| Mosquito | Disease carried | Note |
|---|---|---|
| Female Anopheles | Malaria | Only the FEMALE bites; pathogen = PlasmodiumQ Vector = female Anopheles; pathogen = Plasmodium. Keep the two distinct. NDA 2025. |
| Aedes | Dengue, chikungunya, Zika | Daytime biter; tiger-striped legs |
| Culex | Filariasis, Japanese encephalitis | Carries the elephantiasis worm Wuchereria |
Watch out for (2)
- It's the FEMALE Anopheles, not the male→ The malaria vector — female Anopheles
- Vector ≠ pathogen→ The malaria vector — female Anopheles
Reference tables (4)
Antibiotics — discovery and how they work3 rows
| Fact | Answer |
|---|---|
| Penicillin was discovered by | Alexander Fleming (1928)Q From the Penicillium mould killing Staphylococcus. NDA 2025. |
| Are antibiotics obtained from microbes? | Yes — fungi and bacteriaQ 'No antibiotic from any microbe' is the FALSE statement. NDA 2017. |
| Do antibiotics affect viruses? | No — viruses lack metabolic pathwaysQ Antibiotics target bacterial pathways; viruses have none, so taking antibiotics does NOT cure a viral infection. NDA 2020. |
Antibiotic resistance — β-lactamase4 rows
| Mechanism of resistance | Correct? |
|---|---|
| Degrade penicillin with the enzyme β-lactamase | Yes — the correct mechanismQ β-lactamase breaks the β-lactam ring. NDA 2019. |
| Store the antibiotic in a vacuole | No — a distractor |
| Degrade it with lactic acid dehydrogenase | No — wrong enzyme |
| Penicillin is simply not absorbed | No — a distractor |
Useful microbes — Lactobacillus and probiotics3 rows
| Useful microbe / term | Role |
|---|---|
| Lactobacillus (Lactic Acid Bacillus) | Curdles milk — ferments lactose to lactic acidQ The acidification + curdling agent. NDA 2017. |
| Probiotic | Live microbial food supplement (beneficial bacteria)Q Not an antacid, antibiotic, or organic food. NDA 2017. |
| Saccharomyces cerevisiae (yeast) | Baking and brewing (fermentation) |
Worm diseases — elephantiasis3 rows
| Disease | Causal worm | Type |
|---|---|---|
| Elephantiasis (filariasis) | Wuchereria bancrofti | Filarial roundwormQ Blocks lymph vessels → limb swelling. Vector is the Culex mosquito. NDA 2017. |
| Ascariasis | Ascaris lumbricoides | Intestinal roundworm |
| Fascioliasis | Fasciola hepatica | Liver fluke (flatworm) |
Watch out for (6)
- Antibiotics do nothing to viruses→ Antibiotics — discovery and how they work
- Antibiotics DO come from microbes→ Antibiotics — discovery and how they work
- The resistance enzyme is β-lactamase, not 'lactic acid dehydrogenase'→ Antibiotic resistance — β-lactamase
- A probiotic is live microbes, not an antibiotic→ Useful microbes — Lactobacillus and probiotics
- Milk curdles by Lactobacillus, not yeast→ Useful microbes — Lactobacillus and probiotics
- Wuchereria is the pathogen; Culex is only the vector→ Worm diseases — elephantiasis