Biology
🔒 Log in to trackDiseases, pathogens, vectors and vaccines
🔒 Log in to trackEvery common disease belongs to one pathogen type: bacteria, virus, protozoa or fungus. Many are carried by one named vector, such as a mosquito or fly. Add the vaccine and the scientist who found it, and most questions are covered.
Disease and pathogen type
A pathogen is a germ that causes disease. Sort each disease into its group first.
| Type | Diseases |
|---|---|
| Bacteria | TB, cholera, typhoid, tetanus, leprosy, plague, whooping cough, anthrax |
| Virus | Dengue, chikungunya, rabies, polio, measles, mumps, AIDS, COVID-19, smallpox, influenza, jaundice (hepatitis) |
| Protozoa | Malaria, kala-azar, amoebiasis (dysentery), sleeping sickness |
| Fungus | Ringworm, athlete's foot |
Tip: The bacterial six are cholera, typhoid, TB, tetanus, leprosy and plague. The viral five are dengue, rabies, polio, measles and AIDS.
Vectors: who carries what
A vector is a living carrier of a pathogen.
| Vector | Disease |
|---|---|
| Female Anopheles | Malaria (Plasmodium) |
| Aedes aegypti | Dengue, chikungunya, zika |
| Culex | Filariasis or elephantiasis (Wuchereria bancrofti) |
| Sandfly | Kala-azar (Leishmania) |
| Tsetse fly | Sleeping sickness (Trypanosoma) |
| Rat flea | Plague |
Only the female mosquito bites.
Watch: AIDS is never spread by mosquitoes. It spreads only by blood, unsafe sex and shared needles.
Vaccines, antibiotics and discoverers
| Scientist | Contribution |
|---|---|
| Edward Jenner | First vaccine: smallpox, 1796. 'Vaccine' comes from 'vacca', cow |
| Louis Pasteur | Germ theory, pasteurisation, rabies vaccine |
| Robert Koch | TB bacterium (Mycobacterium tuberculosis), also anthrax and cholera |
| Alexander Fleming | Penicillin, 1928, the first antibiotic (mould Penicillium notatum) |
| Florey and Chain | Made penicillin into a medicine |
| Banting and Best (1921) | Insulin for diabetes |
| Ronald Ross | Proved mosquitoes carry malaria (worked in India, Nobel 1902) |
| Joseph Lister | Antiseptic surgery (carbolic acid) |
Key numbers and controls
- Smallpox was the first disease eradicated. WHO declared it in 1980.
- BCG vaccine protects against TB. MMR covers measles, mumps and rubella.
- Polio drops belong to the Pulse Polio campaign.
- Cholera, typhoid and jaundice spread through contaminated water and food.
- Safe drinking water and vaccination are the cheapest shields.
Scale words
| Word | Meaning |
|---|---|
| Endemic | Always present in a local area |
| Epidemic | Outbreak in a region |
| Pandemic | Worldwide outbreak (COVID-19) |
Blood values and disorders
- Normal haemoglobin is about 12 to 16 g/dL. Low haemoglobin is anaemia.
- Normal RBC count is about 5 million per mm³. WBC is about 6,000 to 8,000 per mm³.
- An RBC lives about 120 days.
- Thalassaemia and sickle-cell anaemia are genetic blood disorders. They do not spread from person to person.
Note: Antibiotics act only on bacteria. They do not cure viral infections.
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Disease and pathogen type
'TB is caused by a', 'which is a viral / protozoan disease', 'ringworm is caused by'.
Name the disease.
Find its group: bacteria, virus, protozoa or fungus.
Check the options against that group.
Classify the disease first, then eliminate options.
Ringworm is caused by which type of pathogen?
Show solutionHide solution
It is not a worm.
It is a skin infection of a fungus.
Fungus
Vector and disease
'Dengue is spread by which mosquito', 'malaria is transmitted by', 'which fly causes sleeping sickness'.
Recall the vector table.
Anopheles gives malaria, Aedes gives dengue, Culex gives filariasis.
Remember only the female mosquito bites.
Each vector carries one family of disease.
Elephantiasis (filariasis) is transmitted by which vector?
Show solutionHide solution
The worm is Wuchereria bancrofti.
Its carrier is the Culex mosquito.
Culex mosquito
Vaccines and eradication
'BCG protects against', 'first vaccine', 'which disease was eradicated', 'MMR'.
BCG is for TB. MMR is for measles, mumps and rubella.
Jenner's smallpox vaccine came in 1796.
Smallpox was eradicated in 1980.
The vaccine word root and the eradication year are the most repeated facts.
Which was the first disease eradicated worldwide?
Show solutionHide solution
WHO declared it in 1980.
Jenner's 1796 vaccine fought it.
Smallpox
Scientist and medicine or discovery
'Penicillin was discovered by', 'who discovered the TB bacterium', 'pasteurisation', 'insulin'.
Fleming: penicillin 1928.
Koch: TB bacterium. Pasteur: germ theory, rabies vaccine.
Banting and Best: insulin 1921.
Do not mix Koch, the bacteriologist, with Pasteur.
Penicillin, the first antibiotic, was discovered by whom?
Show solutionHide solution
It came from the mould Penicillium notatum.
The year was 1928.
Alexander Fleming
Epidemic words and lifestyle diseases
'A disease spread worldwide is a', 'diabetes is caused by lack of', 'AIDS is caused by'.
Local and constant is endemic. Regional is epidemic. Worldwide is pandemic.
Diabetes means lack of insulin from the pancreas.
AIDS does not spread by touch or mosquitoes.
Scale words differ only by how far the disease spreads.
COVID-19 spread across the world in 2020. What is such an outbreak called?
Show solutionHide solution
It crossed countries and continents.
That is beyond an epidemic.
Pandemic
Health numbers and blood disorders
'Normal haemoglobin range', 'lifespan of RBC', 'sickle-cell is a', 'thalassaemia'.
Haemoglobin: 12 to 16 g/dL.
RBC life: 120 days.
Sickle-cell and thalassaemia are genetic blood disorders.
Learn the normal values. The disorders hang off them.
The average lifespan of a red blood cell is how long?
Show solutionHide solution
Recall the normal value.
The spleen removes old cells.
120 days
Shortcuts that save time
A disease in this list is bacterial. Polio, measles, AIDS, dengue, rabies, chickenpox and hepatitis are viral. Malaria and kala-azar are protozoan.
Which of these is a viral disease: typhoid, cholera, measles, tetanus?
Show solutionHide solution
Typhoid, cholera and tetanus are bacterial.
Measles is on the viral list.
Measles
Aedes also spreads chikungunya, yellow fever and Zika (day-biting). Only the female mosquito bites for blood.
Mistakes to avoid
Where most students lose marks on this subtopic.
Calling malaria a bacterial or viral disease.
Malaria is protozoan (Plasmodium).
Crediting Pasteur with the smallpox vaccine.
Jenner made it. Pasteur made the rabies vaccine.
Thinking antibiotics cure viral infections.
Antibiotics act only on bacteria.
Thinking ringworm is caused by a worm.
Ringworm is a fungal infection.
Saying mosquitoes spread AIDS.
AIDS spreads only by blood, unsafe sex and shared needles.
Quick revision
Read this the night before the exam.
Bacterial six: TB, cholera, typhoid, tetanus, leprosy, plague. Viral five: dengue, rabies, polio, measles, AIDS.
Protozoa: malaria, kala-azar, amoebiasis, sleeping sickness. Fungus: ringworm, athlete's foot.
Anopheles: malaria. Aedes: dengue. Culex: elephantiasis. Sandfly: kala-azar. Tsetse: sleeping sickness. Rat flea: plague.
Jenner: smallpox vaccine 1796. Pasteur: rabies. Koch: TB. Fleming: penicillin 1928. Banting and Best: insulin.
Smallpox eradicated 1980. BCG for TB. Pandemic means worldwide.
Haemoglobin 12 to 16 g/dL. Thalassaemia and sickle-cell are genetic.
Practice: 20 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 10 questions
Suggested time 3 min · wrong answers go to your mistake notebook automatically.