Fundamentals
The core facts every aspirant should own — each a titled nugget with a real-world story, the concept in plain words, and a memory trick. Works even when the internet doesn't.
300 fundamentals
“Skin is your castle wall; antibodies are trained archers who remember each enemy.”
Innate immunity is general and present from birth; acquired immunity is specific and develops after exposure.
Memory trick: Acquired immunity remembers.
“A vaccine trains your army; antivenom lends you someone else's.”
Active immunity is your own antibodies (vaccine/infection); passive is ready-made antibodies (mother's milk, antivenom).
Memory trick: Vaccine = active; antivenom = passive.
“Taking antibiotics for a viral cold does nothing but breed resistance.”
Antibiotics kill or stop bacteria; they don't work on viruses.
Memory trick: Useless against viruses.
“Sperm and egg meet in the oviduct; the embryo then travels to implant in the uterus.”
In humans, fertilisation occurs in the fallopian tube, not the uterus.
Memory trick: Egg meets sperm in the oviduct.
“A temporary organ that is baby's lifeline for nine months.”
Connects the embryo to the mother for nutrient, gas and waste exchange, and makes hormones.
Memory trick: Baby's lifeline in the womb.
“We reprogrammed bacteria to brew human insulin — a medical revolution.”
Inserting a desired gene into a vector and host cell to mass-produce a product.
Memory trick: Gene + vector + host.
“Biology's precise scissors, cutting DNA only at chosen 'words'.”
Molecular scissors that cut DNA at specific palindromic sequences.
Memory trick: Cut at specific sites.
“PCR is a DNA photocopier — and the backbone of modern diagnostics.”
A technique that makes millions of copies of a DNA segment using primers and Taq polymerase.
Memory trick: Amplifies DNA copies.
“That 10% rule is why top predators are always rare.”
Energy flows one way through trophic levels, with only ~10% passing to the next.
Memory trick: ~10% up each level.
“Nature's clean-up crew, returning nutrients to the soil.”
Bacteria and fungi that break down dead matter and recycle nutrients.
Memory trick: Recyclers of the ecosystem.
“A diverse ecosystem is a diversified portfolio — more resilient to shocks.”
The variety of life; higher diversity makes ecosystems more stable.
Memory trick: More variety = more stability.
“One tidy system to sort every living thing from bacteria to blue whales.”
Whittaker grouped life into Monera, Protista, Fungi, Plantae and Animalia.
Memory trick: Monera, Protista, Fungi, Plantae, Animalia.
“A virus is a hijacker — lifeless until it commandeers a living cell.”
Non-cellular particles of nucleic acid in a protein coat; they replicate only inside a host.
Memory trick: Alive only inside a host.
“The bacteria in your gut outnumber your own cells.”
Single-celled prokaryotes; some help (gut flora, nitrogen fixers), some cause disease.
Memory trick: Prokaryotic, everywhere.
“Linnaeus gave every organism a universal two-word ID card.”
Every species gets a two-part Latin name: genus + species (e.g. Homo sapiens).
Memory trick: Genus capitalised, species lowercase.
“An apple's flesh is the angiosperm's clever way of protecting its seeds.”
Gymnosperms bear naked seeds (pines); angiosperms bear seeds enclosed in fruit (flowering plants).
Memory trick: Angiosperm = flowering, fruit-covered seed.
“A plant's two-lane plumbing: water up, food out.”
Xylem carries water and minerals up; phloem carries food (sugars) both ways.
Memory trick: Xylem = water up; phloem = food.
“The plant's growth 'engines' sit at root and shoot tips.”
Regions of actively dividing cells responsible for plant growth.
Memory trick: Dividing cells → growth zones.
“Autumn reveals the carotenoids once green chlorophyll fades.”
Chlorophyll a and b plus carotenoids capture light for photosynthesis.
Memory trick: More than one pigment harvests light.
“Plants 'breathe' and sweat through microscopic mouths on their leaves.”
Tiny leaf pores that let gases in and out and control water loss.
Memory trick: Gas exchange + water control.
“Legumes host bacteria that fertilise the soil for free.”
Certain bacteria convert inert atmospheric N₂ into usable ammonia for plants.
Memory trick: Bacteria turn N₂ into plant food.
“A plant leaning toward a window is auxin at work.”
Auxin promotes cell elongation and drives bending toward light (phototropism).
Memory trick: Auxin → growth toward light.
“They can make a cabbage shoot up metres tall.”
Gibberellins promote stem elongation and seed germination.
Memory trick: Gibberellin → stem growth.
“In a drought, ABA tells the plant to shut its pores and wait.”
ABA is the stress hormone — it closes stomata and induces dormancy.
Memory trick: ABA = stress/dormancy.