BiologyPlant Growth & Development· Class 11
Ethylene: ripening hormone
“One ripe banana ripens the whole bunch by releasing ethylene.”
Ethylene gas hastens fruit ripening.
Memory trick: Ethylene ripens fruit.
Fundamentals
1,200 must-knows for NEET & JEE
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
BiologySexual Reproduction in Flowering Plants· Class 12
Double fertilisation
“Flowering plants fertilise twice — once for the baby, once for its lunchbox.”
In angiosperms one sperm fertilises the egg, another forms the nutritive endosperm.
Memory trick: Two fusions: embryo + endosperm.
BiologySexual Reproduction in Flowering Plants· Class 12
Pollination
“Bees pollinating flowers underpin a third of the food we eat.”
Transfer of pollen from anther to stigma, by wind, water or animals.
Memory trick: Anther → stigma.
BiologyLocomotion & Movement· Class 11
Types of muscle
“Your biceps obey you; your heart and gut muscles never ask permission.”
Skeletal (voluntary, striated), cardiac (involuntary, striated) and smooth (involuntary).
Memory trick: Skeletal voluntary; heart & gut not.
BiologyLocomotion & Movement· Class 11
Muscle contraction
“Every movement is billions of molecular ratchets pulling together.”
Muscles shorten as actin and myosin filaments slide past each other.
Memory trick: Sliding-filament mechanism.
BiologyStructural Organisation in Animals· Class 11
Epithelial tissue
“Your skin's outer layer and gut lining are epithelial front-liners.”
A covering/lining tissue that protects, absorbs and secretes.
Memory trick: Covers and lines surfaces.
BiologyStructural Organisation in Animals· Class 11
Connective tissue
“Even blood counts as connective tissue, linking the whole body.”
Binds and supports body parts — blood, bone and cartilage are examples.
Memory trick: Binds & supports (incl. blood).
BiologyBody Fluids & Circulation· Class 11
Blood clotting
“A scab is a finished clot — your body's own emergency patch.”
Platelets and clotting factors seal wounds by forming a fibrin mesh.
Memory trick: Platelets + fibrin plug the leak.
BiologyBody Fluids & Circulation· Class 11
Blood groups
“O-negative is the universal donor, a lifesaver in emergencies.”
The ABO system (A, B, AB, O) plus Rh factor determine safe transfusions.
Memory trick: Match groups before transfusion.
BiologyPrinciples of Inheritance & Variation· Class 12
Linkage
“Linked genes travel as a package unless crossing over splits them.”
Genes on the same chromosome tend to be inherited together.
Memory trick: Same chromosome → inherited together.
BiologyMolecular Basis of Inheritance· Class 12
Mutation
“A single letter change can cause sickle-cell anaemia — or a helpful new trait.”
A change in DNA sequence; the raw material of evolution and a cause of disease.
Memory trick: DNA change = variation source.
BiologyPrinciples of Inheritance & Variation· Class 12
Chromosomal disorders
“One extra chromosome 21 changes development profoundly.”
Extra or missing chromosomes cause conditions like Down (trisomy 21), Turner and Klinefelter syndromes.
Memory trick: Wrong chromosome number.
BiologyPrinciples of Inheritance & Variation· Class 12
Sex-linked inheritance
“Males, with one X, can't mask a faulty X gene.”
Genes on the X chromosome (haemophilia, colour blindness) affect males more often.
Memory trick: X-linked → hits males more.
BiologyEvolution· Class 12
Hardy–Weinberg principle
“Any deviation from it is a fingerprint of evolution happening.”
Allele frequencies stay constant in a large, undisturbed population.
Memory trick: No change = no evolution.
BiologyEvolution· Class 12
Evidence for evolution
“Whales carry tiny leftover hip bones from land-walking ancestors.”
Fossils, homologous organs, embryology and molecular data all support common descent.
Memory trick: Many independent lines agree.
BiologyEvolution· Class 12
Human evolution
“We're the last surviving twig of a once-bushy human family tree.”
Humans evolved over millions of years from ape-like ancestors, with fossils like Australopithecus and Homo erectus.
Memory trick: A long branching lineage.
BiologyEcosystem & Ecology· Class 12
Ecological pyramid
“Grass is plentiful, lions are few — energy thins as it climbs.”
A diagram of numbers, biomass or energy across trophic levels; the energy pyramid is always upright.
Memory trick: Energy pyramid never inverts.
BiologyEcosystem & Ecology· Class 12
Ecological succession
“A bare rock slowly becomes a forest over centuries.”
The gradual, orderly change of a community over time toward a stable climax.
Memory trick: Bare land → climax community.
BiologyEcosystem & Ecology· Class 12
Carbon cycle
“Burning fossil fuels floods the carbon cycle with extra CO₂.”
Carbon flows between air, living things, oceans and fossil fuels.
Memory trick: Photosynthesis and respiration balance it.
BiologyEcosystem & Ecology· Class 12
Nitrogen cycle
“Lightning and bacteria both help turn air nitrogen into life.”
Nitrogen is fixed, nitrified, assimilated and denitrified through the ecosystem.
Memory trick: Fix → use → return.
BiologyOrganisms & Populations· Class 12
Population growth curves
“Every population eventually meets the limits of its environment.”
Growth is J-shaped (unchecked) or S-shaped (limited by carrying capacity).
Memory trick: S-curve = carrying capacity.
BiologyEcosystem & Ecology· Class 12
Keystone species
“Remove sea otters and urchins devour the kelp forests.”
A species whose removal drastically changes an ecosystem.
Memory trick: Small role, huge impact.
BiologyMicrobes in Human Welfare· Class 12
Microbes in human welfare
“Yeast bubbles bread, bacteria set curd — microbes cook with us.”
Microbes make curd, bread, antibiotics, and treat sewage.
Memory trick: Tiny helpers in daily life.
BiologyMicrobes in Human Welfare· Class 12
Fermentation by yeast
“The same reaction leavens bread and brews drinks.”
Yeast converts sugar to alcohol and CO₂ in the absence of oxygen.
Memory trick: Sugar → alcohol + CO₂.