Biology Fundamentals
Biology at this level is systems, deficiencies and named discoveries. Vitamin deficiency diseases and the human organ systems together account for a large fraction of the biology questions asked.
Mental model
Walk biology up the ladder of scale every time: cell → tissue → organ → organ system → organism. Then for each human system fix ONE headline organ and ONE headline failure (heart/blood pressure, kidney/dialysis, pancreas/diabetes, liver/jaundice). Deficiency questions are a fixed triplet — vitamin letter → disease → the food that fixes it — so store them as triplets, never as a list of names.
Associations
A short trigger on the left, everything it pulls with it on the right.
One vitamin, one disease.
A for night blindness, B1 for beri-beri, B3 for pellagra, B12 for pernicious anaemia, C for scurvy, D for rickets in children and osteomalacia in adults, K for delayed clotting. Learn as a table, not as prose.
Fat-soluble: A, D, E, K.
Four fat-soluble vitamins, which the body can store; the B group and C are water-soluble and need regular intake. This single split answers a whole class of questions about deficiency and excess.
Things to remember
The night-before list. Short enough to recall cold.
- 1The cell is the basic unit of life; mitochondria are the powerhouse and ribosomes are where proteins are made.
- 2Photosynthesis uses carbon dioxide, water and light in the presence of chlorophyll to make glucose and release oxygen.
- 3Insulin is produced by the pancreas and lowers blood glucose; thyroxine from the thyroid controls metabolic rate and needs iodine.
- 4Blood group O negative is the universal donor and AB positive the universal recipient.
- 5Gregor Mendel's work on pea plants established the laws of inheritance; DNA's double helix structure was described by Watson and Crick.
- 6Humans have 23 pairs of chromosomes; the male is XY and the female XX, so the father's contribution determines the child's sex.
In detail
- Vitamin triplets: A → night blindness → carrot and green leafy vegetables; C → scurvy → citrus fruit and amla; D → rickets → sunlight and milk; B1 → beriberi → whole grains.
- Photosynthesis happens in the chloroplast and takes in carbon dioxide and water using light to make glucose and release oxygen; respiration in the mitochondrion does the reverse.
- The human body has 206 bones in an adult; the heart has four chambers (two atria, two ventricles).
- Blood group O negative is the universal donor and AB positive the universal recipient.
- DNA carries heredity; genes sit on chromosomes and a normal human cell has 23 pairs, that is 46 chromosomes.
Where people slip
- Rickets is vitamin D deficiency in children; scurvy is vitamin C. Options often pair the disease with the neighbouring vitamin.
Check yourself
Nothing here is scored — it will not change your mastery figures.
Deficiency of which vitamin causes scurvy?
From the question bank
Who is known as the 'Father of Genetics'?
From the question bank
Which cell organelle is known as the 'powerhouse of the cell'?
Books to read
- NCERT Class X — Science
- NCERT Class XI — Biology
- NCERT Class XII — Biology
Official sources
Hand-checked official domains only — the notes above carry no links of their own.