Rules Of Biology

Hippophae salicifolia , sea buckthorn, is a thorny Himalayan shrub that produces one of the most nutrient-dense fruits known. It is also one of the few medicinal plants where the useful part can be harvested without killing the plant — which makes it an unusually positive conservation story, and a useful contrast in an exam answer. Scientific classification Kingdom Plantae Clade Angiosperms, Eudicots, Rosids Order Rosales Family Elaeagnaceae Genus Hippophae Species Hippophae salicifolia D. Don Common names Sea buckthorn, seabuckthorn How to identify it Habit. A deciduous, much-branched, thorny shrub or small tree , typically 2–6 m tall. Leaves. Narrow and elongated, willow-like — which is what the species name salicifolia means. Upper surface grey-green; the underside is covered in dense silvery or rusty-brown scales. Thorns. Sharp, stiff and plentiful. They are modified branches, not prickles on the surface. Flowers. Small and inconspicuous, appearing before the leaves. Male an...

Rheum australe , Himalayan rhubarb, is a large perennial herb of the high Himalaya and a classic example of a plant whose chemistry does two opposite things depending on dose. Understanding that dual action is the key to almost every exam question about it. Scientific classification Kingdom Plantae Clade Angiosperms, Eudicots Order Caryophyllales Family Polygonaceae Genus Rheum Species Rheum australe D. Don Common names Himalayan rhubarb Do not confuse it with garden rhubarb ( Rheum rhabarbarum or R. rhaponticum ), which is cultivated for its edible leaf stalks. Same genus, different species, different use. How to identify it Habit. A robust perennial herb, 1–2 m tall in flower, grown from a thick woody rootstock. Root. A large, thick, branched rhizome and root — the part harvested. Cut surfaces are typically yellow to orange. Leaves. Very large, borne on long thick stalks from the base. Blades are broadly ovate to heart-shaped with wavy or lobed margins and co...

Podophyllum hexandrum , the Himalayan mayapple, is the most consequential plant in this group: it produces podophyllotoxin , the raw material for two widely used anticancer drugs. It is also one of the most heavily over-collected plants in the Himalaya, and is now critically endangered. Those two facts belong in the same answer. Scientific classification Kingdom Plantae Clade Angiosperms, Eudicots Order Ranunculales Family Berberidaceae Genus Podophyllum Species Podophyllum hexandrum Royle Common names Himalayan mayapple, Indian podophyllum Related species Podophyllum peltatum — American mayapple How to identify it Habit. An erect, succulent, hairless perennial herb, usually 15–45 cm tall, growing from a creeping horizontal rhizome. Rhizome. Thick, knotty, creeping, carrying bud scars and numerous fibrous roots. This is the part harvested , and it is the reason the plant is endangered. Leaves. Usually two per flowering stem, very large relative to the plant, hel...

Asparagus filicinus is commonly known as fern asparagus or wild shatavari. It is the Himalayan relative of the famous Ayurvedic tonic plant Asparagus racemosus , and most exam questions about it are really questions about how the two differ. Scientific classification Kingdom Plantae Clade Angiosperms, Monocots Order Asparagales Family Asparagaceae (subfamily Asparagoideae; formerly Liliaceae) Genus Asparagus Species Asparagus filicinus Buch.-Ham. ex D. Don Common names Fern asparagus, wild shatavari, ban kurilo Family note. Older textbooks place Asparagus in Liliaceae. Modern classification places it in Asparagaceae. Write whichever your syllabus specifies, but know the change. How to identify it Habit. An erect or scrambling perennial herb, often 30–100 cm, arising from a cluster of tuberous roots. Roots. The diagnostic and useful part: a cluster of fleshy, spindle-shaped tuberous roots radiating from a short rootstock. Stems and cladodes. What look like fine...

Swertia cuneata is a Himalayan gentian whose entire medicinal reputation rests on one property: it is extraordinarily bitter. That bitterness is not a side effect — it is the active principle, and understanding why is the key to most exam questions about this genus. Scientific classification Kingdom Plantae Clade Angiosperms, Eudicots, Asterids Order Gentianales Family Gentianaceae Genus Swertia Species Swertia cuneata D. Don Related species Swertia chirata (chiraita) — the better-known congener How to identify it Habit. An erect perennial herb, typically 30–100 cm tall, with a stout rootstock. Stem. Erect, often branched towards the top, smooth and usually hollow. Leaves. Opposite and stalkless, narrowing at the base — which is what the species name cuneata refers to (wedge-shaped). Margins are usually entire. Flowers. Carried in loose branched clusters. Each flower has four or five petals, pale green to yellowish-white, often with darker veins or streaks. Th...

Read this first. This page is a study method, not a reproduction of any syllabus. Curricula get revised, and the only documents that matter for your exam are your official syllabus, your prescribed textbook, and what your teachers tell you. Use this as a framework for organising your revision, then check every heading against those sources. The mistake almost everyone makes Most students prepare for Grade 12 biology by reading the textbook from page one and hoping it sticks. Biology does not work that way. It is a subject where the same handful of processes appear again and again in different costumes . Consider how often these recur: Surface area to volume ratio — why cells are small, why alveoli are folded, why villi exist, why leaves are thin. Selective permeability and gradients — osmosis, diffusion, active transport, gas exchange, nerve impulses, kidney filtration. Feedback control — enzyme inhibition, hormone regulation, temperature control, blood glucose, population ...