Botany
वनस्पतिशास्त्र · CEE · MECEE-BL Medical Entrance
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chapters done
- Basic Components of Life
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The syllabus asks for
- Structure, types and biological role of carbohydrates and lipids
- Minerals and their biological roles
- Structure, types and biological role of proteins and enzymes
Key points
- Carbohydrates are polyhydroxy aldehydes or ketones; glucose is an aldohexose, fructose a ketohexose, ribulose a ketopentose.
- Sucrose (glucose + fructose, α-1 → β-2) is non-reducing; maltose, lactose and cellobiose are reducing.
- Starch (amylose + amylopectin) and glycogen are α-glucose stores with α-1,4 chains and α-1,6 branches; cellulose is β-1,4 glucose; chitin is β-1,4 N-acetylglucosamine; inulin is a fructose polymer.
- A triglyceride is glycerol esterified with three fatty acids (three water molecules lost); lipids give about 39 kJ g⁻¹, more than twice carbohydrate.
- Phospholipids are amphipathic and form membrane bilayers; steroids have four fused rings; waxes are esters of long-chain alcohols.
- Biodiversity
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The syllabus asks for
- Two-kingdom system, taxonomic hierarchy and binomial nomenclature; five-kingdom and three-domain systems
- Bacteria: cell structure, types, nutrition and growth; general characteristics of cyanobacteria
- Viruses: characteristics, structure, chemical composition and types
Key points
- Linnaeus (1758) gave two kingdoms; Whittaker (1969) gave five — Monera, Protista, Fungi, Plantae, Animalia — chiefly on cell structure, body organisation and mode of nutrition; Woese (1990) placed three domains — Archaea, Bacteria, Eukarya — above them, on rRNA sequences.
- The hierarchy runs kingdom, division, class, order (-ales), family (-aceae), genus, species; species is the basic unit.
- Binomial names (Linnaeus, 1753): Latin, genus capitalised, epithet small, italicised or underlined separately; tautonyms are not allowed in plants.
- Bacteria have a peptidoglycan wall, 70S ribosomes, a nucleoid and often plasmids; they are cocci, bacilli, vibrios or spirilla.
- Gram-positive walls have thick peptidoglycan and stay violet; Gram-negative walls are thin with an outer lipopolysaccharide membrane and stain pink.
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The syllabus asks for
- Phycomycetes, Ascomycetes, Basidiomycetes and Deuteromycetes; structure and reproduction of yeast and Mucor
- Lichens: introduction and types
- Algae: Chlorophyceae, Rhodophyceae and Phaeophyceae; structure and reproduction of Spirogyra
Key points
- Fungi are eukaryotic, achlorophyllous absorptive heterotrophs with chitin walls and glycogen and oil as food; their sexual cycle is plasmogamy, karyogamy, meiosis.
- Phycomycetes have coenocytic hyphae and zygospores or oospores; Ascomycetes form 8 endogenous ascospores in an ascus; Basidiomycetes form 4 exogenous basidiospores on a basidium; Deuteromycetes have no known sexual stage.
- Phytophthora (late blight), Albugo (white rust), Claviceps (ergot), Puccinia (rust), Ustilago (smut), Alternaria (early blight) and Colletotrichum (red rot) are the classic disease fungi.
- Yeast is a unicellular ascomycete that buds, ferments sugar with zymase to ethanol and CO₂, and forms 4 ascospores; its cycle is haplo-diplontic.
- Mucor has a coenocytic mycelium without rhizoids, sporangia with a columella, heterothallic conjugation and a zygospore that is its only diploid stage.
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The syllabus asks for
- Liverworts, hornworts and mosses; structure and reproduction of Marchantia
- Pteridophytes; structure and reproduction of Dryopteris
- Gymnosperms; structure and reproduction of Pinus
Key points
- Bryophytes are non-vascular embryophytes with a dominant haploid gametophyte and a dependent diploid sporophyte; water is needed for their biflagellate sperm.
- Liverworts (thalloid, unicellular rhizoids, scales, elaters), hornworts (horn-like capsule, one chloroplast per cell) and mosses (leafy, multicellular rhizoids, protonema, peristome) are the three classes.
- Marchantia is a dioecious, dichotomous thallus with barrel-shaped air pores and gemma cups; it bears stalked antheridiophores and archegoniophores; its capsule holds haploid spores and diploid elaters.
- Pteridophytes are the first vascular plants; their dominant sporophyte has roots, stems and leaves; most are homosporous, but Selaginella, Marsilea, Salvinia and Azolla are heterosporous.
- Dryopteris has a rhizome with ramenta, circinate fronds, and sori with a reniform indusium; its sporangium opens by the annulus; the spore grows into a free-living, heart-shaped, protandrous prothallus; sperm are multiflagellate.
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The syllabus asks for
- Morphology of root, stem, leaf, inflorescence, flower and fruit
- Diagnostic characters, floral formulae and floral diagrams of Brassicaceae, Solanaceae, Fabaceae and Liliaceae
- Economic importance of viruses, bacteria, blue-green algae, fungi, algae, bryophytes, pteridophytes, gymnosperms and angiosperms of Nepal
- Medicinal plants of Nepal: neem, sarpagandha, yarsagumba, tulasi and ginger
Key points
- A modified organ is identified by its origin, not its looks: nodes, buds or scale leaves mean stem (potato, ginger, onion, Colocasia, Opuntia pad, Asparagus cladode, Citrus thorn); sweet potato, carrot and radish are roots; pea tendrils and Opuntia spines are leaves.
- Racemose inflorescences grow on and open acropetally; cymose ones end in a flower and open basipetally; tulasi has a verticillaster, Euphorbia a cyathium, the fig a hypanthodium and the sunflower a capitulum.
- Flower terms the paper uses: actinomorphic or zygomorphic; hypo-, peri- or epigynous; valvate, twisted, imbricate or vexillary aestivation; monadelphous, diadelphous, syngenesious, epipetalous, tetradynamous and didynamous stamens.
- Placentation is marginal (pea), axile (tomato, lily), parietal (mustard), free central (Dianthus) or basal (sunflower).
- Fruits are simple, aggregate (many free carpels of one flower) or composite (a whole inflorescence); false fruits such as the apple include the thalamus.
- Ecology and Vegetation
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The syllabus asks for
- Pond and forest ecosystems: structure and function; biotic interactions
- Carbon and nitrogen cycles; greenhouse effect, acid rain, ozone-layer depletion and climate change
- Forest types of Nepal; biological invasion
- Ecological succession: hydrosere and xerosere; ecological adaptation
Key points
- An ecosystem has a structure (abiotic factors plus producers, consumers and decomposers) and a function (productivity, decomposition, energy flow, nutrient cycling).
- A pond is zoned into littoral, limnetic, profundal and benthic; a forest is layered from canopy to litter.
- Energy flow is unidirectional and follows Lindeman's 10 % law, so food chains are short; the energy pyramid is always upright while number and biomass pyramids can invert.
- Decomposers work at every trophic level and form a detrital pathway, not the apex of the pyramid.
- The six interactions: mutualism (+ +), commensalism (+ 0), parasitism (+ −), predation (+ −), competition (− −), amensalism (0 −).
- Cell Biology
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The syllabus asks for
- Prokaryotic and eukaryotic cells; the cell theory
- Cell wall, cell membrane, mitochondria, chloroplasts, endoplasmic reticulum, Golgi body, lysosomes, ribosomes, nucleus, chromosomes, cilia, flagella and cell inclusions
- The cell cycle; amitosis, mitosis and meiosis and their significance
Key points
- The cell theory (Schleiden 1838, Schwann 1839, Virchow 1855) has exceptions: viruses are acellular and coenocytic hyphae are multinucleate without cross walls.
- Prokaryotes have no nucleus or membrane-bound organelles, 70S ribosomes, a peptidoglycan wall and binary fission; eukaryotes have a nucleus, 80S cytoplasmic ribosomes and mitosis.
- The plant wall is middle lamella (calcium pectate), primary wall (cellulose) and secondary wall (cellulose plus lignin); plasmodesmata connect neighbouring cells.
- The plasma membrane is a fluid mosaic of phospholipid bilayer and proteins (Singer and Nicolson, 1972), selectively permeable.
- Mitochondria (cristae) and chloroplasts (grana, thylakoids, stroma) are double-membraned and semi-autonomous, with their own DNA and 70S ribosomes; chlorophyll sits in the thylakoid membrane.
- Genetics
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The syllabus asks for
- Composition, structure and functions of DNA and RNA
- DNA replication; the central dogma; the genetic code
Key points
- Griffith showed that a heat-killed virulent pneumococcus could transform a live avirulent one; Avery's group proved with DNase that the principle is DNA; Hershey and Chase proved with ³²P and ³⁵S that DNA, not protein, enters the bacterium.
- A nucleotide is phosphate + pentose + base; purines (A, G) have two rings and pyrimidines (C, T, U) one; nucleotides are joined by phosphodiester bonds into a 5′ → 3′ chain.
- The Watson–Crick helix is right-handed and antiparallel, 2 nm wide, 3.4 nm per turn, 10 bp per turn and 0.34 nm per base pair, with A=T (2 hydrogen bonds) and G≡C (3 hydrogen bonds) — so GC-rich DNA is more stable.
- Chargaff: A = T, G = C, so purines = pyrimidines; one given percentage fixes the other three.
- mRNA carries codons, tRNA is the cloverleaf adaptor with an anticodon and a CCA-3′ amino-acid end, and rRNA is the most abundant RNA and the catalyst that forms peptide bonds.
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The syllabus asks for
- Mendelian terminology and laws; incomplete dominance and co-dominance
- Linkage (complete and incomplete) and crossing over
- Sex-linked inheritance: colour blindness in humans, eye colour in Drosophila
- Gene and chromosomal mutations; polyploidy
- Down's, Turner's, Edwards' and Klinefelter's syndromes; albinism; haemophilia
Key points
- Mendel's pea crosses gave genetics its language (allele, dominant, genotype) and its first two laws: dominance, and segregation — alleles part into gametes unaltered, which meiosis I explains physically.
- The signature ratios flow from gamete combinations: 3 : 1 and 9 : 3 : 3 : 1 in F₂, and test-cross ratios that print out the gametes of the heterozygote directly.
- Incomplete dominance (pink Mirabilis, 1 : 2 : 1) and co-dominance (AB blood group) modify expression, never segregation — pure types reappear in F₂.
- Genes on one chromosome are linked; their recombination frequency (test-cross minority classes) measures distance in centimorgans, capped at 50%.
- Sex-linked recessives (colour blindness, haemophilia, white eye in Drosophila) hit hemizygous males, travel criss-cross through carrier females, and betray themselves by unequal reciprocal crosses.
- Plant Anatomy
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The syllabus asks for
- Plant tissues: characters, classification, structure and functions
- Types of vascular bundles
- T.S. of monocot and dicot root, stem and leaf
Key points
- Tissues are meristematic (still dividing: apical, intercalary and lateral; primary and, by dedifferentiation, secondary) or permanent (simple and complex).
- Parenchyma packs and stores (aerenchyma in hydrophytes), living pectin-rich collenchyma supports growing organs flexibly, and dead lignified sclerenchyma (fibres and stone cells) supports finished ones rigidly.
- Xylem moves water up through dead tracheids and vessels, its parenchyma alone alive; phloem moves food through enucleate sieve tubes serviced by companion cells, with bast fibres for strength.
- Bundle names encode geometry: radial in roots; collateral and bicollateral conjoint bundles in stems; concentric amphivasal (xylem out) and amphicribral (phloem out); open bundles carry cambium, closed do not.
- Roots show epiblema with hairs, a Casparian-striped endodermis with passage cells, pericycle that births lateral roots, and exarch radial groups — few and pith-less in dicots, polyarch with a big pith in monocots.
- Plant Physiology
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The syllabus asks for
- Diffusion, diffusion pressure deficit, osmosis and plasmolysis
- Osmotic pressure and potential, water potential, wall pressure and turgor pressure
- Absorption, imbibition, ascent of sap, transpiration, guttation and wilting
Key points
- Diffusion needs no membrane; osmosis is water diffusing across a selectively permeable one; plasmolysis (reversible) demonstrates both the membrane's selectivity and the cell sap's osmotic strength.
- Water potential Ψw = Ψs + Ψp rules every movement: pure water is zero, all else negative, and water runs from less negative to more negative; van't Hoff's Ψs = −imRT sizes any solution.
- The older DPD = OP − TP is the same physics with flipped signs (Ψw = −DPD): fully turgid means DPD zero; flaccid means DPD = OP.
- Roots absorb through root hairs by apoplast, symplast and aquaporin routes, with the Casparian strip as the membrane checkpoint; imbibition by colloids (protein strongest) starts germination.
- Root pressure (≈0.1–0.2 MPa) is too feeble and too nocturnal to lift sap; the sun does it instead — transpiration tension dragging a cohesive, adhesive water column from soil to air (Dixon and Joly), with xylem under negative pressure.
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The syllabus asks for
- Photosynthetic pigments; photosystems I and II; the light reactions
- Calvin cycle (C3), Hatch–Slack pathway (C4) and photorespiration; factors; bacterial photosynthesis
- Aerobic and anaerobic respiration: glycolysis, oxidative decarboxylation, Krebs cycle, electron transport and oxidative phosphorylation; factors
Key points
- Chlorophyll a (Mg-centred) alone converts light energy; accessory pigments widen the catch and protect the reaction centres P680 (PS II, acting first) and P700 (PS I).
- The Z-scheme drags electrons from water (photolysis at the Mn₄CaO₅ complex, O₂ and protons into the lumen) to NADP⁺, minting ATP chemiosmotically on the way; cyclic flow around PS I adds ATP only, balancing the 3 : 2 budget.
- The stromal Calvin cycle carboxylates RuBP via RuBisCO into 3-PGA and, at 3 ATP + 2 NADPH per CO₂, builds glucose for 18 ATP + 12 NADPH.
- Photorespiration — RuBisCO fixing O₂ — wastes carbon through a three-organelle salvage loop; C4 plants suppress it spatially (Kranz anatomy, PEP carboxylase pump, 5 ATP per CO₂) and CAM plants temporally.
- Blackman's limiting-factor law and the two compensation points govern how light, CO₂ (now 0.043%), temperature and water set the photosynthetic rate; bacteria photosynthesise with H₂S and release no O₂.
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The syllabus asks for
- Auxins, gibberellins and cytokinins: roles and applications
- Seed germination and its types; seed dormancy
Key points
- Auxin (IAA) was hunted down through the Darwin–Boysen-Jensen–Paál–Went experiments; it elongates cells, enforces apical dominance, roots cuttings and, as 2,4-D, selectively kills dicot weeds — always with a bell-shaped, tissue-specific dose response.
- Gibberellins, discovered through the bakanae fungus, elongate internodes (curing genetic dwarfs), bolt rosettes, break dormancy and order the aleurone to make α-amylase.
- Cytokinins (kinetin, then natural zeatin from maize) drive cell division with auxin, free lateral buds, and delay senescence; the auxin : cytokinin ratio steers tissue culture between roots, shoots and callus.
- Germination begins with imbibition, is powered by aerobic respiration, and is fed when embryo gibberellin switches on the aleurone; the radicle leads the way out.
- Hypocotyl growth lifts the cotyledons in epigeal species (bean, castor), epicotyl growth leaves them buried in hypogeal ones (pea, maize), and mangroves skip the wait by vivipary.
- Developmental and Applied Botany
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The syllabus asks for
- Asexual reproduction
- Sporogenesis and gametogenesis in angiosperms
- Pollination and fertilization
- Monocot and dicot embryos; types and functions of endosperm
Key points
- Plants clone themselves by rhizomes, tubers, bulbs, runners, leaf buds and even apomictic seed — fast and faithful, but variation-free; growers exploit the same tricks by cutting, layering and grafting.
- The anther's tapetum feeds microspores produced four-at-a-time by PMC meiosis; each becomes a sporopollenin-armoured pollen grain carrying a tube cell and a generative cell (source of the two gametes).
- The ovule's single functional megaspore builds, by three mitoses, the 7-celled, 8-nucleate Polygonum embryo sac — egg apparatus, central cell with two polar nuclei, three antipodals.
- Pollination spans autogamy to xenogamy on wind, water, insects, birds and bats, with cleistogamy guaranteeing selfing and dicliny, dichogamy, herkogamy, heterostyly and self-incompatibility enforcing crossing.
- Double fertilization — syngamy making the 2n zygote, triple fusion the 3n endosperm — is unique to angiosperms and economical: food tissue is made only when an embryo exists.
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The syllabus asks for
- Plant tissue culture: concept, types and applications
- Genetic engineering: concept and applications
- Biofertilizers, green manures, plant breeding, bio-engineering, food safety and security
Key points
- Tissue culture milks totipotency on MS medium: sterilised explants pass through callus to shoots (cytokinin) and roots (auxin), then hardening — the engine of micropropagation and the finishing step of all plant genetic engineering.
- Specialised cultures earn their keep: meristems for virus-free stock, anthers for haploids and instant pure lines, rescued embryos for wide crosses, fused protoplasts for somatic hybrids, liquid nitrogen for germplasm.
- Genetic engineering cuts with restriction enzymes, glues with ligase, ferries genes on plasmid or Ti vectors, selects on markers, and amplifies DNA with PCR; its products range from Humulin and Flavr Savr to Bt crops and Golden Rice, under Cartagena-style biosafety rules (and no registered GM cultivation in Nepal).
- Plant breeding improves crops by introduction, selection, hybridisation, mutation and polyploidy — trading variation for uniformity carefully, using backcrosses for single resistance genes and heterosis for yield.
- Biofertilizers inoculate the soil with nitrogen fixers, phosphate solubilisers and mycorrhiza; green manures sacrifice a legume crop to feed the next one.
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The paper
3 hours, 200 single-best-answer MCQs with four options, 200 marks, 0.25 deducted per wrong answer, merit list from the 50th percentile
| Section | Questions | Marks each | Total |
|---|---|---|---|
| Zoology | 40 | 1 | 40 |
| Botany | 40 | 1 | 40 |
| Chemistry | 50 | 1 | 50 |
| Physics | 50 | 1 | 50 |
| Mental Agility Test | 20 | 1 | 20 |
Where the questions are
Questions each part carries in the paper, out of 40. Area totals follow the official syllabus; where single chapters are shown, the split between them is the NEBians estimate.
- Biodiversity9 Qs
- Genetics6 Qs
- Plant Physiology6 Qs
- Cell Biology5 Qs
- Developmental and Applied Botany5 Qs
- Ecology and Vegetation4 Qs
- Plant Anatomy3 Qs
- Basic Components of Life2 Qs