Biology
जीवविज्ञान · Class 11 · Code 2011 (CDC Bio.201)
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chapters done
- Botany
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The syllabus asks for
- Biomolecules [4]: carbohydrates, proteins, lipids, nucleic acids, minerals, enzymes, water
- Cell [8]: prokaryotic and eukaryotic cell; cell wall; cell membrane; mitochondria; plastids; endoplasmic reticulum; golgi apparatus; lysosomes; ribosomes; nucleus; chromosomes; cilia and flagella; cell inclusions
- Cell division [3]: cell cycle; amitosis; mitosis; meiosis
Key points
- Condensation joins monomers into polymers with the loss of water; hydrolysis reverses it. Carbohydrates → glycosidic bonds, proteins → peptide bonds, lipids → ester bonds, nucleic acids → phosphodiester bonds.
- Lipids yield about 39 kJ g⁻¹ against 17 kJ g⁻¹ for carbohydrate and protein.
- DNA is an antiparallel right-handed double helix: A=T (2 H-bonds), G≡C (3 H-bonds), 0.34 nm per base pair, 3.4 nm and 10 base pairs per turn, diameter 2 nm. Chargaff: A = T and G = C.
- Enzymes are protein catalysts that lower activation energy; they are specific and have an optimum temperature and pH. Induced fit, not lock and key, is the accepted model.
- Prokaryotes lack a nuclear envelope and membrane-bound organelles and have 70S ribosomes; eukaryotes have both and 80S cytoplasmic ribosomes.
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The syllabus asks for
- Introduction [1]: three domains of life; binomial nomenclature; five-kingdom classification; flora status of Nepal
- Fungi
- Lichen
- Algae
- Bryophyta
- Pteridophyta
- Gymnosperm
- Angiosperm [16]: morphology; taxonomic hierarchy; artificial, natural and phylogenetic systems; Brassicaceae; Fabaceae; Solanaceae; Liliaceae
Key points
- Three domains — Archaea, Bacteria, Eukarya — were proposed by Woese (1977) from 16S rRNA sequences. Archaea and Bacteria are prokaryotic; only Archaea have branched, ether-linked membrane lipids.
- Binomial nomenclature (Linnaeus, Species Plantarum, 1753) gives every species a two-word Latin name: capitalised genus, lower-case species epithet, italicised in print, underlined separately in handwriting, governed by the ICN and the principle of priority.
- Whittaker's five kingdoms (1969) — Monera, Protista, Fungi, Plantae, Animalia — separate organisms by cell type, body organisation and mode of nutrition. Viruses fall outside the scheme entirely.
- Nepal holds over 3 % of the world's known plants on 0.1 % of its land: about 6,500 angiosperms, 28 gymnosperms, 534 pteridophytes, 1,150 bryophytes, 771 lichens, with about 300 endemic flowering plants.
- Fungi are achlorophyllous absorptive heterotrophs with chitin walls, glycogen reserve and a mycelium of coenocytic or septate hyphae. Sexual reproduction runs plasmogamy → karyogamy → meiosis, with a dikaryotic stage in the higher classes. Four classes: Phycomycetes (zygospore), Ascomycetes (8 ascospores in an ascus), Basidiomycetes (4 ba
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The syllabus asks for
- Monera
- Virus
- Impacts of biotechnology in microbiology
Key points
- Monera contains all prokaryotes: no nuclear envelope, no membrane-bound organelles, 70S ribosomes, a single naked circular DNA, and a peptidoglycan wall (absent in Mycoplasma, non-peptidoglycan in Archaebacteria).
- Bacterial shapes are coccus, bacillus, vibrio and spiral; the prefixes diplo-, strepto-, staphylo-, tetrad and sarcina name the arrangements.
- Gram-positive walls have thick peptidoglycan and teichoic acid and stain violet; Gram-negative walls have thin peptidoglycan plus an outer lipopolysaccharide membrane and stain pink.
- Reproduction is binary fission (amitosis); endospores are for survival, not reproduction; DNA is exchanged by transformation, conjugation and transduction.
- Population growth is geometric: N = N0 × 2^n with n = t/g.
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The syllabus asks for
- Ecosystem ecology
- Ecological Adaptation
- Ecological Imbalances
Key points
- An ecosystem (Tansley, 1935) has abiotic components (climatic, edaphic, inorganic, organic) and biotic components (producers, consumers, decomposers).
- Food chains are grazing or detritus type; crossing chains form a food web, which gives the ecosystem stability.
- Energy flow is unidirectional: about 1 % of incident light is fixed, and only ~10 % passes from each trophic level to the next (Lindeman's ten per cent law). Matter, in contrast, moves in cycles.
- NPP = GPP - R; standing crop is a mass, productivity is a rate.
- Pyramids of number and of biomass may be inverted; the pyramid of energy is always upright.
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The syllabus asks for
- Vegetation [2]: types of vegetation in Nepal; In-situ and Ex-situ conservation
- Natural environment, vegetation and human activities
Key points
- Vegetation is the plant cover of an area; flora is the list of species in it. Nepal holds about 3.2 % of world flora on under 0.1 % of world land.
- Temperature falls about 6 °C per 1000 m, which produces six altitudinal zones: Tropical (<1000 m, Sal), Subtropical (1000–2000 m, chilaune–katus and chir pine), Temperate (2000–3000 m, oak and rhododendron), Subalpine (3000–4000 m, fir and birch), Alpine (4000–5000 m, scrub and meadow) and Nival (>5000 m, snow).
- The tree line lies near 4000 m. Behind the Himalaya, the trans-Himalayan steppe of Mustang, Manang and Dolpa gets only about 250 mm of rain and carries Caragana, Artemisia and Hippophae.
- In-situ conservation protects the habitat: 13 national parks, 1 wildlife reserve (Koshi Tappu), 1 hunting reserve (Dhorpatan), 6 conservation areas, 13 buffer zones and 10 Ramsar sites — about 23.4 % of the country. Chitwan (1973) was the first; Annapurna (1992) is the largest.
- Ex-situ conservation protects the organism away from its habitat: the National Botanical Garden at Godawari (1962), the National Herbarium (KATH), the National Gene Bank at Khumaltar (2010), community seed banks, and the Central Zoo, Jawalakhel (1932).
- Zoology
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The syllabus asks for
- Introduction to Biology
Key points
- Biology is the science of living organisms; from Greek bios (life) and logos (study), brought into use in 1802 by Treviranus and Lamarck. Aristotle is the Father of Biology and of Zoology; Theophrastus the Father of Botany.
- Living things show cellular organisation, metabolism, growth, reproduction, irritability, homeostasis, adaptation and evolution, and a finite life span.
- Branches divide by the group studied — botany, zoology, microbiology, mycology, phycology, entomology, ichthyology, herpetology, ornithology, parasitology — and by the aspect studied — morphology, anatomy, histology, cytology, physiology, biochemistry, genetics, embryology, taxonomy, evolution, palaeontology, ecology, immunology, patholog
- Biology overlaps physics (biophysics: microscopy, X-ray crystallography, nerve impulses, medical imaging), chemistry (biochemistry: enzymes, respiration, pH), mathematics (biostatistics: Mendelian ratios, Hardy–Weinberg, population models), geology (palaeontology, soils), geography (biogeography) and computing (bioinformatics).
- Total magnification of a compound microscope = eyepiece × objective; real size = image size ÷ magnification. Light microscopes resolve to about 0.2 μm; beyond about 1500× the extra magnification is empty.
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The syllabus asks for
- Life and its Origin
- Evidences of evolution
- Theories of evolution
- Human evolution
Key points
- Life arose once, by chemical evolution under a reducing, oxygen-free atmosphere (Oparin 1924, Haldane 1929): gases → monomers → polymers → protobionts → anaerobic heterotroph → photoautotroph → aerobe. Miller and Urey (1953) obtained amino acids, not life. Pasteur's swan-necked flask had already established biogenesis.
- Homologous organs = same structure, different function → divergent evolution → common ancestry. Analogous = different structure, same function → convergent evolution → adaptation only. Vestigial organs are functionless remnants (appendix, coccyx, plica semilunaris, ear muscles). Early vertebrate embryos share gill slits, notochord and a p
- Fossils are the only direct evidence and include connecting links — Archaeopteryx, lungfish, Peripatus, platypus, Seymouria. Horse series Eohippus → Mesohippus → Merychippus → Pliohippus → Equus: 0.3 → 1.6 m, toes 4 → 1, browsing → grazing teeth.
- Lamarckism (use, disuse, inheritance of acquired characters) was disproved by Weismann's germplasm theory. Darwinism = over-production → struggle → variation → natural selection → new species, but could not explain variation. Neo-Darwinism = mutation + recombination + selection + drift + gene flow + isolation, acting on a population.
- Selection is stabilising, directional or disruptive; industrial melanism in Biston betularia is directional selection recorded in real time.
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The syllabus asks for
- Protista
- Animalia [10]: level of organization; body plan; nine phyla
- Earthworm (Pheretima posthuma)
- Frog (Rana tigrina)
Key points
- Protista holds the eukaryotes that are neither plant, animal nor fungus; the Protozoa are classified by locomotory organelle into Rhizopoda, Mastigophora, Sporozoa and Ciliata.
- Paramecium caudatum is a slipper-shaped ciliate with a pellicle, trichocysts, two contractile vacuoles, a macronucleus and a micronucleus; it swims by a metachronal wave, filter feeds, divides by transverse binary fission and reorganises its nuclei by conjugation.
- Animals are classified by level of organisation, body plan, symmetry, germ layers, coelom and segmentation: Porifera cellular, Coelenterata diploblastic and radial, Platyhelminthes acoelomate, Nemathelminthes pseudocoelomate, Annelida onwards truly coelomate. Chordata is defined by a notochord, a dorsal hollow nerve cord, pharyngeal gill
- Pheretima posthuma has a clitellum on segments 14–16, perichaetine setae, a gizzard, calciferous glands, caeca at segment 26 and a typhlosole, four pairs of hearts in a closed circulation, three kinds of nephridia and a solid ventral nerve cord. It is hermaphrodite but cross-fertilising, with external fertilisation inside the cocoon.
- Rana tigrina breathes cutaneously, buccopharyngeally and through lungs worked by a buccal force pump; its three-chambered heart with a spiral valve gives a double but incomplete circulation. It is ureotelic, with mesonephric kidneys and a shared urinogenital duct in the male; fertilisation is external after amplexus, and thyroxine-driven
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The syllabus asks for
- Animal adaptation
- Animal behavior
- Environmental Pollution
Key points
- Adaptation is an inherited morphological, physiological or behavioural feature that fits an animal to its habitat; acclimatisation, by contrast, is a reversible change within one lifetime.
- A bony fish is adapted by a fusiform body, mucus and scales, paired and unpaired fins, counter-current gills, an air bladder for buoyancy, and osmoregulation that is opposite in fresh and salt water.
- Flight adaptations: streamlined body, feathers, wings, pneumatic bones, keeled sternum, huge pectoral muscles, nine air sacs, four-chambered heart and weight economy (no urinary bladder, uric acid, one ovary).
- Bergmann's rule — colder climate, larger body; Allen's rule — colder climate, shorter extremities.
- Unlimited growth is exponential, dN/dt = rN, Nt = N0e^rt, a J-curve; limited growth is logistic, dN/dt = rN(K-N)/K, an S-curve, fastest at N=K/2 and levelling at the carrying capacity K. Doubling time td = ln 2/r.
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The syllabus asks for
- Conservation Biology
- Wildlife [2]: IUCN categories; endangered species of Nepal
Key points
- Conservation biology is the mission-oriented science of protecting biodiversity; biodiversity exists at genetic, species and ecosystem levels.
- Species diversity combines richness (how many species) and evenness (how equally shared). Simpson: D = Σ ni(ni-1) / N(N-1); diversity is 1-D. Shannon: H = -Σ pi ln pi, with Hmax = ln S and evenness E = H/ln S.
- The drivers of loss are HIPPO: habitat loss, invasive species, pollution, population growth, overexploitation — amplified by climate change.
- Small populations then suffer inbreeding depression, genetic drift, demographic stochasticity and the Allee effect; the MVP is the smallest population with a high chance of long-term survival.
- In-situ conservation protects species in their habitat (parks, reserves, conservation areas, buffer zones); ex-situ conservation protects them outside it (zoos, gene banks, captive breeding). They are complementary.
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The paper
3hr, FM 75 written (+25 internal)
| Section | Questions | Marks each | Total |
|---|---|---|---|
| Section I Botany 37 + Section II Zoology 38 | — | — | — |
Where the hours go
Teaching hours are the board's guide to how much of the paper each part carries.
- Botany64 h
- Zoology64 h