Comprehensive University Biology Study Guide
BIOLOGY UNITS & CHAPTERS OVERVIEW
Unit I: Diversity in the Living World
Chapter 1: The Living World
Chapter 2: Biological Classification
Chapter 3: Plant Kingdom
Chapter 4: Animal Kingdom
Unit II: Structural Organisation in Plants and Animals
Chapter 5: Morphology of Flowering Plants
Chapter 6: Anatomy of Flowering Plants
Chapter 7: Structural Organisation in Animals
Unit III: Cell Structure and Functions
Chapter 8: Cell: The Unit of Life
Chapter 9: Biomolecules
Chapter 10: Cell Cycle and Cell Division
Unit IV: Plant Physiology
Chapter 11: Transport in Plants
Chapter 12: Mineral Nutrition
Chapter 13: Photosynthesis in Higher Plants
Chapter 14: Respiration in Plants
Chapter 15: Plant Growth and Development
Unit V: Human Physiology
Chapter 16: Digestion and Absorption
Chapter 17: Breathing and Exchange of Gases
Chapter 18: Body Fluids and Circulation
Chapter 19: Excretory Products and Their Elimination
Chapter 20: Locomotion and Movement
Chapter 21: Neural Control and Coordination
Chapter 22: Chemical Coordination and Integration
THE LIVING WORLD
Defining "Life" through Characteristics
Growth: Increase in mass and number of individuals are twin characteristics. Multicellular organisms grow by cell division. In plants, growth occurs continuously throughout life; in animals, it occurs only up to a certain age. Non-living objects like mountains grow by accumulation of material on the surface, but in living beings, growth is internal. Therefore, growth alone is not a defining property.
Reproduction: Production of progeny possessing features similar to parents. Methods include sexual and asexual (e.g., fungi via spores, yeast/hydra via budding, Planaria via regeneration). Unicellular organisms equate growth with reproduction. Some living organisms do not reproduce (mules, sterile worker bees, infertile human couples); thus, reproduction is not an all-inclusive defining characteristic.
Metabolism: The sum total of all chemical reactions occurring in the body. All plants, animals, and fungi exhibit metabolism. Isolated metabolic reactions in vitro (test tubes) are not living things but are living reactions. Metabolism is a defining feature without exception.
Consciousness: The ability to sense surroundings/environment and respond to stimuli (physical, chemical, or biological). All organisms from prokaryotes to eukaryotes show consciousness. Humans are the only organisms with "self-consciousness."
Diversity and Taxonomy
Biodiversity: The number and types of organisms on Earth. Currently known species range between million.
Nomenclature: Standardizing the naming of organisms so they are known by the same name worldwide. This requires Identification (correctly describing an organism).
Binomial Nomenclature: System provided by Carolus Linnaeus. Each name has two components: the Generic name (Genus) and the Specific epithet (Species).
Example: Mangifera indica (Mango). Mangifera is the genus, indica is the species.
Rules of Nomenclature:
Names are generally in Latin and written in italics.
First word is Genus (starts with capital), second is Species (starts with small letter).
When handwritten, they are separately underlined.
Author's name appears after the specific epithet in abbreviated form (e.g., Mangifera indica Linn.).
Taxonomic Hierarchy
Classification involves a hierarchy of steps where each step represents a rank or taxon.
Hierarchy Order (Ascending): Species → Genus → Family → Order → Class → Phylum (for animals) or Division (for plants) → Kingdom.
As we go higher from species to kingdom, the number of common characteristics decreases.
Taxonomical Aids
Herbarium: Storehouse of collected plant specimens that are dried, pressed, and preserved on sheets.
Botanical Gardens: Collections of living plants for reference (e.g., Kew, England; NBRI, Lucknow).
Museums: Collections of preserved plant and animal specimens for study (preserved in jars with solutions, as dry specimens, or as skeletons).
Zoological Parks (Zoos): Places where wild animals are kept in protected environments under human care.
Key: Used for identification based on similarities and dissimilarities, usually based on contrasting characters in a pair called a couplet. Each statement in the key is called a lead.
BIOLOGICAL CLASSIFICATION
Historical Background
Aristotle: Earliest to attempt scientific classification. Used morphological characters to classify plants (trees, shrubs, herbs) and animals (those with red blood and those without).
Linnaeus: Two Kingdom system (Plantae and Animalia). Failed to distinguish between eukaryotes/prokaryotes, unicellular/multicellular, and photosynthetic/non-photosynthetic organisms.
R.H. Whittaker (1969): Proposed Five Kingdom Classification based on cell structure, body organization, mode of nutrition, reproduction, and phylogenetic relationships.
Kingdom Monera
Sole members are Bacteria. Occur everywhere (extreme habitats like hot springs, deserts, deep oceans).
Shapes: Coccus (spherical), Bacillus (rod-shaped), Vibrium (comma-shaped), Spirillum (spiral).
Archaebacteria: Live in harshest habitats (Halophiles - salty areas; Thermoacidophiles - hot springs; Methanogens - marshy areas). Methanogens are found in the gut of ruminants and produce methane (biogas).
Eubacteria ("True bacteria"): Rigid cell wall and motile flagellum. Includes Cyanobacteria (Blue-green algae), which are photosynthetic autotrophs with chlorophyll a. Some can fix atmospheric nitrogen in specialized cells called heterocysts (e.g., Nostoc, Anabaena).
Mycoplasma: Organisms that completely lack a cell wall. Smallest living cells known; can survive without oxygen; many are pathogenic.
Kingdom Protista
All single-celled eukaryotes. Primarily aquatic. Contains a well-defined nucleus and membrane-bound organelles.
Chrysophytes: Diatoms and golden algae (desmids). Found in fresh and marine water. Diatoms have indestructible silica cell walls that form "diatomaceous earth," used in polishing and filtration.
Dinoflagellates: Mostly marine and photosynthetic. Vary in color. Often show rapid multiplication (e.g., Gonyaulax) causing "red tides."
Euglenoids: Fresh water organisms. Instead of a cell wall, they have a protein-rich layer called pellicle making the body flexible. Photosynthetic in sunlight but heterotrophic when deprived.
Slime Moulds: Saprophytic protists. In suitable conditions, they form an aggregation called plasmodium.
Protozoans: Heterotrophs (predators or parasites). Includes Amoeboid (e.g., Entamoeba), Flagellated (e.g., Trypanosoma - causes sleeping sickness), Ciliated (e.g., Paramoecium), and Sporozoans (e.g., Plasmodium - causes malaria).
Kingdom Fungi
Heterotrophic organisms. Cell walls composed of chitin and polysaccharides.
Structure: Long, slender thread-like structures called hyphae. A network of hyphae is a mycelium. Some hyphae are continuous tubes filled with multinucleated cytoplasm (coenocytic hyphae).
Reproduction: Vegetative (fragmentation, fission, budding); Asexual (spores: conidia, sporangiospores, zoospores); Sexual (oospores, ascospores, basidiospores).
Classes:
Phycomycetes: Found in aquatic habitats and on decaying wood. Mycelium is aseptate and coenocytic (e.g., Mucor, Rhizopus).
Ascomycetes (Sac-fungi): Mostly multicellular (e.g., Penicillium) or unicellular (e.g., Yeast). Mycelium is branched and septate.
Basidiomycetes: Mushrooms, bracket fungi, puffballs. Mycelium branched and septate. Asexual spores usually not found (e.g., Agaricus, Ustilago, Puccinia).
Deuteromycetes (Imperfect fungi): Only asexual or vegetative phases are known. Once sexual stages are found, they are moved to proper classes (e.g., Alternaria, Colletotrichum, Trichoderma).
Viruses, Viroids, Prions, and Lichens
Viruses: Non-cellular organisms with an inert crystalline structure outside living cells. Obligate parasites. Contain genetic material (RNA or DNA—never both). Protein coat called capsid made of small subunits called capsomeres protects nucleic acid.
Viroids: Smaller than viruses; consist only of free RNA without a protein coat. Discovered by T.O. Diener (1971).
Lichens: Symbiotic associations between Algae (phycobiont - autotrophic) and Fungi (mycobiont - heterotrophic). Bio-indicators of pollution (they do not grow in polluted areas).
PLANT KINGDOM
Algae
Chlorophyll-bearing, simple, thalloid, autotrophic, largely aquatic organisms.
Chlorophyceae (Green Algae): Pigments Chlorophyll a and b. Food stored in pyrenoids (starch and protein). Cell wall: inner cellulose, outer pectose (e.g., Volvox, Chlamydomonas).
Phaeophyceae (Brown Algae): Pigments Chlorophyll a, c, carotenoids, and xanthophylls (fucoxanthin). Food stored as complex carbohydrates (Laminarin/Mannitol). Cell wall covered by algin (e.g., Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus).
Rhodophyceae (Red Algae): Pigment r-phycoerythrin. Food stored as floridean starch (similar to amylopectin and glycogen) (e.g., Polysiphonia, Porphyra, Gracilaria, Gelidium).
Bryophytes ("Amphibians of the plant kingdom")
Live in soil but depend on water for sexual reproduction. Thallus-like body, attached by rhizoids.
Liverworts: Thalloid body (e.g., Marchantia). Asexual reproduction via fragmentation or gemmae (green, multicellular buds).
Mosses: Gametophyte consists of two stages: Protonema (creeping, green, branched) and Leafy stage (upright, slender axis with spiral leaves). Examples: Funaria, Polytrichum, Sphagnum.
Pteridophytes
Used for medicinal purposes and as soil-binders. First terrestrial plants to possess vascular tissues (xylem and phloem). Sporophyte is the dominant phase, differentiated into true roots, stem, and leaves.
Leaves may be small (microphylls, e.g., Selaginella) or large (macrophylls, e.g., ferns). Sporangia produce spores by meiosis. Most are homosporous, but some are heterosporous (e.g., Selaginella, Salvinia).
Gymnosperms
Plants in which ovules are not enclosed by an ovary wall and remain exposed. Includes medium to tall trees (e.g., Sequoia - giant redwood). Many have mycorrhizal associations (Pinus) or coralloid roots (Cycas).
Heterosporous: produce haploid microspores and megaspores. Development of pollen tubes and seeds occur, but seeds are "naked."
Angiosperms (Flowering Plants)
Pollen grains and ovules are developed in specialized structures called flowers. Seeds are enclosed in fruits. Divided into Dicotyledons (two cotyledons) and Monocotyledons (one cotyledon).
Double Fertilization: Unique to angiosperms. One male gamete fuses with the egg (Syngamy) to form a Zygote (). The other male gamete fuses with the diploid secondary nucleus to produce Triploid Primary Endosperm Nucleus (PEN).
ANIMAL KINGDOM
Basis of Classification
Levels of Organisation: Cellular (Sponges), Tissue (Coelenterates), Organ (Platyhelminthes), Organ System (Annelids to Chordates).
Symmetry: Asymmetrical (Sponges), Radial (Coelenterates, Ctenophores, Echinoderms), Bilateral (Annelids, Arthropods, etc.).
Diploblastic vs. Triploblastic: Diploblastic have ectoderm and endoderm; Triploblastic have a third germinal layer, mesoderm.
Coelom: Body cavity lined by mesoderm. Acoelomates (lack cavity), Pseudocoelomates (mesoderm in scattered pouches), Coelomates (true body cavity).
Segmentation: Serially repeated segments (metamerism), seen in earthworms.
Notochord: Mesodermally derived rod-like structure (Chordates vs. Non-chordates).
Classification of Phyla
Porifera (Sponges): Cellular level; canal system with choanocytes (collar cells); internal skeletons (spicules/spongin fibers).
Coelenterata (Cnidaria): Presence of cnidoblasts (stinging cells) on tentacles. Two forms: Polyp (sessile) and Medusa (free-swimming). Metagenesis (alternation of generations) seen in Obelia.
Ctenophora (Sea walnuts): Exclusively marine; eight rows of ciliated comb plates; exhibit bioluminescence.
Platyhelminthes (Flatworms): Dorso-ventrally flattened; acoelomate; flame cells for excretion (e.g., Taenia, Fasciola).
Aschelminthes (Roundworms): Pseudocoelomate; alimentary canal with muscular pharynx; dioecious (e.g., Ascaris, Wuchereria).
Annelida: Segmented; closed circulatory system; nephridia for excretion (e.g., Nereis, Earthworm, Leech).
Arthropoda: Largest phylum; jointed appendages; chitinous exoskeleton; Malpighian tubules for excretion (e.g., Apis, Anopheles, Locusta).
Mollusca: Second largest phylum; soft body with calcareous shell; mantle cavity with gills; radula for feeding (e.g., Pila, Octopus).
Echinodermata: Spiny skinned; water vascular system; radial symmetry in adults, bilateral in larvae (e.g., Asterias, Echinus).
Hemichordata: Worm-like marine animals; proboscis, collar, and trunk (e.g., Balanoglossus).
Chordata: Differentiated by notochord, dorsal hollow nerve cord, and paired pharyngeal gill slits.
Vertebrata Classes
Cyclostomata: Jawless; ectoparasites on fishes; circular mouth.
Chondrichthyes: Cartilaginous endoskeleton; placoid scales; powerful jaws (e.g., Scoliodon, Pristis).
Osteichthyes: Bony endoskeleton; four pairs of gills covered by operculum; air bladder (e.g., Labeo, Exocoetus).
Amphibia: Can live in aquatic and terrestrial habitats; skin is moist; 3-chambered heart (e.g., Rana, Hyla).
Reptilia: Creeping/cravling mode of locomotion; dry cornified skin; mostly 3-chambered heart (Crocodiles have 4).
Aves (Birds): Presence of feathers; forelimbs modified into wings; pneumatic (hollow) bones; 4-chambered heart.
Mammalia: Mammary glands present; skin with hair; 2 pairs of limbs; 4-chambered heart.
MORPHOLOGY & ANATOMY OF FLOWERING PLANTS
Roots: Tap root system (Dicots), Fibrous root system (Monocots), Adventitious roots (from parts other than radicle). Regions: Root cap, Meristematic zone, Elongation zone, Maturation zone. Modifications: Storage (carrot), Support (Prop roots of banyan, Stilt roots of maize), Respiration (Pneumatophores in Rhizophora).
Stem: Develops from plumule; contains nodes and internodes. Modifications: Food storage (potato, ginger), Tendrils (climbing), Thorns (protection), Photosynthetic (flattened in Opuntia).
Leaf: Parts include leaf base, petiole, and lamina. Venation is Reticulate (Dicots) or Parallel (Monocots). Leaves are Simple or Compound (Pinnate/Palmate). Phyllotaxy (arrangement): Alternate, Opposite, Whorled.
Inflorescence & Flower: Inflorescence: Racemose (continuous growth) or Cymose (limited growth). Flower symmetry: Actinomorphic (radial), Zygomorphic (bilateral). Ovary position: Hypogynous (superior), Perigynous (half-inferior), Epigynous (inferior).
Tissue Systems:
Epidermal: Outermost covering (epidermis, stomata, hairs/trichomes).
Ground: Bulk of the plant (parenchyma, collenchyma, sclerenchyma). Mesophyll in leaves.
Vascular: Xylem and Phloem. Arranged as Radial (roots) or Conjoint (stems/leaves). Open bundles have cambium; closed do not.
BIOMOLECULES
Analysis: Living tissues analyzed using trichloroacetic acid () to yield acid-soluble pool (micromolecules) and acid-insoluble fraction (macromolecules).
Amino Acids: Organic compounds containing amino group and acidic group on the same carbon (-carbon). 20 types occur in proteins.
Proteins: Polypeptides; heteropolymers of amino acids. Collagen is the most abundant protein in the animal world; RuBisCO in the whole biosphere.
Polysaccharides: Long chains of sugars. Starch (plant energy store), Glycogen (animal energy store), Cellulose (plant cell walls).
Nucleic Acids: DNA and RNA. Building blocks are nucleotides (sugar + nitrogenous base + phosphate).
CELL CYCLE & DIVISION
Interphase: Phase between two successive M phases.
: Cell metabolically active, grows but does not replicate DNA.
: DNA synthesis/replication occurs.
: Proteins synthesized for mitosis.
Mitosis (Equational division): Occurs in somatic cells. Stages: Prophase, Metaphase (chromosomes align at equator), Anaphase (chromatids separate), Telophase (nuclear envelope reforms). Cytokinesis follows.
Meiosis (Reduction division): Reduces chromosome number by half.
Meiosis I: Homologous chromosomes pair up and exchange genetic material (Crossing over in Pachytene).
Meiosis II: Regular mitotic division.
PLANT PHYSIOLOGY
Transport: Short distance (diffusion, cytoplasmic streaming) and long distance (translocation via xylem and phloem).
Photosynthesis: Physico-chemical process using light energy to drive organic compound synthesis. Occurs in chloroplasts. Light reaction occurs in thylakoids (grana); dark reaction in stroma. C3 Pathway (Calvin cycle) and C4 Pathway (Hatch-Slack).
Respiration: Breakdown of C-C bonds of complex molecules. Glycolysis occurs in cytoplasm. Aerobic respiration follows via Kreb's Cycle (matrix) and ETS (inner mitochondrial membrane).
HUMAN PHYSIOLOGY
Digestion: Breakdown of complex food. Alimentary canal includes mouth (teeth - thecodont, diphyodont, heterodont), stomach (J-shaped), and intestines. Principal enzymes: Amylases, Proteases (pepsin, trypsin), Lipases.
Breathing: Oxygen () intake and Carbon dioxide () release. Transport of gases via hemoglobin in RBCs.
Excretion: Kidney is the primary organ. Functional unit is the Nephron (Glomerulus + Renal tubule). Urine formation involves filtration, reabsorption, and secretion.
Neural Coordination: Nerve impulse transmission via neurons. Central Nervous System (Brain and Spinal Cord) and Peripheral Nervous System (Somatic and Autonomic).