Ans: Biodiversity refers to the variety of living organisms present on Earth, including their species, genes, and ecosystems.

Ans: Carl Linnaeus proposed the system of binomial nomenclature for naming living organisms.

Ans: Species is the basic unit of classification.

Ans: Monera, Protista, Fungi, Plantae, and Animalia are the five kingdoms proposed by R.H. Whittaker.

Ans: Plantae: autotrophic (make own food via photosynthesis), have cell walls, do not move, have chlorophyll. Animalia: heterotrophic (consume other organisms), no cell wall, can move, no chlorophyll.

Ans: Vertebrates: have a backbone (vertebral column), well-developed internal skeleton, e.g., fish, frogs, birds, humans. Invertebrates: lack a backbone, e.g., insects, earthworms, starfish, sponges.

Ans: Plants are classified as: (1) Thallophyta – no differentiated body parts (thallus), e.g., algae like Spirogyra. (2) Bryophyta – have stem and leaf-like structures but no vascular tissue, called amphibians of plant kingdom, e.g., moss, Liverwort. (3) Pteridophyta – have vascular tissue but no seeds, e.g., ferns. (4) Gymnosperms – have naked seeds (not enclosed in fruit), e.g., pine, cycas. (5) Angiosperms – seeds enclosed in fruit (flowering plants); divided into monocots and dicots.

Ans: The basis of classification includes: (1) Cell structure – prokaryotic or eukaryotic, unicellular or multicellular. (2) Mode of nutrition – autotrophic or heterotrophic. (3) Body organisation – presence of tissues, organs, organ systems. (4) Presence of cell wall. (5) Reproduction – sexual or asexual. (6) Evolutionary relationships – organisms that evolved from common ancestors are grouped together (natural classification).

Ans: Major animal phyla: (1) Porifera – pore-bearing, no true tissues, e.g., Sycon (sponge). (2) Coelenterata – hollow body cavity, tentacles with stinging cells, e.g., Hydra, jellyfish. (3) Platyhelminthes – flatworms, bilaterally symmetrical, e.g., tapeworm. (4) Nematoda – roundworms, cylindrical body, e.g., Ascaris. (5) Annelida – segmented worms, e.g., earthworm, leech. (6) Arthropoda – jointed legs, exoskeleton of chitin, largest phylum, e.g., insects, crabs. (7) Mollusca – soft body, usually with shell, e.g., snail, octopus. (8) Echinodermata – spiny skin, water vascular system, e.g., starfish, sea urchin. (9) Chordata – notochord at some stage; includes vertebrates like fish, amphibians, reptiles, birds, and mammals.

Ans: Carolus Linnaeus is called the father of modern taxonomy. He introduced the binomial nomenclature system in 1758 through his book Systema Naturae, giving every organism a two-part Latin scientific name (genus + species).

Ans: Species is the basic unit of classification. Organisms of the same species share common characteristics and are able to interbreed to produce fertile offspring. Homo sapiens is the scientific name of the human species.

Ans: Mushrooms belong to Kingdom Fungi. Characteristic feature: their cell wall is made of chitin (not cellulose). They are heterotrophic, obtaining nutrition by secreting digestive enzymes onto dead matter and absorbing the digested nutrients (saprophytic nutrition).

Ans: Binomial nomenclature is the internationally accepted system of giving each organism a two-part scientific name in Latin, proposed by Carolus Linnaeus. Rules: first word = genus (capital letter); second word = specific epithet (small letter); written in italics or underlined. Scientific names: (1) Human — Homo sapiens, (2) Tiger — Panthera tigris, (3) Mango — Mangifera indica, (4) Housefly — Musca domestica, (5) Potato — Solanum tuberosum, (6) Indian frog — Rana tigrina.

Ans: Gymnosperms: (1) Seeds are naked — not enclosed in a fruit. (2) Flowers absent. (3) Generally evergreen with needle-like leaves. (4) Wood is homoxylous (one type of cell). Examples: Pinus, Cycas, Ginkgo. Angiosperms: (1) Seeds enclosed within a fruit (ovary develops into fruit). (2) Have true flowers. (3) Most diverse plant group; includes trees, shrubs, herbs. (4) Divided into monocots (one cotyledon; e.g., wheat, rice) and dicots (two cotyledons; e.g., mango, pea). Examples: rose, sunflower, mango.

Ans: Bryophyta: (1) No vascular tissue (xylem and phloem absent). (2) Body not differentiated into true roots, stems and leaves — simple thallus-like body. (3) Called the amphibians of the plant kingdom — need water for reproduction. Examples: Funaria (moss), Marchantia. Pteridophyta: (1) Vascular tissue (xylem and phloem) present — first vascular plants. (2) Body differentiated into true roots, stems and leaves. (3) Reproduce by spores but do not produce seeds. Examples: Dryopteris (fern), Equisetum.

Ans: R.H. Whittaker (1969) proposed five kingdoms based on cell structure, body organization and mode of nutrition: (1) Monera — prokaryotes; no nuclear membrane; single-celled; autotrophic or heterotrophic; e.g., Bacteria (E. coli), Cyanobacteria (Nostoc). (2) Protista — unicellular eukaryotes; live in water; some are autotrophic (diatoms), some heterotrophic (Amoeba); e.g., Paramecium, Euglena. (3) Fungi — eukaryotic; heterotrophic (saprophytic/parasitic); cell wall of chitin; no chlorophyll; e.g., Rhizopus (bread mould), Agaricus (mushroom). (4) Plantae — multicellular eukaryotes; autotrophic (photosynthesis); cell wall of cellulose; e.g., fern, rose, mango. (5) Animalia — multicellular eukaryotes; heterotrophic; no cell wall; ingest food; e.g., earthworm, frog, human.

Ans: (1) Pisces (Fish) — aquatic; scales; 2-chambered heart; e.g., Rohu, shark. (2) Amphibia — aquatic and terrestrial; moist glandular skin; 3-chambered heart; e.g., frog, toad. (3) Reptilia — mostly terrestrial; dry, scaly skin; 3-chambered heart (4-chambered in crocodile); cold-blooded; e.g., lizard, snake, turtle. (4) Aves (Birds) — aerial/terrestrial; feathers and scales on legs; 4-chambered heart; warm-blooded; hollow bones; e.g., pigeon, crow. (5) Mammalia — terrestrial/aquatic/aerial; hair/fur; 4-chambered heart; warm-blooded; mammary glands; e.g., bat (aerial), whale (aquatic), human (terrestrial). Cold-blooded (ectotherms): Pisces, Amphibia, Reptilia. Warm-blooded (endotherms): Aves, Mammalia.

Ans: Kingdom Plantae is divided into five major groups based on complexity: (1) Thallophyta (Algae) — simplest plants; body not differentiated (thallus); no vascular tissue; no embryo stage; mostly aquatic; reproduce by spores; e.g., Spirogyra, Ulva, Chara, Sargassum. Significance: produce much of Earth's oxygen. (2) Bryophyta — body differentiated into stem-like and leaf-like parts but no true roots; no vascular tissue; need water for fertilization; amphibians of plant kingdom; e.g., Funaria (moss), Marchantia (liverwort). (3) Pteridophyta — first true vascular plants; have xylem and phloem; true roots, stems and leaves; reproduce by spores (no seeds); e.g., Dryopteris (fern), Equisetum, Marsilea. (4) Gymnosperms — vascular plants; produce naked seeds not enclosed in fruit; mostly evergreen trees; no true flowers; e.g., Pinus (pine), Cycas, Cedrus (deodar). (5) Angiosperms — most evolved; seeds enclosed in fruit; have true flowers; two subgroups: Monocots (1 cotyledon, parallel venation, fibrous root; e.g., maize, rice, onion) and Dicots (2 cotyledons, reticulate venation, tap root; e.g., mango, gram, mustard). Trend of evolution: increasing complexity — from no differentiation to vascular tissue to seeds to enclosed seeds.

Ans: Earthworm — Phylum Annelida: segmented body (metameric segmentation); bilaterally symmetrical; true coelom; closed circulatory system; first animals with true coelom; setae for locomotion; e.g., Lumbricus, Pheretima. Prawn — Phylum Arthropoda: jointed appendages; exoskeleton of chitin; open circulatory system; well-developed head; compound eyes; e.g., Palaemon (prawn), Apis (bee), Anopheles (mosquito). Starfish — Phylum Echinodermata: spiny skin; water vascular system with tube feet; radially symmetrical adults; exclusively marine; regeneration ability; e.g., Asterias, sea urchin. Bat — Phylum Chordata, Class Mammalia: warm-blooded; hair on body; 4-chambered heart; mammary glands; viviparous; forelimbs modified into wings (patagium); only flying mammal; uses echolocation. Frog — Phylum Chordata, Class Amphibia: lives in water and on land; moist, glandular skin; 3-chambered heart; cold-blooded; external fertilization; undergoes metamorphosis (tadpole to adult); e.g., Rana tigrina.