प्राणीशास्त्र Zoology

थोडक्यात सारांश

Classification means arranging animals into groups based on their similarities and differences. It makes the study of millions of animals easy. This topic covers the basis of classification, binomial nomenclature, taxonomic hierarchy and the outline classification of the animal kingdom (non-chordates and chordates).

महत्त्वाचे मुद्दे

• Carolus Linnaeus is the father of taxonomy. He introduced binomial nomenclature in Systema Naturae (10th edition, 1758).
• In binomial nomenclature each animal has two names: genus (capital first letter) and species (small letter), printed in italics or underlined separately when handwritten. Example: Panthera tigris (tiger), Homo sapiens (human).
• R. H. Whittaker (1969) gave the five-kingdom classification: Monera, Protista, Fungi, Plantae, Animalia.
• Taxonomic hierarchy (वर्गीकरण श्रेणी): Kingdom → Phylum → Class → Order → Family → Genus → Species.
• Species is the basic unit of classification: a group of similar individuals that can interbreed and produce fertile offspring.
• Basis of classification: levels of organisation, symmetry, germ layers, body cavity (coelom), segmentation and notochord.
• Levels of organisation: cellular (Porifera), tissue (Cnidaria), organ (Platyhelminthes), organ-system (higher phyla).
• Symmetry: asymmetrical (most sponges), radial (Cnidaria, adult Echinodermata), bilateral (most other phyla).
• Germ layers: diploblastic (ectoderm and endoderm – Cnidaria) and triploblastic (with mesoderm – Platyhelminthes onwards).
• Coelom: acoelomate (Platyhelminthes), pseudocoelomate (Aschelminthes), coelomate/eucoelomate (Annelida onwards).
• Non-chordates lack a notochord; chordates have a notochord, a dorsal hollow nerve cord and pharyngeal gill slits at some stage.

महत्त्वाच्या संज्ञा

• Taxon – any unit of classification (e.g. a family or a genus).
• Coelom – fluid-filled body cavity lined by mesoderm on both sides.
• Pseudocoelom – body cavity not fully lined by mesoderm.
• Metamerism – division of body into similar segments (e.g. earthworm).
• Protostome – mouth forms from blastopore (Annelida, Arthropoda, Mollusca).
• Deuterostome – anus forms from blastopore (Echinodermata, Chordata).

महत्त्वाची माहिती

५ महत्त्वाचे प्रश्न

Q1. What is binomial nomenclature?

It is the system of naming every organism by two words: genus name and species name. It was introduced by Linnaeus. Example: Rana tigrina (Indian bullfrog; now also named Hoplobatrachus tigerinus).

Q2. Differentiate between diploblastic and triploblastic animals.

Diploblastic animals have two germ layers, ectoderm and endoderm, with a non-cellular mesoglea between them (e.g. Hydra). Triploblastic animals have three germ layers including mesoderm (e.g. earthworm, human).

Q3. Explain the taxonomic hierarchy with an example.

• Arrange the seven main ranks from kingdom to species.
• Each higher rank includes several lower ranks.
• Example (human): Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Primates, Family Hominidae, Genus Homo, Species sapiens.
• Lower ranks show more similarity among members.

Q4. Describe the basis of classification of animals.

• Level of organisation (cellular to organ-system).
• Symmetry (asymmetry, radial, bilateral).
• Germ layers (diploblastic, triploblastic).
• Coelom (acoelomate, pseudocoelomate, coelomate).
• Segmentation and notochord.
• Give one example for each.

Q5. Write an outline classification of non-chordates with one example each.

• List the nine phyla from Protozoa to Echinodermata.
• Give one key character and one Indian example for each (as in the table).
• Mention that Hemichordata (Balanoglossus) was once placed with chordates but is now often treated separately.

परीक्षेसाठी टीप

Learn the table of phyla with one character and one example. Write scientific names correctly: genus capitalised, species small, both in italics or underlined.

थोडक्यात सारांश

Protozoa are microscopic, unicellular, eukaryotic animal-like organisms. A single cell does all life functions: feeding, movement, respiration, excretion and reproduction. In the five-kingdom system they are placed in Kingdom Protista. This topic covers general characters, classification by locomotion, type study and diseases.

महत्त्वाचे मुद्दे

• Protozoa means "first animals" (प्रोटोझोआ / आदिजीव). The term was given by Goldfuss (1818).
• They are found in fresh water, sea water, moist soil and as parasites in other animals.
• Body is a single cell, but it shows division of labour among its organelles (protoplasmic level of organisation).
• Body may be naked (Amoeba) or covered by a pellicle (Paramecium, Euglena) or a shell/test (Arcella, foraminiferans).
• Locomotion is by pseudopodia, flagella or cilia; parasitic forms may have no locomotor organs.
• Nutrition: holozoic (Amoeba), holophytic (Euglena in light), saprozoic, or parasitic (Plasmodium).
• Contractile vacuoles remove excess water (osmoregulation) in fresh-water forms.
• Respiration and excretion occur by diffusion through the body surface.
• Asexual reproduction: binary fission, multiple fission, budding.
• Sexual reproduction: syngamy and conjugation (Paramecium).
• Many form cysts to survive bad conditions.

महत्त्वाच्या संज्ञा

• Pseudopodia – temporary finger-like projections of cytoplasm (false feet).
• Pellicle – thin, firm, flexible outer covering.
• Macronucleus – large nucleus controlling daily metabolism (Paramecium).
• Micronucleus – small nucleus involved in reproduction.
• Trichocysts – defensive organelles below the pellicle of Paramecium.
• Sporozoite – infective stage of Plasmodium injected by mosquito.
• Schizogony – asexual multiple fission of Plasmodium in human cells.

महत्त्वाची माहिती

• Plasmodium vivax causes benign tertian malaria; female Anopheles mosquito is the vector.
• Ronald Ross (1897) showed the malaria parasite's development in the mosquito; Nobel Prize 1902.
• Entamoeba histolytica causes amoebic dysentery; Trypanosoma gambiense causes sleeping sickness (tsetse fly vector); Leishmania donovani causes kala-azar (sand fly vector).

५ महत्त्वाचे प्रश्न

Q1. What are contractile vacuoles?

They are clear, fluid-filled vacuoles in fresh-water protozoa. They collect excess water from the cytoplasm and throw it out, maintaining water balance (osmoregulation).

Q2. Why is Euglena called a plant-animal?

Euglena has chloroplasts and makes food by photosynthesis like plants. It also has a flagellum, no cell wall and can feed saprozoically in darkness like animals.

Q3. Describe the life cycle of Plasmodium vivax.

• Two hosts: human (intermediate host, asexual) and female Anopheles (definitive host, sexual).
• Mosquito bite injects sporozoites → liver cells (pre-erythrocytic schizogony).
• Merozoites enter RBCs → trophozoite → signet ring → schizont → RBCs burst every 48 hours (fever with chills).
• Some form gametocytes, taken up by mosquito.
• In mosquito: gametes fuse → ookinete → oocyst on stomach wall → sporozoites reach salivary glands.

Q4. Describe conjugation in Paramecium.

• Two individuals of compatible mating types join at the oral groove.
• Macronucleus degenerates; micronucleus divides by meiosis into four; three degenerate.
• The remaining one divides into a stationary and a migratory pronucleus.
• Migratory pronuclei are exchanged and fuse to form a synkaryon.
• Conjugants separate; further divisions restore normal nuclei.
• It brings genetic variation and rejuvenation.

Q5. Give the general characters of Protozoa.

• Unicellular, microscopic, eukaryotic.
• Free-living or parasitic.
• Locomotion by pseudopodia, flagella or cilia.
• Nutrition holozoic, holophytic, saprozoic or parasitic.
• Contractile vacuoles; diffusion for respiration and excretion.
• Asexual and sexual reproduction; encystment.

परीक्षेसाठी टीप

The Plasmodium life cycle is the most-asked question. Write it in two clear parts: in man and in mosquito, with all stage names.

थोडक्यात सारांश

Porifera are sponges – simple, mostly marine, sedentary animals with many pores on the body. They are multicellular but have no true tissues or organs. Water flows through a special canal system for food, respiration and excretion. This topic covers characters, canal system, skeleton, reproduction and examples.

महत्त्वाचे मुद्दे

• The name Porifera means "pore-bearing". The phylum name was given by Robert Grant.
• Sponges (स्पंज) are mostly marine; a few are fresh-water (Spongilla).
• They are sessile (fixed) and mostly asymmetrical; some are radially symmetrical (Sycon).
• Cellular level of organisation; no true tissues.
• Body wall has an outer pinacoderm and an inner choanoderm, with jelly-like mesenchyme (mesohyl) between them.
• Choanocytes (collar cells) line the inner cavities; their flagella create water current and they trap food.
• Water enters through small pores called ostia, passes through the spongocoel or canals, and leaves through a large opening called the osculum.
• Skeleton is made of spicules (calcareous or siliceous) and/or spongin fibres.
• Digestion is intracellular.
• No nervous, respiratory, excretory or circulatory systems.
• Reproduction: asexual by budding and gemmules (internal buds in fresh-water sponges); sexual by gametes. Most are hermaphrodite. Development includes a free-swimming larva (amphiblastula or parenchymula).
• Very high regeneration power.

महत्त्वाच्या संज्ञा

• Ostia – small inhalant pores.
• Osculum – large exhalant opening.
• Spongocoel – central cavity of the sponge.
• Choanocyte – flagellated collar cell.
• Porocyte – tubular cell forming an ostium (in simple sponges).
• Amoebocytes / archaeocytes – wandering cells in mesenchyme; form other cells.
• Gemmule – asexual reproductive body of fresh-water sponges that survives bad conditions.

महत्त्वाची माहिती

• Classes: Calcarea (calcareous spicules – Sycon, Leucosolenia), Hexactinellida (six-rayed siliceous spicules – Euplectella, Venus's flower basket), Demospongiae (siliceous spicules and/or spongin – Spongilla, Euspongia bath sponge).

५ महत्त्वाचे प्रश्न

Q1. What are choanocytes?

Choanocytes are flagellated cells with a collar of microvilli around the flagellum. They line the spongocoel or flagellated chambers, create water current and trap food particles.

Q2. What is a gemmule?

A gemmule is an internal bud formed in fresh-water sponges like Spongilla. It is a group of archaeocytes covered by a protective coat with spicules. It survives drought and cold and grows into a new sponge.

Q3. Describe the canal system in sponges.

• Function: water current for food, oxygen and removal of waste.
• Ascon type: simplest; spongocoel lined by choanocytes.
• Sycon type: body wall folded; radial canals lined by choanocytes.
• Leucon type: most complex; choanocytes in small flagellated chambers.
• Draw the water path for each type.

Q4. Give the general characters of Porifera.

• Aquatic, sessile, mostly marine.
• Asymmetrical or radial; cellular level.
• Ostia, osculum and canal system; choanocytes.
• Spicules or spongin skeleton.
• Intracellular digestion; no organ systems.
• Budding, gemmules, sexual reproduction; high regeneration.

Q5. Describe the structure of Sycon with a labelled diagram.

• Vase-like body fixed at the base; osculum at top surrounded by a fringe of spicules.
• Body wall folded into radial and incurrent canals.
• Pinacoderm outside, choanocytes in radial canals, mesenchyme with spicules and amoebocytes.
• Labels: osculum, spongocoel, ostia, incurrent canal, radial canal, prosopyle, apopyle, spicules, choanocytes.

परीक्षेसाठी टीप

The canal system is a favourite long question. Remember the order of water flow, and that water always leaves through the osculum.

थोडक्यात सारांश

Cnidaria (also called Coelenterata) are aquatic, mostly marine, radially symmetrical animals with stinging cells called cnidocytes. They are the first animals with a tissue level of organisation and a single body cavity (gastrovascular cavity) with one opening. This topic covers characters, body forms, polymorphism, type study of Obelia and corals.

महत्त्वाचे मुद्दे

• The name comes from cnidoblasts/cnidocytes (stinging cells). The older name Coelenterata was given by Leuckart (1847).
• Mostly marine; Hydra is a common fresh-water example.
• Radial symmetry; diploblastic – outer ectoderm (epidermis) and inner endoderm (gastrodermis) with non-cellular mesoglea between.
• Tissue level of organisation.
• Single cavity called the gastrovascular cavity (coelenteron) with one opening, the mouth, surrounded by tentacles.
• Digestion is both extracellular and intracellular.
• Cnidocytes with nematocysts are present on tentacles for defence and capturing prey.
• Nerve net is the simplest nervous system; no brain.
• Two body forms: polyp (cylindrical, fixed, asexual) and medusa (umbrella-like, free-swimming, sexual).
• Metagenesis (alternation of generations): polyp produces medusae asexually; medusae produce polyps through gametes and a planula larva (e.g. Obelia).
• Polymorphism: different forms of individuals in one colony (e.g. Physalia – Portuguese man-of-war).

महत्त्वाच्या संज्ञा

• Nematocyst – capsule inside a cnidocyte with a coiled thread that shoots out to sting or hold prey.
• Hypostome – conical raised region around the mouth.
• Planula – ciliated, free-swimming larva of cnidarians.
• Velum – shelf-like inner fold at the margin of a hydromedusa.
• Manubrium – tube hanging from the medusa carrying the mouth.
• Coral reef – large structure built from calcium carbonate skeletons of coral polyps.

महत्त्वाची माहिती

• ***Obelia*: colonial marine hydroid. Colony has a horizontal hydrorhiza and upright hydrocaulus. It bears two kinds of polyps: feeding gastrozooids (hydranths) and reproductive blastostyles (gonangia) that bud off medusae. Polyps covered by a chitinous perisarc**.
• Coral reefs in India: Gulf of Kutch, Gulf of Mannar, Lakshadweep, Andaman and Nicobar Islands.
• Types of reefs (Darwin's classification): fringing reef, barrier reef, atoll.

५ महत्त्वाचे प्रश्न

Q1. What is a nematocyst?

A nematocyst is a stinging capsule inside a cnidocyte. It contains a coiled hollow thread and poison. On touch, the thread shoots out to paralyse prey or for defence.

Q2. Define metagenesis.

Metagenesis is the regular alternation of an asexual polyp generation and a sexual medusa generation in the life cycle of some cnidarians, such as Obelia.

Q3. Describe the structure and life cycle of Obelia.

• Fixed colony: hydrorhiza, hydrocaulus, branches with hydranths and blastostyles.
• Perisarc forms hydrotheca and gonotheca.
• Blastostyle buds off free medusae.
• Medusae are dioecious; gametes fuse in water.
• Zygote → planula larva → settles → new polyp colony.
• Labels: hydranth, hydrotheca, tentacles, hypostome, blastostyle, gonotheca, medusa bud, perisarc, coenosarc.

Q4. Explain polymorphism in Cnidaria.

• Presence of more than one type of individual in a species for division of labour.
• Dimorphic: gastrozooids and blastostyles (Obelia).
• Polymorphic: Physalia has pneumatophore (float), dactylozooids (defence), gastrozooids (feeding) and gonozooids (reproduction).
• It increases efficiency of the colony.

Q5. Write a note on coral reefs.

• Formed by calcareous skeletons of anthozoan polyps over long time.
• Need warm, clear, shallow sea water.
• Types: fringing, barrier and atoll.
• Importance: rich biodiversity, protect coasts, tourism, source of lime.
• Threats: pollution, coral bleaching due to rising sea temperature, mining.
• Indian reef areas as listed above.

परीक्षेसाठी टीप

Draw Obelia colony and medusa together and mention metagenesis. Remember "diploblastic with mesoglea" as a key character.

थोडक्यात सारांश

Platyhelminthes are flatworms: dorsoventrally flattened, triploblastic, acoelomate animals, many of them parasites. Aschelminthes (Nemathelminthes or Nematoda) are roundworms: cylindrical, unsegmented and pseudocoelomate. This topic covers characters, examples, parasitic adaptations and the life cycles of liver fluke, tapeworm and Ascaris.

महत्त्वाचे मुद्दे

• Platyhelminthes (चपटे कृमी): bilaterally symmetrical, triploblastic, acoelomate; first animals with organ level of organisation.
• Body flat like a leaf or ribbon; digestive system incomplete (one opening) or absent (tapeworm).
• Excretion by flame cells (protonephridia).
• Mostly hermaphrodite (monoecious); fertilisation internal.
• Parasitic forms have hooks, suckers and a thick tegument.
• Classes: Turbellaria (Planaria, free-living, high regeneration), Trematoda (flukes – Fasciola hepatica), Cestoda (tapeworms – Taenia solium).
• Aschelminthes (गोल कृमी): body round, unsegmented, tapering at both ends; covered by a tough cuticle.
• Pseudocoelom present; digestive tract complete (mouth and anus).
• Sexes are separate (dioecious); male usually smaller with a curved tail. Sexual dimorphism is seen.
• No circular muscles; only longitudinal muscles, so movement is whip-like.
• Examples: Ascaris lumbricoides (roundworm), Wuchereria bancrofti (filarial worm), Enterobius (pinworm), Ancylostoma (hookworm).

महत्त्वाच्या संज्ञा

• Flame cell – excretory cell with a tuft of beating cilia like a flickering flame.
• Scolex – head of tapeworm with hooks and suckers.
• Proglottids – segments of tapeworm body; mature ones have both sex organs.
• Strobilisation – formation of proglottids behind the neck.
• Cysticercus – bladder-worm larval stage of Taenia in pig muscle.
• Intermediate host – host in which larval stages develop.
• Pseudocoelom – cavity between body wall and gut not lined by mesoderm on the gut side.

महत्त्वाची माहिती

• Fasciola larval stages (in order): miracidium → sporocyst → redia → cercaria → metacercaria.
• Ascaris has a single host; larvae migrate through liver, heart and lungs before settling in the intestine.

५ महत्त्वाचे प्रश्न

Q1. What are flame cells?

Flame cells are excretory cells of flatworms. Each cell has a cavity with a bunch of cilia whose beating looks like a flame. They push waste fluid into excretory canals.

Q2. Give two differences between Platyhelminthes and Aschelminthes.

Platyhelminthes are flat, acoelomate and mostly hermaphrodite with an incomplete gut. Aschelminthes are round, pseudocoelomate and dioecious with a complete gut.

Q3. Describe the life cycle of Taenia solium.

• Adult in human small intestine, fixed by scolex.
• Gravid proglottids with eggs pass out with faeces.
• Pig eats eggs → onchosphere (hexacanth embryo) hatches → reaches muscles.
• Forms cysticercus (bladder worm) – "measly pork".
• Man eats undercooked pork → cysticercus becomes adult.
• Labels for scolex diagram: rostellum, hooks, suckers, neck.

Q4. Explain parasitic adaptations of helminths.

• Organs of attachment: hooks, suckers.
• Thick tegument/cuticle resists host enzymes.
• Reduced or absent digestive system (tapeworm absorbs digested food).
• Anaerobic respiration.
• Hermaphroditism and huge egg production.
• Larval stages in intermediate hosts; resistant egg shells.

Q5. Describe the life cycle of Ascaris lumbricoides.

• Monogenetic; lives in human small intestine.
• Fertilised eggs pass out in faeces; develop in soil to infective stage.
• Swallowed with food/water; larvae hatch in intestine.
• Migrate via blood to liver, heart, lungs; moult; travel up trachea; swallowed again.
• Mature in intestine; cause ascariasis, malnutrition, intestinal blockage.

परीक्षेसाठी टीप

Learn larval stages of Fasciola in correct order and the hosts of each parasite. A table of parasites and diseases gives quick marks.

थोडक्यात सारांश

The physical environment of animals has three parts: the atmosphere (air), the hydrosphere (water) and the lithosphere (rocks and soil). Life exists where these three meet, in the biosphere. This topic covers the layers and composition of air, the distribution and properties of water, soil formation and erosion, and renewable and non-renewable energy sources.

महत्त्वाचे मुद्दे

• Atmosphere is the envelope of gases around the Earth, held by gravity. Its layers from the ground up are troposphere, stratosphere, mesosphere, thermosphere and exosphere.
• Troposphere (up to about 8–18 km) has nearly all water vapour and weather; temperature falls with height.
• Stratosphere (up to about 50 km) contains the ozone layer, which absorbs harmful ultraviolet (UV) rays.
• Composition of dry air (by volume): nitrogen about 78%, oxygen about 21%, argon about 0.93%, carbon dioxide about 0.04%, plus traces of other gases.
• Hydrosphere covers about 71% of the Earth's surface. About 97% of all water is salty sea water; only about 3% is fresh, and most of that is locked in ice caps and glaciers.
• Physico-chemical characters of water: temperature, colour, turbidity, pH, dissolved oxygen (DO), free CO₂, hardness, alkalinity and nutrients. These decide which animals can live in it.
• Water has a high specific heat and is densest at 4 °C, so ponds freeze from the top and aquatic life survives below.
• Lithosphere is the solid outer crust. Soil forms from rock by weathering (physical, chemical and biological) plus the addition of humus. This process is called pedogenesis.
• Soil erosion is the removal of the top fertile soil by water and wind. Causes: deforestation, overgrazing, faulty farming, mining and floods.
• Renewable energy (solar, wind, hydro, tidal, geothermal, biomass) is replaced naturally. Non-renewable energy (coal, petroleum, natural gas, nuclear fuel) is limited and takes millions of years to form.

महत्त्वाच्या संज्ञा

• Biosphere – the part of Earth where life exists (जीवावरण).
• Ozone layer – layer of O₃ in the stratosphere that filters UV radiation.
• Dissolved oxygen (DO) – amount of oxygen dissolved in water, in mg/L.
• Hardness of water – caused mainly by calcium and magnesium salts.
• Humus – dark, decomposed organic matter in soil.
• Soil profile – vertical section of soil showing layers (horizons O, A, B, C).
• Fossil fuels – coal, oil and gas formed from ancient buried organisms.

महत्त्वाची माहिती

• Good-quality fresh water for fish usually has DO above 5 mg/L and pH about 6.5–8.5.
• Soil conservation methods: afforestation, contour ploughing, terrace farming, strip cropping, check dams, controlled grazing.

५ महत्त्वाचे प्रश्न

Q1. What is the importance of the ozone layer?

The ozone layer in the stratosphere absorbs most of the harmful ultraviolet rays of the Sun. Without it, UV rays would cause skin cancer, cataract, damage to crops and harm to aquatic life.

Q2. Distinguish between renewable and non-renewable energy sources.

Renewable sources (solar, wind, hydro, biomass) are replaced naturally and do not run out; they cause little pollution. Non-renewable sources (coal, petroleum, natural gas) are limited, take millions of years to form and cause pollution when burnt.

Q3. Describe the major zones of the atmosphere and the composition of air.

• Define atmosphere.
• Five zones with height and features (table above).
• Composition: N₂ 78%, O₂ 21%, Ar 0.93%, CO₂ 0.04%, water vapour variable.
• Importance: oxygen for respiration, CO₂ for photosynthesis, protection from UV, keeps Earth warm, weather and rainfall.

Q4. Describe the hydrosphere and the physico-chemical characteristics of water.

• Global distribution: oceans 97%, ice 2%, groundwater, lakes and rivers less than 1%.
• Physical: temperature, colour, turbidity, light penetration, density.
• Chemical: pH, DO, free CO₂, hardness, alkalinity, chlorides, nitrates and phosphates.
• Show how each affects aquatic animals (e.g. low DO kills fish).

Q5. Explain the formation of soil and the causes of soil erosion.

• Weathering of parent rock: physical (heat, frost, wind), chemical (oxidation, carbonation), biological (lichens, roots, burrowing animals like earthworms).
• Addition of humus; development of horizons.
• Causes of erosion: deforestation, overgrazing, shifting cultivation, mining, heavy rain and wind.
• Effects and control measures.

परीक्षेसाठी टीप

Draw a neat labelled diagram of atmospheric layers with heights. In the water question, always mention DO and pH, as practicals also test them.

थोडक्यात सारांश

An ecosystem is a natural unit in which living organisms interact with each other and with their non-living surroundings. Energy flows and nutrients cycle through it. This topic covers the components of an ecosystem, the main types (forest, grassland, desert and pond), and food chains and food webs.

महत्त्वाचे मुद्दे

• The term ecosystem was coined by A. G. Tansley (1935). Ecosystem is परिसंस्था in Marathi.
• Abiotic components: light, temperature, water, air, soil, minerals (inorganic and organic substances, climatic factors).
• Biotic components: producers (green plants, phytoplankton), consumers (herbivores = primary, carnivores = secondary and tertiary) and decomposers (bacteria, fungi).
• Forest ecosystem: tall trees, shrubs and herbs as producers; deer, insects, birds as primary consumers; fox, snake, tiger as higher consumers. Example: Tadoba forest in Vidarbha.
• Grassland ecosystem: grasses and herbs as producers; grasshoppers, rabbits, cattle as herbivores; frogs, snakes, hawks as carnivores.
• Desert ecosystem: low rainfall, extreme temperature; cacti and thorny shrubs; animals like camel, desert rat, lizards and snakes show water-saving adaptations.
• Pond ecosystem: phytoplankton and rooted plants (Hydrilla, lotus) as producers; zooplankton as primary consumers; small fish, frogs, then big fish and birds as higher consumers; bacteria and fungi in the bottom mud as decomposers.
• A food chain is a straight series of organisms through which food energy passes, each eating the one before it.
• Types of food chains: grazing food chain (starts with green plants), detritus food chain (starts with dead organic matter) and parasitic food chain (from host to parasites).
• A food web is a network of many interconnected food chains. It gives an ecosystem stability: if one food source is lost, consumers can use another.

महत्त्वाच्या संज्ञा

• Producer (autotroph) – makes its own food by photosynthesis.
• Consumer (heterotroph) – depends on other organisms for food.
• Decomposer – breaks down dead matter into simple nutrients.
• Trophic level – the feeding position of an organism in a food chain.
• Detritus – dead plant and animal remains.
• Ecotone – transition zone between two ecosystems.

महत्त्वाची माहिती

• Example grazing chain: grass → grasshopper → frog → snake → hawk.
• Example detritus chain: dead leaves → earthworm → bird.

५ महत्त्वाचे प्रश्न

Q1. Define an ecosystem. Who coined the term?

An ecosystem is a self-sustaining unit of nature made of living organisms and their physical environment, interacting through energy flow and nutrient cycling. The term was given by A. G. Tansley in 1935.

Q2. Distinguish between food chain and food web.

A food chain is a single straight path of energy transfer from producer to top consumer. A food web is a network of many interconnected food chains. A food web is more stable and realistic, because most animals eat more than one kind of food.

Q3. Describe the structure of a pond ecosystem.

• Abiotic: water, dissolved gases, minerals, light, temperature, bottom mud.
• Producers: phytoplankton (algae, diatoms) and macrophytes.
• Consumers: zooplankton (primary), small fish and insects (secondary), large fish and birds (tertiary).
• Decomposers: bacteria and fungi in the mud.
• Zones: littoral, limnetic and profundal.
• Draw a labelled diagram.

Q4. Explain the types of food chains with examples.

• Grazing food chain: plants → herbivores → carnivores (example from grassland or pond).
• Detritus food chain: detritus → detritivores → predators (example from forest floor).
• Parasitic food chain: host → parasite → hyperparasite (e.g. tree → bird → lice → bacteria).
• Importance: energy transfer, balance of populations.

Q5. Compare forest and desert ecosystems.

• Climate and rainfall.
• Producers and their adaptations (broad leaves vs spines and fleshy stems).
• Consumers and their adaptations (camel stores fat; desert rat gets water from food; nocturnal habits).
• Productivity: high in forest, low in desert.
• Decomposers: abundant in forest, few in desert.

परीक्षेसाठी टीप

For any ecosystem question, write abiotic and biotic components under clear sub-headings and finish with a food chain from that ecosystem.

थोडक्यात सारांश

Ecological pyramids are graphs that show the number, biomass or energy of organisms at each trophic level of a food chain. Energy flows in one direction through an ecosystem and much of it is lost at each step. This topic covers the three types of pyramids, their shapes in pond, forest and parasitic food chains, and the single-channel, Y-shaped and universal models of energy flow.

महत्त्वाचे मुद्दे

• Ecological pyramids were first described by Charles Elton (1927), so they are also called Eltonian pyramids.
• The producer level forms the base and the top consumer forms the apex.
• Pyramid of numbers: number of individuals at each level. Upright in grassland and pond; spindle-shaped in a tree-based forest chain; inverted in a parasitic food chain.
• Pyramid of biomass: total dry weight of living matter at each level. Upright on land; inverted in a pond, because the small mass of phytoplankton at any time supports a larger mass of zooplankton and fish (phytoplankton multiply very fast).
• Pyramid of energy: energy at each level per unit area per unit time. It is always upright, because energy is lost at every transfer.
• Energy flow is unidirectional: Sun → producers → herbivores → carnivores. Energy is not recycled; nutrients are.
• Ten percent law (Lindeman, 1942): only about 10% of energy at one trophic level passes on to the next; the rest is lost mainly as heat in respiration.
• Because of this loss, food chains usually have only 4–5 trophic levels.
• Single-channel model: energy flows in one straight line through the trophic levels.
• Y-shaped model (Odum): energy from producers splits into two arms, the grazing food chain and the detritus food chain, which work together.
• Universal model (Odum): applies to any living component; the energy taken in is partly used in respiration, partly stored as growth (production) and partly lost as unassimilated food.

महत्त्वाच्या संज्ञा

• Trophic level – feeding level in a food chain (पोषण पातळी).
• Biomass – total weight of living organisms in an area.
• Gross primary productivity (GPP) – total energy fixed by producers.
• Net primary productivity (NPP) – GPP minus energy used by producers in respiration.
• Standing crop – amount of living matter present at a given time.

महत्त्वाची माहिती

• NPP = GPP − R (R = respiration loss).
• If producers fix 10,000 J, herbivores get about 1,000 J, primary carnivores about 100 J and secondary carnivores about 10 J.

५ महत्त्वाचे प्रश्न

Q1. Why is the pyramid of energy always upright?

At each transfer only about 10% of energy passes to the next level and the rest is lost as heat. So the energy present at every higher level is always less than the level below it.

Q2. Why is the pyramid of biomass inverted in a pond?

Phytoplankton are tiny and short-lived, so their standing biomass at any moment is small. They reproduce very fast and support a larger biomass of zooplankton and fish, so the pyramid becomes inverted.

Q3. Describe the pyramids of number with examples.

• Define pyramid of numbers.
• Upright: grassland (grass → grasshopper → frog → snake).
• Spindle: forest tree supporting many insects and birds.
• Inverted: parasitic chain (one tree → many birds → many more lice).
• Draw all three shapes.

Q4. Explain energy flow in an ecosystem with the Y-shaped model.

• Sun's energy fixed by producers (GPP, NPP).
• Two channels: grazing food chain and detritus food chain.
• Both chains interact; detritus chain handles a large share of energy in forests.
• Lindeman's 10% law; heat loss at each level.
• Draw the Y-shaped diagram.

Q5. Describe the single-channel and universal models of energy flow.

• Single-channel: straight flow from producers to top consumer; respiration loss at each level.
• Universal model: intake (I) → assimilation (A) → production (P) + respiration (R); non-assimilated energy (NU) lost.
• Unidirectional nature of flow and the first and second laws of thermodynamics.

परीक्षेसाठी टीप

Always draw pyramid shapes and energy-flow diagrams; marks are given for labelled figures. Remember the one exception: the energy pyramid is never inverted.

थोडक्यात सारांश

Biodiversity is the variety of all living organisms on Earth, from genes to species to ecosystems. India is one of the world's megadiverse countries, but biodiversity is falling fast because of human activities. This topic covers levels and value of biodiversity, causes of its loss, in-situ and ex-situ conservation, the Wildlife Protection Act 1972, the Biological Diversity Act 2002, the Zoological Survey of India, hotspots, and Tadoba, Nagzira and Kanha.

महत्त्वाचे मुद्दे

• The term biodiversity was popularised by E. O. Wilson (1988). It is जैवविविधता in Marathi.
• Three levels: genetic diversity (variation within a species), species diversity (variety of species in an area) and ecosystem diversity (variety of habitats such as forests, wetlands, deserts).
• Values: food, medicines, timber, fibres, ecological services (pollination, soil fertility, clean water), aesthetic, cultural and ethical value.
• India has about 2.4% of the world's land but about 7–8% of recorded species.
• Causes of loss (HIPPO): Habitat destruction, Invasive species, Pollution, human Population pressure, Over-exploitation (poaching, overfishing). Climate change adds to these.
• In-situ conservation (in the natural habitat): national parks, wildlife sanctuaries, biosphere reserves, tiger reserves, sacred groves.
• Ex-situ conservation (outside the habitat): zoos, botanical gardens, seed banks, gene banks, cryopreservation, captive breeding.
• Biodiversity hotspot: a region with very high endemic species that has lost most of its original vegetation. The concept was given by Norman Myers (1988).
• India's hotspots: Himalaya, Indo-Burma, Western Ghats and Sri Lanka, Sundaland (Nicobar Islands).
• Zoological Survey of India (ZSI): set up in 1916, headquarters Kolkata. It surveys, identifies and documents Indian fauna, keeps national animal collections, and publishes the Red Data Book and fauna of India.

महत्त्वाच्या संज्ञा

• Endemic species – found only in one particular region.
• Endangered species – at high risk of extinction (e.g. tiger, great Indian bustard).
• National park – area strictly protected for wildlife; no human activities like grazing.
• Wildlife sanctuary – protected area where some regulated human activity is allowed.
• Red Data Book – list of threatened species kept by IUCN.

महत्त्वाची माहिती

• Wildlife (Protection) Act, 1972: bans hunting of listed animals; has Schedules giving levels of protection; provides for national parks and sanctuaries; controls trade in wildlife and its products; sets up wildlife advisory boards and the post of Chief Wildlife Warden.
• Biological Diversity Act, 2002: follows the Convention on Biological Diversity (1992); three-tier system – National Biodiversity Authority (Chennai), State Biodiversity Boards, local Biodiversity Management Committees; access and benefit-sharing; People's Biodiversity Registers.

५ महत्त्वाचे प्रश्न

Q1. What is a biodiversity hotspot? Name the hotspots in India.

A hotspot is a region very rich in endemic species that has already lost much of its natural habitat. India has parts of four: Himalaya, Indo-Burma, Western Ghats and Sri Lanka, and Sundaland.

Q2. Write the role of the Zoological Survey of India.

ZSI (1916, Kolkata) surveys and documents India's animals, identifies specimens, maintains national zoological collections, publishes fauna volumes and status reports, and advises the government on animal conservation.

Q3. Explain the causes of reduction of biodiversity.

• Habitat loss and fragmentation (deforestation, dams, roads, urbanisation).
• Over-exploitation: poaching, illegal wildlife trade, overfishing.
• Invasive alien species (e.g. water hyacinth, African catfish).
• Pollution of air, water and soil; pesticides.
• Climate change; forest fires.
• Give one Indian example for each.

Q4. Give the salient features of the Wildlife Protection Act, 1972 and the Biological Diversity Act, 2002.

• Write the points listed under Key facts.
• Mention penalties and the role of each authority.
• Add the importance of these laws for animal conservation.

Q5. Write an introductory account of Tadoba, Nagzira and Kanha.

• Location, area type (national park / sanctuary / tiger reserve).
• Vegetation: dry deciduous teak forest (Tadoba, Nagzira), sal forest and meadows (Kanha).
• Fauna: tiger, leopard, sloth bear, gaur, sambar, chital, wild dog; barasingha in Kanha.
• Conservation role and ecotourism.

परीक्षेसाठी टीप

Questions on local national parks are common in RTMNU papers. Learn at least five animals and the district for each park.

थोडक्यात सारांश

Pollution is the addition of harmful substances or energy to the environment that damages living beings. This topic covers air, water and noise pollution – their sources, effects and control – along with acid rain, the greenhouse effect, ozone depletion, global warming, mercury poisoning, and bioaccumulation and biomagnification.

महत्त्वाचे मुद्दे

• Pollution is प्रदूषण in Marathi. A pollutant is any substance or energy that causes pollution.
• Air pollution sources: vehicles, industries, thermal power plants, burning of crops and garbage, dust from construction. Main pollutants: CO, SO₂, NOₓ, particulate matter (PM2.5, PM10), hydrocarbons.
• Effects of air pollution: asthma, bronchitis, lung cancer, eye irritation; damage to plants and buildings.
• Control: catalytic converters, CNG and electric vehicles, electrostatic precipitators and scrubbers in factories, tall chimneys, planting trees.
• Acid rain: SO₂ and NOₓ dissolve in rain to form sulphuric and nitric acids (pH below 5.6). It harms fish, forests, soil and monuments (marble cancer of the Taj Mahal).
• Greenhouse effect: CO₂, methane, nitrous oxide, CFCs and water vapour trap heat radiated by the Earth. Too much of it causes global warming – melting glaciers, rising sea level, changed rainfall.
• Ozone depletion: CFCs release chlorine that breaks down ozone in the stratosphere; the ozone hole forms over Antarctica. Ozone is measured in Dobson Units. The Montreal Protocol (1987) controls ozone-depleting substances.
• Water pollution sources: sewage, industrial waste, fertilisers and pesticides from farms, oil spills, hot water from power plants.
• Effects: water-borne diseases (cholera, typhoid), fall in dissolved oxygen, eutrophication (algal bloom due to excess nitrates and phosphates), fish death.
• Mercury pollution: methyl mercury in fish caused Minamata disease in Japan (1950s) – nerve damage, numbness, paralysis and birth defects.
• Noise pollution: unwanted loud sound measured in decibels (dB). Sources: traffic, loudspeakers, firecrackers, factories, aircraft. Effects: hearing loss, stress, high blood pressure, sleeplessness.

महत्त्वाच्या संज्ञा

• Bioaccumulation – build-up of a persistent chemical inside one organism over its lifetime.
• Biomagnification – increase in concentration of a persistent chemical at each higher trophic level.
• BOD – biological oxygen demand; high BOD means heavily polluted water.
• Eutrophication – nutrient enrichment of water leading to algal bloom and oxygen loss.
• Smog – smoke plus fog.

महत्त्वाची माहिती

• DDT biomagnification example: water 0.000003 ppm → zooplankton 0.04 ppm → small fish 0.5 ppm → large fish 2 ppm → fish-eating birds 25 ppm. In birds it causes thin eggshells and population decline.
• Safe noise limit in residential areas in India: about 55 dB by day and 45 dB at night (CPCB norms). Above 80–90 dB for long periods damages hearing.
• Indian laws: Water Act 1974, Air Act 1981, Environment (Protection) Act 1986.

५ महत्त्वाचे प्रश्न

Q1. What is biomagnification?

Biomagnification is the increase in the concentration of a non-degradable pollutant such as DDT or mercury at each successive level of a food chain. Top consumers like fish-eating birds get the highest dose.

Q2. What is acid rain? Give its effects.

Rain with pH below 5.6, formed when SO₂ and NOₓ react with water to give sulphuric and nitric acid. It kills fish, damages leaves and soil, and corrodes buildings and monuments.

Q3. Describe the sources, effects and control of air pollution.

• Natural and man-made sources; main pollutants.
• Effects on humans, animals, plants and materials.
• Global effects: greenhouse effect, global warming, ozone depletion.
• Control: devices, cleaner fuels, laws, green belts.

Q4. Write a note on water pollution and the effects of mercury.

• Sources: domestic, industrial, agricultural, thermal.
• Effects: disease, eutrophication, low DO, fish kills.
• Mercury: methylation in water, biomagnification in fish, Minamata disease symptoms.
• Control: sewage treatment plants, effluent treatment, less fertiliser use.

Q5. Explain the greenhouse effect, global warming and ozone depletion.

• Greenhouse gases and how they trap heat; normal role in keeping Earth warm.
• Global warming: causes and effects.
• Ozone layer, CFCs, ozone hole, Dobson Unit, Montreal Protocol.
• Effects of UV on life.

परीक्षेसाठी टीप

Draw the DDT biomagnification chain with numbers; it earns easy marks and works for both bioaccumulation and pollution questions.