Biology Short Notes PDF

Downloaded From www.jeebooks.in Biology Short Notes Contents 1. The Living Wor...

Downloaded From www.jeebooks.in Biology Short Notes Contents 1. The Living World........................................................................................................................................................... 3 2. Bilogical Classification................................................................................................................................................... 5 3. Plant Kingdom............................................................................................................................................................... 9 4. Animal Kingdom.......................................................................................................................................................... 12 5. Morphology of Flowering Plants................................................................................................................................. 17 6. Anatomy of Flowering Plants...................................................................................................................................... 21 7. Structural Organization In Animals............................................................................................................................. 24 8. Cell: Structure And Functions...................................................................................................................................... 27 9. Biomolecules............................................................................................................................................................... 30 10. Cell Cycle and Cell Division........................................................................................................................................ 32 11 Transport In Plants..................................................................................................................................................... 34 12 Mineral Nutrition....................................................................................................................................................... 36 13 Photosynthesis In Higher Plants................................................................................................................................. 39 14 Respiration In Plants.................................................................................................................................................. 41 15 Plant Growth and Development................................................................................................................................ 44 16 Digestion and Absorption........................................................................................................................................... 47 17 Breathing and Exchange f Gaoses.............................................................................................................................. 48 18 Body Fluids and Circulation........................................................................................................................................ 50 19 Excretory Products and Their Elimination.................................................................................................................. 53 20 Locomotion and Movement....................................................................................................................................... 55 21 Neural Control and Coordination............................................................................................................................... 57 22 Chemical Coordination and Integration..................................................................................................................... 59 23 Reproduction In Organisms........................................................................................................................................ 61 24. Sexual Reproduction In Flowering Plants.................................................................................................................. 63 25. Human Reproduction................................................................................................................................................ 65 26. Reproductive Health.................................................................................................................................................. 69 27. Principles of Inheritance and Variation..................................................................................................................... 72 28. Molecular Basis of Inheritance.................................................................................................................................. 77 29. Evolution................................................................................................................................................................... 81 30. Human Health and Disease........................................................................................................................................ 84 31. Strategies For Enhancement In Food Production..................................................................................................... 89 32. Microbes In Human Welfare..................................................................................................................................... 92 1 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes 33. Biotechnology: Principles and Processes................................................................................................................... 95 34. Biotechnology and Its Applications............................................................................................................................ 97 35. Organisms and Populations.................................................................................................................................... 100 36. Ecosystem............................................................................................................................................................... 104 37. Biodiversity and Conservation................................................................................................................................ 108 38. Enviromental Issues................................................................................................................................................ 110 2 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes 1. THE LIVING WORLD Unique Features of Living organism:-  Growth  Reproduction  Metabolism  Consciousness  Life span All processes of life occur in protoplasm and hence Huxley Wrightly called protoplasm as the physical basis of life. It is known as living matter because it shows all properties of life. BIODIVERSITY Currently there are some 1.7 – 1.8 million living organisms known to science. Out of which 1.25 are animals and about 0.5 millions are plants. Use of Systematics 1) Identification 2) Nomenclature 3) Classification Biological nomenclature : For providing scientific name to known organisms. Each name has two components- generic name (genus) and specific epithet (species). This system of nomenclature was provided by Carolus Linnaeus. Taxonomic categories : A taxonomic category is a rank or level in the hierarchical classification of organisms. There are seven obligate categories and some intermediate categories. Taxonomic hierarchy is given below : Kingdom Division Class Order Family Genus Species Taxonomic Aids : Techniques, procedures and stored information that are useful in identification and classification of organisms are called taxonomic aids. Like: 1. Herbarium 2. Museums 3. Zoological park 4. Botanical Garden 5. Key  Key stone species determine the biotic structure of an entire commonly.  Taxonomy is divided into three types by Turil (1938). (1)  (alpha) taxonomy – It deals with collection and identification of organisms on the basis of gross morphology, field and herbarium studies that helps to comile monographs and flora and to identify plants. It is classical taxonomy. 3 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes (2)  (beta) taxonomy – It deals with collection and identification on the basis of morphology and evidences from genetics, cytology, anatomy, physiology, etc. (3)  (omega) taxonomy – It consider all microscopic observations and biochemical evidences and is equivalent to neosystematics (modern taxonomy) and based on phonetic classification.  Father H. Santapau – Father of Indian Taxonomy.  William Roxburgh – Father of Indian Botany and Indian Herbaria.  The term taxonomy was coined and used by French botanist A.P. de Candolle (1813) in his book Theorie Elementaire de La Botanique.  Term systematic was used by Swedish botanist and doctor Linnaeus (father of Taxonomy for his book System Nature (1735).  Famous Books The origin of Life Oparin Principles of Systematic Zoology Emst Mayr Phillosophic Zoologique Lamarck Systema Naturae (1735, 1758) Linnaeus Species Plantarum (1753) Linnaeus Genera Plantarum (1737) Linnaeus Philosophia Botanica Linnaeus  Correlated characters are groups of common features present in different members of a group which are used delimitation of various taxa e.g. common features in different species from a genus. This shows common ancestry.  Revision of Group. It is the grouping of species into distinct taxa of higher category on the basis of their hormology and evolutionary relationship.  Vegetation of an area is described but flora/fauna is listed.  FAA (Formalin aceto-alcohol) is a liquid preservative, most commonly used for preserving anatomy materials.  Botanical survey of India (BSI) was established in 1890. Its head office is at Calcutta. Species with two or more varieties/subspecies is known as polytypic species while the one which has no race/variety/subspecies is called monotypic species. Cohort A group of individuals of the same age within a population. Sympatric species (Sym = Similar). These are genetically unrelated (different) individuals of species having same or overlapping area of geographical distribution. Allopatric species (Allo = different). These are genetically related species having different area of geographical distribution. Lamarck gave dyanamic concept stating that species is mutable and dynamic. Biological concept of species was given by Dobzansky (1937) and Mayr (1942). 4 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes 2. BILOGICAL CLASSIFICATION Biological classification is the scientific procedure of arranging organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing the group in a hierarchy of categories. Kingdom System of Classification Two Kingdom Three Kingdom Five Kingdom Plantae Plantae Monera Animalia Protista Protista Animalia Fungi Plantae Animalia  Eichler and Engler and Prantl phylogenetic systems are transitional (partly) phylogenetic.  Phylogeny is developmental history of entire race. Haeckel proposed concept of phylogeny.  Term monera was used by Dogherty and Allen. Phyletic Classification. It is a type of phylogenetic classification based on the relationship to a particular line of descent. There are two components of phyletic relationships. (i) Patristic (a term used for similarities between two plants due to a known common ancestry) (ii) Cledistic (L Cledos = branch, term used for closeness of relationship in terms of phyletic lines). Cladistlcs (phylogenetic systematics) is a method of classification (given by wiilii henning) (also called hennigian classification)  Green Data Book (GDB). It gives information about rare plants growing in botanical gardens/protected areas.  Blue Book. United Nations environment Programme (UNEP) has compiled endangered species of the world under the title Blue Book.  Traffic. Trade record analysis of flora and fauna in commerce  UNESCO – United Nations Educational Scientific and Cultural Organisation.  IUCNNR (IUCN) – International Union for Conservation of Nature and Natural Resources or IUCN.  GEF – Global Environmental Facility.  BHNS – Bombay Natural History Society, Mumbai (its logo is Hombill)  WWF-N – World wide Fund for Nature (Old name was WWF – World wild life fund). Since 1986, it is WWF-N. Its logo is giant panda Ailusopoda melanoleuca..  IBWL – Indian Board for Wild life (1952)  WPSI – Wild life Preservation Society of India. Dehradun.  UNEP – United Nations Environments Programme.  NBPGR – National Bureau of Plant Genetic Resources, New Delhi.  NBAGR – National Bureau of Animal Genetic Resources, Karnal.  Mixotrophy. This nutrition is found in eugienoids which show photosynthetic mode of nutrition in light and become hotozoic in the absence of light.  Albizzia falcate is world s fastest growing tree. 5 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Lornatia tasmanica is longest living plant (43000 years old).  Butea monosperma is called flame of the forest. 1. Monera – The kingdom includes all prokaryotes – mycoplasma, bacteria, actinomycetes, and cyanobacteria. (a) Unicellular, prokaryotes and containing the most primitive of living forms. (b) The cells are microscopic and cell wall is generally present. (c) Genetic materials are not organized into nucleus and contain naked DNA. (d) Membrane bounded organelles are absent. (e) Reproduction is asexual except gene recombination. (f) Flagella may be present and are of single stranded. Example – Blue-green algae, Bacteria etc. Bacteria: Shapes: Coccus: spherical shaped Spirillum: spiral or coiled shaped Bacillus: rod shaped Vibrio: comma shaped Archaeobacteria – They are group of most primitive prokaryotes which live under most hostile conditions like extreme-salty area (halophiles), hot springs (thermoacidiophiles) and marshy area (methanogens). The call wall structure shows absence of peptidoglycan. Methanogens are responsible for production of biogas (methane). Eubacteria – They are called as true bacteria contain rigid cell wall, if motile contain flagellum. Cyanobacteria or blue-green algae are gram positive photosynthetic bacteria. They contain chlorophyll a and carotenoids. They may be unicellular, colonial or filamentous, fresh water, marine or terrestrial. Some of them have specialized heterocyst cells to perform nitrogen fixation (Nostoc and Anabaena). Chemosynthetic bacteria oxidize inorganic substances like nitriate, nitrite, ammonia etc. to produce energy and help in recycling of nitrogen, phosphorous, sulphur etc. Heterotrophic bacteria are helpful in production of curd, antibiotic and fixing nitrogen in leguminous plants. Mycoplasma – They are the simplest free living prokaryotes. They are also known as PPLO (Pleuropneumonia like organism). They lack cell wall and can survive without oxygen. 2. Protista – Kingdom Protista includes Chrysophytes, Dinoflagellates, Eugleoids, Slime mould and Protozoans. (a) It includes all unicellular and coloniel eukaryotes. (b) Most of them are aquatic forming plankton. (c) Mode of nutrition may be photosynthetic, saprobic, parasitic or holozoic. (d) Flagella if present are 11 stranded with 9 + 2 arrangement of microtubules composed of tubulin. (e) Genetic material consists of 2 or more DNA molecules. 6 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Chrysophytes  They includes diatoms and golden algae (desmids) found in fresh water as well as marine water.  In diatoms cell wall forms two thin overlapping cells which fit together as in soap box.  The siliceous indestructible cell wall pile up at the bottom of water reservoirs and form big heaps called diatomaceous earth. Dinoflagellates  They are basically unicellular motile, biflagellate and photosynthetic protists.  Predominate colour is golden brown but yellow, green, red and even blue.  Some Dinoflagellates like Gymnodinium and Gonyaulax grow in large number in the sea and make the water look red and cause the so called red tide. Eugleoids  They are Euglena like unicellular flagellates which possess pellicle instead of cell wall which make their body flexible.  They have two flagella, one short and other long.  They are photosynthetic in presence of sunlight and act as predators in absence of sunlight.  Example – Euglena, Peranema. Slime Moulds  They are saprophytic protists and feeds on decaying twinges and leaves.  Under favorable condition, they form an aggregation called plasmodium which produce fruiting bodies bearing spores.  The cell wall of spores bears cellulose.  Example – Physarum, Fuligo. Protozoans  All protozoans are heterotrophs and live as predators of parasites. Classified as:  Amoeboids: Amoeba, Entamoeba  Flagellated protozoans: Trypanosoma  Ciliated protozoans: Paramoecium  Sporozoans: Plasmodium 3. Fungi –  They are achlorophyllous, heterotrophic, spore forming, non-vesicular eukaryotic organisms.  Cell wall is made up of chitin or fungal cellulose. 7 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Reserved food is glycogen.  Mode of nutrition is saprophytic, parasitic or symbiotic.  Reproduction may be vegetative (Fragmentation, fission or budding), asexual (conidia, sporangiospores or zoospores) or sexual reproduction by oospores, ascospore and basidiospores.  Sexual cycles involves the following steps – a) Plasmogamy, fusion of male and female gametes. b) Karyogamy, fusion of two nuclei. c) Meiosis in zygote to produce haploid spores. Phycomycetes-  They are found in aquatic habitat and on decaying wood in moist and damp places.  The mycelium is aseptate and coenocytic.  Asexual reproduction by zoospores (motile) or aplanospores (non-motile).  Example-Mucus, Rhizopus, Albugo etc. (b) Ascomycetes (The sac fungi)  They are saprophytic, decomposers, parasitic or coprophilous (growing on dung).  Mycelium and branched and septate and asexual spores are conidia.  Sexual spores are called ascospores produced inside the fruiting body called ascocarps. Example- Neurospora, Asperigillus, Claviceps etc. (c) Basidiomycetes (The club fungi)  The mycelium is branched and septate.  Vegetative reproduction is by fragmentation. Asexual spores are not found. Sexual reproduction is by two vegetative or somatic cells forming basidium.  Basidiospores are produced in basidium by developing a fruiting body called basidiocarps.  Example – Agaricus, Ustilage, Puccinia (d) Deuteromycetes (The fungi imperfect)  Only vegetative and asexual phase is known.  Mycelium is septate and branched. Some members are saprophytes or parasites.  Example – Alternaria, Trichoderma, Colletotrichu 4. Plantae  Kingdom plantae includes Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms. 5. Animalia Heterotrophic, eukaryotic organisms that are multicellular and cell wall is absent in the cell. Virus, Viroids and Lichens 8 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Five kingdom system of classification does not includes Virus, Viroids and Lichens  Viruses are non-cellular organisms having inert crystalline structure outside the living.  In addition to proteins, viruses also contain genetic material that could be DNA or RNA. In general, virus that infect plants have single stranded RNA and virus that infect animals have double stranded DNA.  Bacteria feeding virus are called bacteriophage.  Viroids are discovered by T.O. Diener as new infectious agent smaller than virus causing potato spindle tuber disease. They are free RNA without protein coat.  Lichens are symbiotic association between algae and fungi. The algal part is called Phycobiont and fungal parts are called Mycobiont.  The term protozoa was given by Goldfuess.  Protozoans were observed for the first time by leeuwanhoek.  Unicellular nature of the protozoans was recognized by von selbold.  Dobel described protozoans as acellular animals.  Food vacuoles in protozoans are also known as gastrioias. The term gastriole was given by volkovsky.  Contents of food vacuoles in Amoeba are first acidic in nature and later alkaline.  Hyman (1917) first proposed sol – gel theory.  Pinocytosis in Amoeba was first studied by Mast and Doyle (1934).  Giant amoeba is Pelomyxa or Choas chaos.  Protarospongia. A colonial protozoan, a connecting link between protozoa/Protista and Porifera/Meta-zoa.  Hydramoeba. Ectoparasitic protozoan which feeds on epidermal cells of Hydra..  If a Amoeba is placed in distilled water its contractile vacuole works faster.  If an Amoeba is placed in salt water, its contractile vacuole disappears.  Study of viruses is called virology. Father of virology is Stanley STNV is parasite on another virus.  Pseudo virion. A pseudo virion contains host cell DNA instead of the viral genome.  Small pox eradication programs was started by WHO in 1967.  Viruses can be cultured on living cells by (i) host tissue culture method. (ii) Chick embryo method. Chorioallantoic membrane is widely used tissue to culture animal viruses.  Hepatitis A virus (HAV) is most stable virus infecting humans. It can withstand heating at 56oC for 30 minutes and treatment with diethyl ether.  Most mutable virus is HIV. Second most mutable is influenza virus. TMV is most resistance virus. 3. PLANT KINGDOM Plant Kingdom is subdivided as follows: (A) Cryptogamae (Plants without seeds) (B) Phanerogamae (Plants with seeds) a. Thallophyta a. Gymnosperm b. Bryophyta b. Angiosperm c. Pteridophyta 9 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Thallophyta – Comprises the simplest plants which possess undifferentiated or thallus like forms, reproductive organs single called gametangia. It includes only algae. Characteristic of algae  Plant body is thallus, which may be unicellular, colonial, filamentous or parenchymatous.  Vascular tissues and mechanical tissue are absent.  Reproduction is vegetative by fragmentation, asexual by spore formation (zoospores) and sexual reproduction by fusion of two gametes which may be Isogamous (Spirogyra) Anisogamous (Chlamydomonous) or Oogamous (Volvox).  Life cycle is various-haplontic or diplohaplontic.  Algae is subdivided as: Chlorophyceae, Phaecophyceae, Rhodophyceae. Green Algae Brown Algae Red Algae Mostly fresh water and sub aerial Mostly marine Mostly marine Chlorophyll a and b type Chlorophyll a and c type Chlorophyll a and b type Reserve food is starch Reserve food is laminarin Reserve food is floridean starch Cell wall is of cellulose Cell wall contains cellulose and Cell wall contains cellulose and poly-sulphate algin esters Zoospores present. Zoospores present. Zoospores absent Chlamydomonas, Ulothrix, Focus, Sorgassum, ectocarpus Polysiphonia, Gelidium, Porphyra etc Spirogyra Economic importance – (i) A number of brown algae (Laminaria, Sargassum) are used as food in some countries. (ii) Fungus and Laminaria are rich source of iodine. (iii) Laminaria and Ascophyllum have antibiotic properties. (iv) Alginic acid is obtained from fungus and liverworts that grow in moist shady region. Bryophytes – They are non-vascular mosses and liverworts that grow in moist shady region. They are called amphibians of plants kingdom because these plants live on soil but dependent on water for sexual reproduction. Characteristic features –  Roots are absent but contain rhizoids  Vegetative reproduction is by fragmentation, tubers, gemmae, buds etc. Sex organs are multicellular and jacketed. Antheridium and archegonium produce male and female gametes called antherozoids and egg or oospore.  Sporophyte is parasite on gametophyte.  Bryophytes divided as: Hepaticopsida(Liverworts), Bryopsida (Mosses) Liverworts 10 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  The thallus is dorsiventral flattened, dichotomously branched with or without leaf-like appendage.  Unicellular rhizoids, multicellular scales and completely parasitic sporophyte or sporangium.  Asexual reproduction takes place by fragmentation thallus or formation of specialized structure called gammae. Gemmae are given, multicellular, asexual buds, which develops in small receptacles called gemmae cups. The gemmae becomes detached from the parent body and germinate to form new individuals.  During sexual reproduction male and female sex organs are produced on same thallus or different.  The sporophyte is differentiated into foot, seta and capsule. Mosses –  The gametophyte of mosses consists of two stages the first stage is protonema stage. The second stage is the leafy stage.  Vegatative reproduction by the fragmentation and budding in secondary protonema. A sex organ develops on leafy shoots.  Common examples are funaria, Polytrichum, Sphagnum etc. Pteridophytes –  They are seedless vascular plants that have sporophytic plant body and inconspicuous gametophyte.  Vascular tissue are present but vessels are absent from xylem and companion cells and sieve tube are absent.  In some plants (Selaginella) compact structure called strobili or cone is formed.  Sporangia produce spores by meiosis in spore mother cells. Spores germinate to produce multicellular thalloid, prothallus.  Gametophyte bears male and female sex organ called antheridia and archegonia. Water is required for fertilization of male and female gametes.  Most of Pteridophytes produce spores are of similar kind (homosporous) but in Selginella and Salvinia, spores are of two kinds (heterosporous) larger called megaspore that produce female gematophyte and smaller microspore that produce male gametes.  Pteridophtyes Classes: Psilopsida ( psilotum), Lycopsida (Lycopodium, Selaginella), Sphenopsida (Equisetum), Filicopsida (Pteris, Adiantum). Gymnosperms  Gymnosperms are those plants in which the ovules are not enclosed inside the ovary wall and remain exposed before and after fertilization.  Stem may be unbranched (Cycas) or branched (Pinus). Root is tap. Leaves may be simple or compound.  They are heterosporous, produce haploid microspore and megaspore in male and female Strobili respectively.  Example-Pines, Cycas, Cedrus, Ginkgo etc. Angiosperms  Pollen grain and ovules are developed in specialized structure. Flower seeds enclosed inside the fruits.  Size varies from almost microscopic Wolfia (0.1 cm) to tall tree Eucalyptus (more than 100m).  Angiosperms divided into two classes: Dicotyledons and Monocotyleons 11 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Monocotyledons Dicotyledons a. Single cotyledons. a. Two cotyledons. b. Parallel venation. b. Reticulate venation. c. Fibrous root system. c. Tap root system. d. Closed vascular bundle. d. Open vascular bundle. e. More number of vascular bundles. e. Less number of vascular bundles. f. Banana, wheat, rice. f. Gram, mango, apple.  Double fertilization- Each pollen grain produce two male gametes. One gamete fuses with egg to form embryo, Syngamy and other gametes fuse with two polar nuclei to form endosperm, triple fission. Since fertilization takes place twice so, it is called double fertilization. Alternation of generation Different plant groups complete their life cycles in different patterns. Angiosperms complete their life cycle in two phases- a diploid sporophytes and haploid gametophyte. The two follows each other. This phenomenon is called alternation of generation. (a) Haplontic- Saprophytic generation is represented by only the one-celled zygote. Meiosis in zygote results into haploid spores to form gametophytes, which is the dominant vegetative phase. Example- Volvox, Spirogyra etc. (b) Diplontic- Diploid sporophytes is dominant, independent, photosynthetic plants. The gametophyte is represented by single to few celled. All seed bearing plants fall under this category. (c) Haplo-diplontic- Both phases are multicellular and intermediate condition is present. It is present in Bryophytes and Pteridophytes. 4. ANIMAL KINGDOM  Animals are classified on the basis of arrangement of cells, body symmetry, nature of coelom, pattern of digestive, circulatory and reproductive system.  Open circulatory system- blood is pumped out of heart and cells and tissue are directly bathed in it.  Closed circulatory system- blood is circulated through arteries, veins and capillaries.  The animals in which cells are arranged in two embryonic layer, external ectoderm and internal endoderm are called diploblastic. Eg. Porifera and Cnidaria. 12 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  The animals in which developing embryo has a third germinal layer, mesoderm besides ectoderm and endoderm are called triploblastic. Eg. Platyhelminthes, Chordates. The body cavity which is lined by mesoderm is called coelom. Animals possessing coelom are called coelomate (Annelida, Chordates, Mollusca). In some animals cavity is not lined by mesoderm but scattered as pouches in between ectoderm and endoderm, are called pseudo-coelomates (Aschelminthes). The animals in which body cavity is absent are called acoelomate (Platyhelminthes). In some animals, body is externally and internally divided into segments with serial repetition as in earthworm, called metameric segmentation. CLASSIFICATION OF ANIMALS 1. Phylum Porifera-  Members of this phylum are commonly known as sponges. Mostly marine, asymmetrical and have cellular level of organization.  They have water transport or canal system. Water enters through minute pores, Ostia into central cavity Spongocoel, from where it goes out through Osculum.  Nutrition, respiration and excretion is performed by pathway of water transport system.  Skeleton made up of spicules or spongin fibres. 13 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Egg and sperms are produced by same organism (hermaphrodite). Asexual reproduction by fragmentation and sexual reproduction by gametes formation.  Example- Sycon, Spongilla. 2. Phylum Cnidaria ( Coelenterate)-  They are aquatic, mostly marine, sessile, free swimming, radially symmetrical animals.  They exhibit tissue level of organization, diploblastic, coelomate with single opening.  They show two types of body called polyp and medusa.  Polyp is sessile, fixed, and cylindrical, without gonads such as Hydra, Adamsia and Medusa is free swimming, umbrella like having four gonads like Aurelia and Jelly fish.  Some cnidarians exhibits both forms (Obelia), polyp produce medusa asexually and medusa produce polyp sexually. 3. Phylum Ctenophora-  Commonly known as the Comb Jellies or Sea Walnuts.  Exclusively marine, diploblastic, radially symmetrical, with tissue level of organization.  Body bears eight ciliated comb plates which help in locomotion.  Bioluminescence (to emit light) is present in Ctenophores.  Hermaphrodite, fertilization external, development indirect,  Example- Ctenoplana, Pleurobranchia. 4. Phylum Platyhelminthes (The Flat worms)  Dorso-ventrally flattened body, bilaterally symmetrical, triploblastic, acoelomate with organs levels of organization.  Hooks and sucker are present in parasitic forms. Flame cells help in osmoregulation and excretion.  Fertilization is internal, development is indirect, hermaphrodite.  Example- Taenia, Planaria, Fasciola. 5. Phylum Aschelminthes ( The Round Worm)  They may be free-living, aquatic, terrestrial or parasitic in plants or animals.  Bilaterally symmetrical, triploblastic, pseudo coelomate.  Alimentary canal is complete with well-developed muscular pharynx.  Dioecious, females are longer than male.  Example- Ascaris (round worm), Wucheriria (filarial worm), Ancyclostoma. 6. Phylum Annelida  Aquatic or terrestrial, bilaterally symmetrical, segmented with organ system level of organization.  Aquatic Annelids like Nereis possesses lateral appendages parapodia, for swimming. Nephridia help in osmoregulation and excretion. Neural system consists of paired ganglia. 14 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Dioecious (Nereis) or monocious (earthworm, leech)  Example- Pheretima (earthworm), Hirunidaria (Blood sucking leech). 7. Phylum Arthropoda  Largest phylum of animals which includes insects. Organ system of organization, triploblastic, coelomate, bilaterally symmetrical with chitinous exoskeleton.  Body consists of head, thorax and abdomen, jointed appendages (jointed feet). Respiratory organs are gills, book lungs or tracheal system with open circulatory system.  Excretion through malpighian tubules, sense organs antenna or eyes. Fertilization internal, mostly oviparous.  Example- Economically important- Apis (honey bee), Bombyx (silk worm). Vectors- Anopheles, Ades, Culex (mosquito). Living fossils- Limulus (king crab) 8. Phylum Mollusca  Terrestrial or aquatic, organ level of organization, bilaterally symmetrical, triploblastic and coelomate.  Body divided into head, muscular foot and visceral hump. Unregimented and covered with calcareous shell.  Feather like gills are present between hump and mantle.  Mouth contains file like rasping organ for feeding called radula.  Example- Pila, Octopus. 9. Phylum Echinodermata (The Spiny Skinned Animals)  Endoskeleton of calcareous ossicles, marine with organ system of organization.  Triploblastic, coelomate, presence of water vascular system help in locomotion, capture of food and respiration.  Sexes are separate, fertilization is external and development is indirect.  Example- Asterias (Star fish), Cucumaria (Sea cucumber), Antedon (Sea lily). 10.Phylum Hemichordata  Worm-like marine animals with organ system of organization, bilaterally symmetrical, triploblastic and coelomate animals.  Body is cylindrical, composed of anterior proboscis, a collar and a long trunk.  Open circulatory system, respiration by gills, excretory organ is proboscis glands.  Sex separate, fertilization is external, indirect development.  Example- Balanoglossus, Saccoglossus. 11.Phylum Chordates 15 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Presence of notochord, a dorsal hollow nerve chord and paired pharyngeal gill slits.  Bilaterally symmetrical, triploblastic, coelomate with organs system levels of organization.  Closed circulatory system, ventral heart, post-anal tail is present.  Subphylums are Urochordata, Cephalochordata, Vertebrata.  In Urochordata, notochord is present only in larval tail.  In Cephalochordate it extends from head to tail and persists throughout the life.  Vertebrata possesses notochord in embryonic period which is replaced by vertebral column in the adults.  Sub-phylum Vertebrata is further divided into two division Agnatha ( lacks jaw) and Gnathostomata ( bears jaw).  Gnathostomata is further divided into two super class- Pisces ( bears fins) and Tetrapoda (bears limbs). Class Cyclostomata (Circular mouthed fishes)-  They are ectoparasites on some fishes. Having sucking and circular mouth without jaws.  Body devoid of scales, gill slits for respiration, cranium and vertebral column is cartilaginous.  Circulation is closed type. They are marine but migrate to fresh water for spawning and die after few days. Larva return to seas after metamorphosis.  Example- Petromyzon (Lamprey), Maxine (Hag fish). Class Chondrichithyes ( The Cartilaginous Fish)  They are marine, streamlined body, bears cartilaginous endoskeleton, cold blooded, tough skin with minute placoid scales.  Gill slits are separate with operculum, powerful jaw and predator.  Air bladder is absent, to avoid sinking swims constantly. Heart is two chambered, cold blooded (Poikilothermus).  Sexes separate, in males pelvic fins bears claspers. Internal fertilization, many are viviparous.  Electric organ is present in Torpedo and Poison sting in Trygon Example- Scoliodon (Dog fish), Carcharodron (great white shark). Class Ostechthyes (The body fish)  Marine and fresh water both with bony endoskeleton. Streamlined body with four pair of gills covered by operculum.  Skin is covered with scales, air bladder is present, and heart is two chambered, cold blooded.  Sexes are separate, fertilization is external, oviparous and development direct. Example: Marine- Hippocampus (Sea horse), Exocoetus (Flying fish). Fresh water- Labeo (Rohu), Catla , Clarias (Magur). Class Tetrapoda: Subdivided as: Amphibia, Reptilia, Aves, Mammals. Amphibia Reptilia Aves Mammals 16 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Lives in aquatic as well Mostly terrestrial Presence of feathers for Mostly terrestrial, a few can fly as terrestrial habitat. animals. flying. and live in water. Two pairs of limbs. Limbs two pair if Forelimb is modified into Two pair of limbs. present. wings. Moist skin without Dry and cornified skin Skin is dry without glands. Mammary gland is present to scales. having scale or scute. Long bones are hollow with produce milk. Skin possesses hairs. air cavities. Respiration by gills, Respiration by lungs. Respiration by lungs. Respiration by lungs. lungs or skin. Heart three Heart three Heart is four chambered, Heart is four chambered. chambered, cold chambered, warm blooded. blooded. Crocodile 4- chambered. Oviparous. Oviparous. Oviparous. Viviparous or Oviparous. Rana (frog), Chamelion, Columba, Pavo, Ostrich. Platypus(oviparous), Camel, Dog, Salamander. Crocodilus, Naja Blue whale. 5. MORPHOLOGY OF FLOWERING PLANTS The Root  In Dicotyledons, elongation of radicle forms the primary roots which bears lateral roots of several orders called secondary roots, tertiary roots etc.  Primary roots along with lateral roots forms the Tap root system. Mustard, Gram etc.  In monocotyledons, primary root is replaced by large number of roots at its base of stem to constitute the Fibrous root system. Wheat, rice etc.  The roots that arise from other parts of plant beside radicle are called adventitious roots. Example- Grass, Banyan tree, Maize etc. Regions of Roots- 17 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Modification of roots- Roots are modified for storage, nitrogen fixation, aeration and support.  Tap root of carrot (conical tap root), radish (fusiform tap root), turnip (napiform tap root) and adventitious root of sweet potato get swollen to store food.  Prop root of Banyan and Stilt root of maize and sugarcane have supporting root coming out from lower node of stems.  In Rhizophora, Pneumatophores help to get oxygen for respiration as it grows in swampy areas. The Stem  It develops from Plumule of the embryo.  Stem bears nodes and internodes. The region of stem where leaves are born called nodes and portion between two nodes are called internodes. Modification of stems-  Underground stem modifications act as organ of perennation in unfavorable conditions. Types are as follows: Sucker: Mint, Chrysanthemum Rhizome: Ginger Corm: Colocasia Tuber: Potato Bulb: Onions, Garlic  Stem tendril help plants to climb as in cucumber, pumpkins, and grapes.  Axillary buds of stem may modify into woody, straight and pointed thorns as in Citrus and Bougainvillea. The Leaf –  Leaf is a green, dissimilar exogenous lateral flattened outgrowth which is borne on the node of a stem or its branches.  Leaves originate from shoot apical meristem and are arranged in an acropetal order.  A typical leaf consists of three parts- Leaf base, Petiole, Lamina.  Leaf is attached with stem by Leaf Base which may bear two small leaf like structure called stipule. 18 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Middle prominent vein is called mid vein.  The arrangement of vein and veinlets in the lamina is called venation. Reticulate venation Parallel venation a. Veinlets form a near network. a. A network is absent. b. Veins are irregularly distributed. b. Veins are parallel to one another. c. It is present in all Dicotyledons like Gram, Pea, c. It is present in Monocotyledons like Grass, Beans, and Mango etc. Banana, Rice etc. Types of Leaves (a) Simple Leaves (b) Compound leaves: Pinnately compound leaves and Palmately compound leaves  The pattern of arrangement of leaves on the stem or branch is called Phyllotaxy.  In alternate type of phyllotaxy single leaf arise at each node as in China rose.  In opposite type of phyllotaxy a pair of leaves arise from each node opposite to each other as in Guava.  If more than two leaves arise at a node and form a whorl is called whorled type of phyllotaxy as in Alastonia. Inflorescence The arrangement of flowers on the floral axis is termed as inflorescence. Two main types of inflorescence are racemose and cymose. The flower  A typical flower has four whorls arranged on a swollen end of stalk or pedicel called thalamus. They are Calyx, Corolla, Androecium and Gynoecium.  When flower can be divided into two equal radial halves in any radii passing through center the symmetry of flower is called actinomorphic  When flower can be divided into two similar parts only in one vertical plane it is zygomorphic  Floral appendages are in multiple of 3,4 or 5 they are called trimerous, tetramerous and pentamerous respectively. Flower with reduced small leaf at the base of pedicel are called bracteates and without it ebracteate.  Based on the position of ovary with respect to other floral part on thalamus flowers are of following types: (a). Hypogynous flower (b). Perigynous flowers (c). Epigynous flowers Calyx is the outermost whorls of the flower ; its members are called sepals. It may be gamosepalous (sepals united) or polysepalous (sepals free). Corolla consists of petals, they may be gamopetalous or polypetalous.  The mode of arrangement of sepals or petals in floral bud with respect to the other members of same whorl is called aestivation. 19 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Types are: Valvate, Twisted, Imbricate, and Vaxillary aestivation. The Androecium  Androecium represent the male reproductive parts of flower, consists of stamens. Each stamen consists of filament and anther. Sterile stamen is called Stemenode.  When stamens are attached with petals it is called epipetalous (Brinjal).  Stamen may be free (polyandrous) or may be united in one bundle (monoadelphous), two bundles (diadelphous), more than two (polyadelphous). The Gynoecium  Female reproductive part of flower consists of one or more carpels. Each carpel is made up of stigma style and ovary.  When more than one carpel is present, it may be free (apocarpous) as in lotus and rose or fused together (syncarpous) as in mustard and tomato. Placentation  The arrangement of ovules within the ovary is called placentation.  Types are: a) Marginal (pea) b) Axle (china rose) c) Parietal (mustard) d) Free central (dianthes) e) Basal (sunflower) The fruit  Mature and ripened ovary developed after fertilization is fruit. If a fruit is formed without fertilization of ovary it is called parthenocarpic fruit.  Fruit consists of seeds and pericarp. Thick and fleshy pericarp is three layered called epicarp, mesocarp and endocarp. The Seed  Dicotyledonous Seed is made up of a seed coat and an embryo. Embryo is made up of embryonal axis, radicle and cotyledons.  Seed coat has two layers outer testa and inner tegmen. Hilum is scar through which seed is attached to the ovary. Small pore above the hilum is called micropyle.  In monocotyledonous seed, outer covering of endosperm separate the embryo by a protienous layer called aleurone layer.  Single cotyledon is called as scutellum having a short axis bearing Plumule and radicle.  Plumule and radicle are closed inside sheaths called as coleoptile and coleorhizae respectively. 20 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes 6. ANATOMY OF FLOWERING PLANTS The tissue  A group of cells having a common origin and usually performing common function are called tissues.  Plant tissues divided as:  Meristematic Tissue: a). Apical Meristem b). Intercalary Meristem c). Lateral Meristem  Permanent Tissue: 1. Simple Permanent Tissue: a). Parenchyma b). Collenchyma c). Sclerenchyma 2. Complex Permanent Tissue: a). Xylem b). Phloem  Parenchyma is a simple permanent living tissue  Collenchyma Consists of cells which are much thickened at corner due to cellulose, hemicelluloses and pectin. They provide mechanical support to the growing parts of the plant like young stem.  Sclerenchymas are supportive tissue having highly thick walled cells with little or no protoplasm due to deposition of cellulose or lignin. They are of two types fibres and sclereids. Complex Tissues – Xylem and phloem constitute the complex tissues in plants and work together as a unit. Xylem Phloem (a). It conducts water or sap. (a). Phloem conducts organic food. (b) Xylem is made up of vessels, tracheid, xylem (b). Phloem is made up of sieve tube, companion cells, phloem fibre and xylem parenchyma. parenchyma and phloem fibres. 21 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Primary xylem is of two types – Protoxylem and mataxylem.  In gymnosperms, albuminous cells and sieve cells, they lack sieve tube and companion cells. Epidermal Tissue System  It forms the outermost covering of whole plant body, which consists of epidermal cells, stomata, epidermal appendages (trichomes and hairs).  In dicots, stomata are bean-shaped having two guard cells closing the stomatal pore. In monocots, stoma is dumbbell-shaped. Guard cells contain chloroplasts that help in opening and closing of stomata.  Trichomes are present on stems, which are multicellular, branched or unbranched preventing water loss due to transpiration. The ground Tissue System  All the tissue between epidermis and vascular bundle forms the ground tissues.  Leaves the mesophyll, chloroplast containing cell forms the ground tissues. The Vascular Tissue System  The vascular system consists of complex tissue, xylem and phloem that together form vascular bundles.  Open vascular bundle (cambium between xylem and phloem) found in dicot stem.  Closed vascular bundle (cambium absent between xylem and phloem) found in moncot stem.  When xylem and phloem within a vascular bundle are arranged in alternate manner on different radii, the arrangement are called radial as in roots.  When xylem and phloem are situated at the same radius of vascular bundle, it is called conjoint as in stem and leaves. Dicotyledonous Root  The outermost layer of dicot root is epidermis containing unicellular root hairs.  The innermost layer of cortex is called endodermis having waxy material suberin as casparian strips.  Pericycle is present below endodermis.  Two to four xylem and phloem patches are present. Monocotyledonous Roots  Anatomically monocots roots epidermis cortex, endodermis, pith are similar to dicots except having more than 6 vascular bundles with larger pith. 22 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Dicotyledonous Stem  Epidermis is the outermost layer of dicot stems having thin layer of cuticle, may contain trichomes and hairs.  Cortex is divided into three sub layers- outer hypodermis (collenchymatous), middle cortical layer (parenchymatous) and inner endodermis, which is rich in starch grains so, also known as starch sheath.  Vascular bundles are conjoint, open, endarch with protoxylem. Pith is the parenchymatous with intercellular spaces. Monocotyledonous Stem  They have sclerenchymatous hypodermis, large number of scattered vascular bundles surrounded by sclerenchymatous bundle sheath. Vascular bundles closed and conjoint. Phloem parenchyma is absent. Dicotyledonous Leaf (Dorsi-ventral)  Epidermis covers both upper (adaxial) and lower (abaxial) surface. Abaxial surface have more stomata.  Mesophyll bears chlorophyll to carryout photosynthesis, are made up of parenchyma. Spongy parenchyma are spherical and loosely arranged but palisade parenchyma are elongated.  Vascular system includes vascular bundles, which are seen as veins and midribs. Monocotyledonous leaf (Isobilateral) 23 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Stomata are present on both surfaces of epidermis and mesophyll cells are not differentiated as spongy and palisade cells.  In grasses, some adaxial epidermal cell with veins modify into large, empty, colourless cells called bulliform cells. Secondary Growth  It is the growth in girth (thickness) due to the formation of secondary tissues by lateral meristems (vesicular cambium and cork cambium).  In dicot stem, cambium present between xylem and phloem is called intrafascicular cambium. The cells of medullary rays become meristematic to form interfascicular cambium, which together form the complete ring of cambium.  Cork cambium or phellogen is formed in the outer cortex of stem.  Cork is impervious to water due to deposition of suberin in cell wall. Phellogen, phellem and phelloderm are collectively called periderm.  Secondary growth also occurs in stem and root of Gymnosperms but not in monocotyledons. 7. STRUCTURAL ORGANIZATION IN ANIMALS Epithelial Tissue This tissue provides covering or lining for some part of the body. Types of tissues are:  Simple epithelium  The compound epithelium  The squamous epithelium  Cuboidal epithelium  Columnar epitheliums  Columnar ciliated epithelium  Columnar and cuboidal epithelium specialized for secretion are known as glandular epithelium, which may be unicellular as in goblet cells of alimentary canal or multicellular as in salivary gland. 24 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Connective Tissues They are most abundant and widely distributed tissues which link and support the other tissues. All connective tissue except blood, cell secretes fibres of structural protein called collagen or elastin to provide elasticity and flexibility.  Loose Connective Tissues contain cells and fibres loosely arranged in semi-fluid ground substance. It includes areolar tissue and adipose tissue. Areolar Connective Tissue Adipose Connective Tissue It contains fibroblast, macrophages and mast cells Fibroblast, macrophages and mast cells are absent.  Dense connective Tissue contains fibres and fibroblast compactly packed. The orientation of fibres may be regular or irregular pattern. Cartilage Bone They are soft skeletal tissue Bones are hard skeletal tissue Chondriocyctes are enclosed in small cavities with matrix They are rich in Calcium salt and collagen fibres They are present in tips of nose, outer ear, between They form the skeletal framework of vertebrates like vertebral bones limbs, legs etc.  Blood is fluid connective tissue containing plasma, red blood cells, white blood cells and platelets. Muscle Tissue Each muscle is made up of long cylindrical fibres arranged parallel to each other. Fibres are composed of fine fibrils called myofibrils. Muscle fibres contract and relax in response to stimulation. Skeletal Smooth Cardiac They are also known as striated, They are known as unstriated or They are known as heart muscles and voluntary muscles. involuntary muscles. involuntary in nature. Multinucleated with light and dark They are uninucleate without Uninucleate with faint light and dark bands. bands. bands. They are attached with bones Present in vessels, esophagus. Present in wall of heart. Fibrous and un-branched, cylindrical Fibrous and un-branched, spindle Fibrous and branched, cylindrical in in shape shaped shape. 25 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Neural Tissue The unit of neural system is neuron. Neuroglial cell protect and supports the neuron. Earthworm  The common Indian earthworms are Pheretima and Lumbricus.  Earthworms have long cylindrical body divided into segments called metameres. The ventral surface contain genital pore and dorsal surface contain mid dorsal line.  First body segment is called peristomium which contain mouth. 14-16 segments are covered by dark band called clitellum.  Single genital pore is present on mid ventral line of 14th segments. A pair of male genital pore is present on 18th segment on ventro-lateral side.  All the segment except 1st , last and clitellum contain S-shaped setae for locomotion.  Alimentary canal is straight tube from 1st to last segment having, buccal cavity, muscular pharynx, oesophagus that leads to gizzards, which help in grinding the soil particles and decaying leaves. Stomach and small intestine leads to anus.  Closed vascular system consists of heart, blood vessels and capillaries. Earthworms lack respiratory organs and respire through moist skin.  Excretory organs is coiled segmental tubules called nephridia. There are three types of nephridia. Septal nephridia, integumentary nephridia and pharyngeal nephridia.  Earthworm is hermaphrodite. Two pairs of testis is present 10th and 11th segment. Prostrate and spematic duct open to surface as male genital pore on 18th segment.  One pair of ovaries is attached to the intersegmental septum of 12th and 13th segments. Female genital pore open on ventral side of 14th segment. Mutual exchange of sperms takes place during mating.  Mature sperms and egg cells along with nutritive materials are deposited in cocoon in the soil where fertilization takes place. Cockroach (Periplaneta Americana)  Cockroaches are nocturnal omnivorous organism that lives in damp places everywhere. The body of cockroach is segmented and divisible into head, thorax and abdomen. The body is covered by hard chitinous exoskeleton.  Head is triangular in shape formed by fusion of six segments to show flexibility. Head bears compound eyes. Antenna attached on head help in monitoring the environment.  Thorax consists of three parts- prothorax, mesothorax and metathorax. Forewings and hind wings are attached with thorax. Abdomen consists of 10 segments. Digestive System of Cockroach-  Alimentary canal is divided into foregut, midgut and hindgut. Food is stored in crop used for storing the food. Gizzard help in grinding the food particles.  At the junction of midgut and hindgut yellow coloured filamentous Malpighian tubules are present which help in excretion.  Blood vascular system is open type having poorly developed blood vessels. The haemolymph contains colourless plasma and haemocycts.  Respiratory system consists of network of trachea which open through 10 pairs of spiracles on lateral side. 26 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Cockroaches are dioecious. Male reproductive system consists of a pair of testes one lying on each lateral side in 4th – 6th abdominal segments. The female reproductive system consists of two large ovaries situated on 2nd – 6th abdominal segments.  The fertilized eggs are encased in capsule called ootheacea. 9 to 10 ootheace are produced by each female. Frog (Rana tigrina) Frogs are cold-blooded organism having ability to change colours to hide from enemies. Body is divisible into head and trunk, bulged eyes covered by nictating membrane. Male frog is different from female having vocal sacs and copulatory pad on first digit of forelimb.  Digestive system consists of alimentary canal and digestive glands.  Skin acts as aquatic respiratory organs. On land skin, buccal cavity and lungs acts as respiratory organs.  Heart is 3-chambered. Blood consist of plasma and blood cells. RBC is absent. 8. CELL: STRUCTURE AND FUNCTIONS  Study of form, structure, and composition of cell is called cytology.  Cell is the structural and functional unit of life.  Melthias Schleiden and Theodore Schwann( 1938) proposed the cell theory. (a). All living organisms are composed of cells and products of cells. (b). All cells arise from pre-existing cells. Prokaryotic cells Eukaryotic cells (i) Membrane bound nucleus is absent. (i) Membrane bound nucleus is present. (ii) Single chromosome is present. (ii) More than one chromosome is present. (iii) Membrane bound organelles are absent. (iii) Membrane bound organelles are present. Mycoplasma is the smallest cell and largest isolated cell is the ostrich egg. Prokaryotic Cells  Prokaryotic cells are represented by Bacteria, Blue green algae, Mycoplasma and PPLO. They multiply rapidly and vary in size greatly. All prokaryotic cells have cell wall surrounding the cell membrane except in Mycoplasma. Genetic material is naked.  Cell organelles like Mitochondria, Golgi bodies etc. are absent in prokaryotes. A specialized differentiated cell membrane called Mesosome is the characteristic of prokaryotes.  In bacterial cell a chemically complex cell envelope is present, which consist of three layers. The outermost is Glycocalyx, middle one cell wall and inner innermost is the cell membrane.  Glycocalyax may be as loose sheath in some bacteria called slime layer. In some other bacteria Glycocalyx may be thick and tough called capsule. 27 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Plasma membrane is semi-permeable having mesosome in form of vesicles, tubules and lamellae. They help in cell wall formation, DNA replication and distribution to daughter cells.  Motile bacterial cell contain flagella, which is composed of filament, hook and basal body. Pili and fimbriae are the other surface structure that help the bacteria in attach with host and other substance.  In prokaryotes, ribosome are attached with cell membrane having two sub-units – 50S and 30S to form together 70S prokaryotic ribosomes.  Ribosomes are site of protein synthesis. Ribosomes attached with mRNA to form a chain called polyribosomes.  Reserved materials in prokaryotic cells are present in cytoplasm as cell inclusion bodies, which may contain phosphate, granules, glycogen granules etc.  Gas vacuoles are found in blue green algae and purple and green photosynthetic bacteria. Eukaryotic Cell  Eukaryotic cells are present in Protista, plants, Animals and Fungi.  Plants cells differ in having cell wall, plastids and large central vacuole as compared to animal cells. Animal cells have centrioles, which are absent in plant cells.  Cell membrane is composed of lipids and that are arranged in bilayer. A lipid component is mainly composed on phosphoglycerides. Later it was found that protein is also present in cell membrane. Ratio of protein and lipids varies in different cells.  Membrane protein may be integral or peripheral. Integral protein remains buried in membrane but peripheral protein lies of surface.  Singer and Nicholson (1972) proposed fluid mosaic model. According to this model the quasi-fluid nature of lipid enables lateral movement of within the bilayer of lipids.  The main function of plasma membrane is the transport of molecules across it. Active Transport Passive Transport (a). The transport involves an expenditure of (a). The cells do not spend energy in passive transport. energy by the cells (b). It occurs against the concentration gradient. (b). It always occurs along the concentration gradient. (c). It is rapid process (c). It is comparatively slow process.  The movement of water from higher concentration to lower concentration by diffusion is called osmosis.  Cell wall is present in plant cells and fungi. Algae have cell wall made up of cellulose, galactans and minerals like calcium carbonate.  Plasmodesmata connect the cytoplasm of neighboring cells.  Endomembrane system of cell includes endoplasmic reticulum, golgi complex, lysosomes and vacuoles. Endoplasmic Reticulum Are the tubular scattered structure scattered in the cytoplasm. (i) Rough endoplasmic reticulum bears ribosomes on its surface. RER is involved in protein synthesis and secretion. (ii) Smooth endoplasmic reticulum does not bear ribosomes on its surface. SER is involved in lipid synthesis and steroidal hormones. 28 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Golgi apparatus was first observed by Camillo Golgi in 1898 near nucleus. Golgi apparatus is the site for synthesis of Glycoprotiens and glycolipids. Lysosomes are membrane bound vesicular structure formed by process of packaging in the Golgi apparatus. They are rich in hydrolytic enzyme- lipase, protease, carbohydrases active at acidic pH. These enzymes are capable of digesting carbohydrates, proteins, lipids and nucleic acids. Vacuoles are membrane bound space found in cytoplasm water, sap and excretory product bounded by single membrane. They form contractile vacuole and food vacuole in many organisms. Mitochondria double membrane bound structure with the outer membrane and inner membrane dividing its lumen in two compartments. The inner membrane forms a number of infoldings called cristae towards the matrix. Mitochondria are sites for aerobic respiration. Plastids are found only in plant cells and Eugleoids having specific pigments to provide colours to plants parts.  Chloroplast contains chlorophyll that traps solar energy for photosynthesis. Chromoplast provides yellow, orange and red colours to different parts of plants.  Leucoplasts are colourless plastids that store food, amyloplasts (carbohydrates), elaioplasts (oils) and aleuroplasts (proteins). Chloroplasts are double membrane structure. The space limited by inner membrane is called stroma. Thylakoids are present in stroma as stacks like the piles of coins called grana. Stroma contain enzyme for synthesis of protein and carbohydrates. Double strand circular DNA and ribosomes are also present in stroma. Ribosomes are granular structure of 80S. Centrosomes is an organelles containing two cylindrical structures called centrioles. Each centrioles is made up of 9 fibrils of tubulin protein. Central parts of centriole is called hub and peripheral fibrils are called spokes. Nucleus has highly extended, elaborate nucleoprotein fibres called chromatin, nuclear matrix and nucleoli. The outer membrane is continuous with endoplasmic reticulum and bears ribosomes. The chromatin materials change into chromosome during active cell division consists of DNA and histone proteins. Every chromosome has a primary constriction or the centromere, on the sides of which disc shaped kinetochores are present. On the basis of position of centromere chromosomes are of following types- 29 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes  Some chromosomes have non-staining secondary contraction at certain location. This give a small fragment called satellite. 9. BIOMOLECULES  Chemicals or molecules present in the living organism are known as biomolecules. Biomolecules are divided into two types- inorganic and organic.  Inorganic biomolecules includes minerals, gases and water and organic biomolecules includes carbohydrates, fats, proteins, nucleic acids, vitamins etc.  Proteins are polymers of amino acids.  I u lei a ids, the phosphate ole ules li ks C of suga of o e u leoside to the C of suga of e t u leosides eleasi g t o ate ole ules to fo - phosphodieste o d.  In polysaccharides, the mono-saccharides are linked by glycosidic bonds formed by dehydration between two carbon atoms of two adjacent monosaccharaides. Carbohydrates (Polysaccharides)  Polysaccharides are long chain of sugar containing different monosaccharaides as a building block.  Starch is present in plants as store house of energy in plants. It forms helical secondary structure to hold the I2 molecules.  Cellulose molecules contain glucose molecules joined together by 1- β li kage. It is the ost a u da t organic molecules on earth.  Glycogen is called animal starch as it is the reserve food materials for animals, bacteria and fungi. Glucose molecules are arranged in highly branched bush like chain having two types of linkage 1- α i st aight hai and 1-6 linkage in branching. Proteins These are polypeptide chains made up of amino acids. There are 20 types of amino acids joined together by peptide bond between amino and carboxylic group. There are two kinds of amino acids. (a). Essential amino acids are obtained by living organism along with food. (b). Non-essential amino acids can be prepared by our body from raw materials. 30 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Collagen is the most abundant protein in animal world. Primary structure of protein is the basic structure of protein in which a number of polypeptides are involved having sequence of amino acids. Secondary structure protein threads forms helix. There are three types of secondary structure- α heli , β pleated and collagen. In Tertiary structure long protein chain is folded upon itself like a hollow woolen ball to give three dimensional view of proteins. In Quaternary structure each polypeptide develops its own tertiary structure and function as subunit of protein. Eg. Hemoglobin. Nucleic Acid Nucleic acids are polynucleotides. A nucleic acid has three chemically distinct components- heterocyclic compound (nitrogenous base), polysaccharides (ribose/ deoxy-ribose sugar) and phosphate or phosphoric acid. There are two kinds of nitrogenous bases - purines and pyrimidines. Purines: Adenine and Guanine Pyrimidines: Cytosine,Thymine and Uracil. The sugar found in nucleic acid is either ribose or deoxyribose. Nucleic acid containing deoxyribose sugar is called DNA (Deoxyribonucleic Acid) and those containing ribose sugars are called RNA (Ribonucleic acid). Metabolic Basis for living organism: The metabolic pathways that lead to more complex structure from simpler structure are called biosynthetic or anabolic pathways and those pathways that lead to simpler structure from complex structure are called catabolic pathways. Enzymes  Enzymes are commonly proteinaceous substances which are capable of catalyzing chemical reactions of biological origin without themselves undergoing any change, commonly called as biocatalysts. The nucleic acids that behave like enzymes are called ribozymes.  The major difference between inorganic and organic catalyst is inorganic catalyst works effectively at high temperature and pressure but enzyme get damaged at high temperature.  The external energy required to start a chemical reaction is called activation energy. Factors influencing Enzyme Activity (a). Temperature (b). pH (c) Concentration of Substrate Competitive Inhibitor- When the molecular structure of inhibitor resembles the substrate that inhibits the function of enzymes.  Enzymes are classified as o Oxidoreductases/Dehydrogenases - o Transferases o Hydrolases o Lyases o Isomerases o LIgases 31 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes Co-factors are the non-protein constituent of an enzyme to make the enzyme catalytically more active. The protein portions of enzyme are called apoenzymes. There are two types of cofactors: Coenzymes Prosthetic groups. The essential chemical components of any coenzymes are vitamins. As NAD and NADP contains vitamins niacin. 10. CELL CYCLE AND CELL DIVISION Phases of Cell cycle Human cell divides once in approximately 24 hours, which may vary in different organisms. In yeasts it takes about 90 minutes to complete the cell division process. (a). Interphase- It is the phase between two successive M phases. Interphase lasts for 95% of a cell cycle. This phase is called as resting phase but during this period the cells prepare its self for nuclear division by cell growth. (b). M Phase- When the actual cell division or mitosis occurs. It starts with karyokinesis (nuclear division) or duplication of chromosome and end with cytokinesis or division of cell matrix (cytoplasm division).  G1 phase represents the interval between mitosis and initiation of DNA replication.  During S phase, replication or synthesis of DNA takes place and amount of DNA get doubles per cell.  During G2 phase protein is synthesized in preparation for mitosis.  In adult animals, some cells do not divide or may divide occasionally. These cells do not divide further and exits the G1 phase to enter an inactive stage called Quiescent Stage (G0) of cell cycle.  Mitosis cell division is also known as equational division. Prophase is the first phase of mitosis followed by G2 phase. It involves following events- (a) Initiation of condensation of chromosomal materials. (b) Movement of centrioles towards opposite poles of the cell. (c) At the end of prophase, endoplasmic reticulum, nuclear membrane, Golgi complex disappears. Metaphase starts with complete disappearance of nuclear membrane. The most suitable stage for study of morphology of chromosomes. It involves (a) Condensation of chromosomal materials in to compact and distinct chromosomes made up of two sister chromatids attached with spindle fibres with kinetochores. (b) Chromosomes arrange at centre of cell called metaphase plate. Anaphase involves the (a) Splitting of each chromosome at centromere into two sister chromatids. 32 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes (b) Two chromatids start moving towards opposite poles. Telophase is the last stage of mitosis which involves (a) Chromosomes reach at opposite poles and loose its identity as discrete unit. (b) Nuclear membrane reassembles around the chromosome clusters. (c) Nucleolus, Golgi complex and ER reappear. Cytokinesis is the division of cytoplasm of a cell after karyokinesis (division of chromosome) into two daughter cells. Meiosis The cell division that reduce the number of chromosome half and results in the production of haploid daughter cells. It helps in production of haploid phase of life cycle of sexually reproducing organism. It involves following events. (a) Two sequential cycles of nuclear and cell division called meiosis I and meiosis II but single cycle of DNA replication. (b) It involves pairing of homologous chromosome and recombination of them. (c) Four haploid cells are formed at the end of meiosis II. Meiosis I Meiosis II Prophase I Prophase II Metaphase I Metaphase II Anaphase I Anaphase II Telophase I Telophase II Meiosis I Prophase I of Meiosis is the first stage of meiosis and is defined by five different phases; Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis. In metaphase I, the bivalent chromosome align at equatorial plate and microtubules from the opposite poles of the spindle attached to the pair of homologous chromosomes. In Anaphase I, homologous chromosome separate but sister chromatids remain attached at centromere. During Telophase I, nuclear membrane and nucleolus reappears and cytokinesis follows. This is called as dyad of the cells. The stage between two meiotic divisions is called interkinesis and it is short lived that follows Prophase II. Meiosis II It is initiated immediately after cytokinesis before chromosome gets elongated. In prophase II, nuclear membrane disappears and chromosome becomes compact. At metaphase II stage, the chromosomes align at equator and microtubules attach with kinetochores of sister chromatids. Anaphase II start with splitting of centromere of each chromosome to move towards opposite poles. Meiosis ends with Telophase II in which two groups of chromosomes get enclosed by nuclear membrane followed by cytokinesis to form tetrad of cells (four daughter cells). 33 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes 11 TRANSPORT IN PLANTS Long distance transport occurs through vascular system, xylem and phloem phloem called translocation through mass flow. The direction of translocation may be unidirectional as in case of water and multidirectional as in minerals and organic solutes. Simple Diffusion- Mo e e t diffusio is passi e and flows along the concentration gradient through permeable membrane. No energy expenditure takes place. It occurs in liquid and gases. Rate of diffusion are affected by gradient of concentration, permeability of membrane, temperature and pressure. Facilitated Diffusion- Lipid soluble particles easily pass through cell membrane but the hydrophilic solutes movement is facilitated. For facilitated diffusion, membrane possesses aquaporins or water channels. Aquaporins are membrane proteins for passive transport of water soluble substances without utilization of energy. The porins are proteins that forms huge pores in the outer membrane of the plastids, mitochondria etc. Symport, Antiport and Uniport- In Symport, both molecules cross the membrane in the same direction. In Antiport, both molecules moves in opposite direction. When a molecule moves across a membrane independent of other molecules, the process is called uniport. Active Transport Uses energy to pump molecules against the concentration gradient. It is carried out by membrane proteins. In active transport, movable carrier proteins are called pumps. The pumps can transport substance from low concentration to high concentration. The carrier proteins are very specific in what it carries across the membrane. Plant Water Relationship Terrestrial plants take lot of water and release most of it in form of water vapour by the process of transpiration. Water Pote tial Ψw - Water potential is determined by solute potential (Ψs) and pressure potential (Ψp.  Water molecules possess kinetic energy. The greater the concentration of water in the system, the greater is its kinetic energy or water potential. So pure water has greatest water potential.  Water potential is denoted by Greek symbol Psi (Ψ and is expressed in pressure unit Pascal (Pa).  Water pressure of pure water is taken as zero at standard temperature and pressure. A solution has less water potential due to less water concentration.  The magnitude of lowering of water potential due to dissolution of solute is called solute potential (Ψs ). Solute potential is always negative. More the solute molecules in the solution lesser the solute potential.  If a pressure greater than atmospheric pressure is applied to pure water or solution, its water potential increases. Pressure potential is usually positive. Pressure potential is denoted by (Ψp.  Water potential of a cell is affected by both solute and pressure potential. The relationship is as follows. 34 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes o Ψw = Ψs + Ψp Osmosis is the diffusion of water across a semipermeable membrane. The net direction and rate of osmosis depends upon the pressure gradient and concentration gradient. Water will move from its region of higher concentration to region of lower concentration until equilibrium is reached. Osmotic potential is the pressure required to prevent water from diffusing. More the solute concentration greater will be the pressure required to prevent water from diffusing it. Numerically osmotic pressure is equal to osmotic potential but sign is opposite. Osmotic pressure is the positive pressure while osmotic potential is negative. If the surrounding solution balances the osmotic pressure of cytoplasm, the solution is called isotonic. If the external solution is more dilute than cytoplasm, it is hypotonic. The cells swell up when placed in hypotonic solution. If the external solution is more concentrated than cytoplasm, it is hypertonic. Cell will shrink in hypertonic solution. Plasmolysis is the shrinkage of the cytoplasm of the cell from its cell wall under the influence of hypertonic solution. The pressure of plasmolysis is usually reversible when the cell is placed in hypotonic solution. The pressure build up against the wall due to movement of water inside is called turgor pressure. It is responsible for enlargement and extension growth of cells. Imbibition is a special type of diffusion when water is absorbed by solid colloids causing them to increase in volume. For example absorption of water by seeds and dry woods. Imbibition is also a kind of diffusion because movement of water is from higher concentration to lower concentration. Water potential gradient between the absorbent and liquid imbibed is essential for imbibition.  Long distance transport of water in plants takes place by mass or bulk flow system. It is the movement of substance in bulk from one point to another as a result of pressure difference between two points.  The bulk movement of substances through the conducting or vascular tissue of plants is called Translocation. Xylem is associated with translocation of water and mineral salts, some organic nitrogen and hormone from roots to aerial parts of plants.  Phloem transport organic and inorganic solutes from leaves to other part of plants. Absorption of water by plants Water is absorbed along with mineral solutes by roots hairs by diffusion. The absorbed water passes to deeper layer of by two pathways. Apoplast pathway and Symplast pathway Apoplast pathway consists of nonliving parts of plants body such as cell wall and intercellular spaces whereas Symplast pathway consists of living parts of plant body such as protoplast connected to plasmodesmata. Most of the water flows in roots via apoplast pathway because cortical cells are loosely packed and offers no resistance to water movement. The inner boundary of cortex, endodermis is impervious to water due to suberized matrix called Casperian strip. Water molecules are directed through wall regions that are not suberized. Water flows through the different layers of roots to reach the xylem tissues as follows- A mycorrhiza is the symbiotic association between a fungus and angiosperic roots. The fungal filaments forms a network around the young root to have large surface area that mineral ions and water from the soil. The fungus provide minerals and waters and roots in turn provide organic and nitrogen containing compounds. Ascent of sap (Translocation of water) 35 WWW.JEEBOOKS.IN Downloaded From www.jeebooks.in Biology Short Notes The upward movement of water from roots towards the tips of stem branches and their leaves is called ascent of sap. Theories of Ascent of Sap  Vital force theory was forwarded by J.C.Bose in 1923. This theory believes that the innermost cortical cells of the root absorb water from the outer side and pump the same into xylem channels.  Root pressure theory was forwarded by Priestley in 1916. Root pressure is positive pressure that develops in the xylem sap of the root of plants. It can be responsible for pushing up water to small heights in plants. Loss of water in liquid phase by herbaceous plants from the tips of leaf blades is known as guttation.  Water rises in tubes of small diameters, kept in vessels having water due to force of surface tension. Similarly water rises up in the walls of xylem channels due to adhesion and cohesion. This theory is called Theory of Capillarity.  Cohesion Tension theory was put forwarded by Dixon and Joly in 1894. According to this theory water is mostly pulled due to driving force of transpiration from the leaves. The water molecules remain attached with one another by cohesion force. The water molecule does not breaks in vessels and tracheid due to adhesive force between their walls and water molecules. On account of tension crated by transpiration, the water column of plant is pulled up passively from roots to great heights. Transpiration is the loss of water in form of water vapour from aerial parts of plants. Phloem transport: Flow from Source to Sink  Food (sucrose) is transported by phloem form source to sink. The part of plant that synthesize the food is called source and part where food is used or stored.  The source and sink can be reversed by the pla ts depe di g upo the seaso o pla t s need. So, the direction of movement in the phloem is bi-directional.  Phloem sap is mainly water and sucrose but other sugars, hormones and amino acids are also translocated through it. Pressure flow or Mass flow hypothesis  It is the most accepted theory for the translocation of sugar from source to sink. Glucose is prepared at source by photosynthesis which is converted into disaccharides (sucrose). Sucrose moves into companion cells and then into sieve tube cells by active transport.  Loading of phloem at source creates a water potential gradient that facilitate the mass movement in the phloem.  Sieve tube cells of phloem forms a long column with holes in their wall called sieve plates