Education is the key to success • 247 . CHAPTER - 1 THE LIVING WORLD • The living world comprises of diverse type of organisms. • Growth • Biology is the branch of science which deals with the study of living things. Ar- istotle is considered as the founder of growth. • • • Increase in mass The term biology is proposed by Lamarck. Increase in number Biology is divided into 2 main branch- Multicellular organisms –grow by cell di- es—Botany and Zoology. vision. Botany is a Branch of biology which • Aristotle is considered as the “father of • ter, cell division is seen in certain tissues Theophrastus is considered as the to replace the lost cells. “father of botany”. He was a student of • Aristotle. • • These non living objects are grown by the living things from non living things. accumulation of material on their surface. Characteristics of living organisms. Therefore growth cannot be taken as a defining property of living organisms Basic characteristics exhibited by living organ- alone. A dead organism does not grow isms are growth, reproduction, ability to ganization, and consciousness. Non living objects such as mountains, boulders, sand mounds, etc also grow. Life is the property that distinguishes sense environment. Metabolism, cellular or- Unicellular organisms also grows by cell division. . There are 2 types of objects in the world living and non living. • In animals, the growth by cell division occurs only up to a certain age. Thereaf- zoology”. • In plants, growth by cell division occurs throughout their life span. deals with the study of plants. • Growth of an organism has two characteristics. biology. • Increase in body mass considered as Reproduction • It is a characteristic of living organisms. In living organisms, reproduction means the Plus 1 Biology Winner’s Coaching Centre The Living World There is no substitute for hard work • 248 . • production of new individuals similar to the and respond to these environmental stimu- parents. li. Which could be physical, chemical and biological. A multicellular organism reproduces by 3 ways—sexual, asexual and vegetative, method. Examples:• Examples Human beings sense the environment through sense organs. • Fungi—asexual spores • Hydra and yeast—budding • Planaria—regeneration • Plants respond to external factors like light, temperature, water, pollutants, other organisms etc. • • Filamentous algae & fungi— ( duration of light) affects the reproduction fragmentation. • In both plants and animals, photo period in seasonal breeders. In unicellular organisms like bacteria, • A human being is the only organism hav- amoeba, unicellular algae etc reproduction ing ” selfconsciousness” ie aware of him- is synonymous with growth, ie increase in self…therefore number of cell. • Metabolism • the livingorganisms. The sum total of all the chemical reactions • sharing of common genetic material to Metabolism is a defining feature in all liv- varying degree. ingorganisms. Diversity in the living world Cellular organization • All unicellular or multicellular organisms • life in the world. Cellular organisaton of the body is the defining feature of life forms. • Biodiversity. All living organisms have the ability to sense their surroundings or environment Plus 1Biology This natural diversity of life on earth is generally called biological diversity or Consciousness • All living organisms which live on earth together make up the natural diversity of are madeup of one or more cells. • All living organisms (present , past and future) are linked to one another by the occuring in our body is called metabolism. • consciousness is the defining property of TAXONOMY • The branch of science which deals with Winner’s Coaching Centre The Living World Always have an attitude of gratitude • 249 . identification, nomenclature and classifica- • Anyone can study, describe, identify and tion of organisms is called taxonomy or give a name to an organism provided cer- systematics. tain universal rules are followed NOMENCLATURE • These rules codes) are framed and stand- • Method of naming is called nomenclature. • Naming of living organisms is one of the ICBN- International Code for Botanical important features of taxonomy. Nomenclature • Names may be of 2 types. ICZN- International Code for Zoological Local names and scientific names. Nomenclature 1) Local names • ardized by the following organizations. Biological names are generally in Latin and written in italics. They are Locally used names are called local names latinised or derived from Latin irre- ( vernacular names or common names) spective of their origin. • These names vary from place to place. • These names created confusion because the genus whereas second one is for different species may be known by the species. same name. 2) 3) to indicate their latin origin. It is a method of naming by which an organism is known by a scientific name having 2 components (words). • 4) Generic name starts with a capital let ter and the specific name with a small letter It was first introduced by Carolus Linnaeus . in1758 • Names are printed in italics or when hand written are separately underlined Binomial nomenclature • First word of a biological name denotes Eg:- Mangifera indica, Homo sapiens. In a binomial name, the first component (word) is called generic name or genus 5) The name of the author is written in ab name and the second component (word) is breviated form after the species name called specific name or species name. and is printed in roman.(eg: Mangifera indica Linn.) it indicates that this spe cies was first described byLinnaeus. Plus 1Biology Winner’s Coaching Centre The Living World Be the light for your family • 250 . Classification • Taxonomic categories It is the process by which anything is • Plants and animals are placed in a series or grouped intoconvenient categories based succession of different ranks or categories on some easily observable characters. according to their natural relationship Biological classification Taxonomic hierarchy (hierarchy of The scientific method of an arrangement of organisms into groups is called biological classification. categories) • It is a system of classification in which a group of things are ranked one above the Taxonomy other. In this system seven taxonomic categories are placed one above the other. • It is a branch of biology which deals with identification, nomenclature and classifi- The categories are.. cation of organisms. • Taxonomy is based on… • Kingdom, phylum or division, class, order, family,genus and species. Characterisation Taxon :- each category in the taxonomic hier- • archy is called a taxon. It represents the Identification actual biological objects placed in a cate• Classification and • Nomenclature gory. The modern taxonomic studies are based on • External and internal structure • Structure of cell • Developmental processes • Ecological information Plus 1Biology Winner’s Coaching Centre The Living World Be giving, enjoy sharing • 251 . Seven taxonomic categories. • genus Felis which includes cats. Species It is a group of individuals resembling one another in all major vegetative and reproductive characters (A species is a group of individuals Family • isolated andsimilar in morphological character- A family is an assemblage of related genera.Examples: which are genetically distinct, reproductively • istics). • The genus Panthera differs from another The lion (Panthera leo) and the house cat (Felis domestica) belonging to two different genera are included under the It is the lowest taxon in biological classi- family Felidae. fication. Order or cohort • E g: - Mangifera indica (Mango) Solanum tuberosum (Potato) • An order is a category of related families. • Example families like Felidae (lion, tiger, Panthera leo (Lion) • • leopard,cat etc.) and Canidae (dogs and The names indica, tuberosum and leo represents specific names. The names Mangifera, solanum and panthera represents generic names. foxes) are placed under the order carnivora. • Plant families like Convolvulaceae and Solanaceaeare included in the order poly- • The scientific name of human being- Homo sapiens Genus moniales. Class • • Several related orders having certain common characters form a higher category A genus is a group of related species. called the class. • All the species in a genus have many common characteristics. For example, the genus panthera includes species such as lion • Example the order carnivora and the order primata are included in the clas Mammalia (Panthera leo), leopard (Panthera pardus), and tiger (Panthera tigris) with many common features. Plus 1Biology Winner’s Coaching Centre The Living World Dedication is expensive than talent • 252 . Phylum or Division • Herbarium Classes having same features in common A herbarium is defined as store house of col- constitute a phylum. lected plant specimens which have been dried, pressed, preserved on herbarium sheets, and • For example phylum chordata include a arranged in the sequence of a universally ac- number of classes such as pisces, am- cepted system of classification. phibia, reptilia, aves and mammals. • The herbarium sheets also carry a label provid- The classes such as Dicotyledonae, mono- ing information about date and place of col- cotyledon, are included in the division of lection. Angiospermae. English, local and botanical names, family,collectors name etc.. Kingdom Herbarium label The highest category in the biological clas- • sification is the kingdom. It includes one or more related divisions or phyla. Plants are kept in a kingdom plantae and • animals are put in the kingdom animalia. Com- Biolog- mon ical Name Name Man Homo Genus Musca fly domes- Order Class Phylum / Division Homo saplens House- Family Hom- Primata inidae Musca Musci- Mamm Chordata alta Diptera Insecta Arthropoda • dae is published in the form of a book called tica Mango Man- Man- Ana- Sapin- Dicoty- gifera gifera cardiac dales ledonae indica Wheat Triti- Poace- cum cum ae aes- flora. Angiospermae eous Triti- Information about the collected specimens • Poales Mono- It gives a list of total plant species in a particular region together with a brief descrip- Angiospermae cotyled tion of the same. on tivum • Plus 1 Biology The largest herbarium of the world is Her- Winner’s Coaching Centre The Living World Today a reader, Tomorrow a leader • 253 . barium of royal botanical garden at Kew in England. • Manuals These provide an information for identification The largest herbarium in India is central national herbarium. of names of species occurring in an area. Monograph Taxonomic keys These provide the information of any one tax• A key is a tool by which each species in a group of organisms may be identified. • It is prepared by a taxonomist to help other biologists to identify the species. • Catalogue These provide the list of publications. The publications publish the books, periodicals and Taxonomic keys are based on contrasting characters. • on. dictionaries which provide new information for taxonomic studies IMPORTANT QUESTIONS The characters are in a pair called couplet. 1. • Separate taxonomic keys are required for ICZN and ICBN each taxonomic category like family, genus and species for their identification • Expand the following terms. 2. The scientific name of housefly and wheat are given below. Correct them. Besides the above mentioned taxonomic aids , flora, manuals, monographs (a) Musca Domestica and catalogues also serve as taxonomic tivum aids for correct identification. 3. (b) Triticum Aes Select a proper genus and species name in order to get correct scientific name of Flora the following animals from the table giv en below. • These contain the actual account of habitat and distribution of plant species of a given area. • It provides the index to plants occuring in a particular area. Plus 1 Biology Winner’s Coaching Centre The Living World Performance comes from practice • 254 . 4. Generic Species name name Mangifera Sapiens Panthera Indica Musca Leo Homo domestica PREVIOUS YEARS QUESTIONS 9. Align the taxonomic categories in the acending order. Genus, Order, Phylum, Species, Family, Class, Kingdom. List the advantages of the following: 10. (a) Taxonomic key (b) Herbarium 5. Complete the table using suitable terms. Com- Complete the table. mon Genus Species Class Phylum Name Sl. No. 1. Common Biologiname cal name ……... Panthera Class 6. Mango …... Sapi- Mam- —— 11. Rearrange the following taxonomic cate …... gories in the correct sequence. Kingdom Class Phylum Genus Fill in the blanks . Family Order Species Species → ……. (a)…...→Family → Order ……(b)….. Phylum → Kingdom. 7. —— …... leo 2. Man 12. Binomial nomenclature was proposed by……. Panthera leo (a) Identify the naming system used. 13. Unit of classification is………. (b) What do the two terms indicate? 8. The Hierarchical arrangement of taxo nomic category of housefly is given be low. Rewrite it correctly. (a) Taxon (b) Species (c) Genus (d) cell ANSWERS Muscidae → Diptera → Musca → Insec ta → domestica → Arthropoda → 1. ICZN - International Code of Zoological Nomenclature. ICBN - International Code of Botanical Plus 1 Biology Winner’s Coaching Centre The Living World Knowledge increases by sharing • 255 . Nomenclature. 2. (a) Musca domestica 5. (b) Triticum aes- tivum Sl. No. Common Biologiname 3. 1. Generic Lion Species cal name Panthera Mango Man- Dicotyledonae Mangifera indica gifera Panthera leo indica Musca domestica Homo sapiens 6. (a) Genus Carnivora Leo 2. Class (b) Class 7. (a) Binomial nomenclature 4. (a) 1. Each species in a group of organisms (b) Genus and species 8. Domestica → Musca → Muscidae → Dip- may be identified. 2. To help other biologists to identify the species. tera → Insecta → Arthropoda 9. Species → Genus → Family → Order → (b) 1. It serves as quick referral system in taxonomic studies. Class → Phylum → Kingdom. 10. Homo, Chordata 2. It is a permanent and ready record of plant specimen. 11. Kingdom Phylum Class Order Family Genus Species. 3. It is used for knowing our bio - re sources and biodiversity. 12.Carolus Linnaeus 13. Taxon Plus 1 Biology Winner’s Coaching Centre The Living World Keep calm and respect others • 256 . CHAPTER 2 BIOLOGICAL CLASSIFICATION Classification:- The arrangement of anything eukaryotes and prokaryotes into groups is called classification. ii) It does not distinguish between unicellular Biological classification:- the scientific method of arrangement of organisms into groups is called biological classification. • organisms and multicellular organisms. iii) It does not distinguish photosynthetic organisms (eg: green algae) and nonphotosynthetic organisms (eg: fungi). Aristotle was the first to attempt a scientific classification of organisms. • Based on morphology (external character- iv) Included bacteria, blue green algae, and fungi in Kingdom Plantae along with oth- istics) he classified plants into three er plants because of the presence of cell groups-trees, shrubs and herbs. • wall. But bacterial cell wall, plant cell wall He classified animals into two categories and fungal cell wall differ from each other red blooded and non-red blooded in their constitution. v) Two kingdom classification • into either of the categories of the two kingdom classification. Carolus Linnaeus proposed the two kingdom classification and the classification was used till recently. • A large number of organisms did not fall Five kingdom classification In 1969, R.H. Whittaker proposed the five- According to this system organisms are kingdom classification. He classified the living classified into two large groups organisms into five kingdoms. The criteria used by Whittaker are given below. (i) Kingdom plantae (Plant Kingdom) (i) Kingdom Animalia (Animal Kingdom) Drawbacks of the Two Kingdom Classification i) The system did not distinguish between Plus 1 Biology • Cell structure • Thallus organisation • Mode of nutrition • Reproduction • Phylogenetic relationships Winner’s Coaching Centre Biological Classification Whatever you are, be a good one • 257 . The five kingdoms of living organisms are given below. 1. Kingdom Monera 2. Kingdom Protista 3. Kingdom Fungi isms. 2. Kingdom Protista • unicellular aquatic eukaryotic organisms. • 4. Kingdom Plantae 5. Kingdom Animalia The Kingdom Protista includes primarily The cells of protists have true nucleus and other membrane-bound organelles and non membraneous organelles Different characteristics of the five kingdoms 3. Kingdom Fungi • The Kingdom Fungi includes eukaryotic, multicellular, heterotrophic organisms (Yeast is an exceptional fungus which is unicellular). 4. Kingdom Plantae • The Kingdom Plantae (plants) includes multicellular, chlorophyll-containing organisms. • They are immobile (No locomotion), cell wall is composed of cellulose. 5. Kingdom animalia • It includes multicellular heterotrophic eukaryotes. They show locomotion. Cells 1. Kingdom Monera • are without cell wall. All prokaryotic organisms are included in Merits of five kingdom classification the kingdom monera. 1. This classification is based on cellular • They are microscopic organisms. • True nucleus and other membrane-bound characters which evolved very early in cell organelles are absent in these organ- the organic world. Plus 1 Biology organisation and modes of nutrition, the Winner’s Coaching Centre Biological Classification There is no substitute for hard work • 258 . 2. In this classification, the organisms are placed based on the gradual evolution of early organisms into plants and animals. 3. All prokaryotic organisms are grouped otes.They are divided into three groups. 1. Halophiles-bacteria living in salty areas 2. Thermoacidophiles-They are temperature and acid loving bacteria and live in hot together under Kingdom Monera 4. The eukaryotic unicellular organisms are grouped under Kingdom Protisa. 5. springs. 3. Methanogens-found in marshy areas and in the guts of several ruminant animals Green plants have cellulosic cell wall like cows and buffalos. They are responsi- (cell wall with cellulose) while fungi ble for the production of methane (biogas) have chitinous cell wall (cell wall with from the dung of these animals. chitin), Green plants are autotrophs while fungi are heterotrophs. Based on these Eubacteria (True bacteria) differences, the fungi were placed in a separate kingdom - Kingdom Fungi, and cyanobacteria. KINGDOM MONERA • They are true bacteria which include bacteria They are unicellular microscopic and (i) Bacteria prokaryotic • They lack definite nucleus and membrane bound organelles. • They are unicellular microscopic monerans. Based on their shape, bacteria are grouped into 4 categories - Coccus, Bacillas, Vibrium and Rigid cell wall present (made of polysac- Spirillum charides and aminoacids) 1. Coccus ( cocci)-Spherical shaped bacte- • Nutrition-heterotrophic or autotrophic • Bacteria are the sole members of this in pairs (eg: Diplococcus) or in groups(eg: kingdom. staphylococcus) Monerans are classified into three groups. (i) archaebacteria (ii) eubacteria (iii) mycoplasma rium. It may occur singly (eg: Monococcus) or or in long chains (streptococcus). 2. Bacillius ( bacilli) - Rod-shaped bacterium. It may occur singly ( Bacillus) or in pairs(eg: Diplobacillus) or in groups (eg: Streptobacil- Archaebacteria lus). They are an ancient group of primitive prokaryPlus 1 Biology Winner’s Coaching Centre Biological Classification Always have an attitude of gratitude • 259 . 3. Vibrium (vibrio) - Comma-shaped bacte- Heterotrophic bacteria rium. eg: Vibriocomma. They do not synthesise their own food but 4. Spirillum ( spirilla) - Spiral-shaped bacte- rium. It is spirally twisted or coiled. eg: Spiro- depend on other organisms or on dead organic matter for food. chetaes. Heterophic bacteria may be of 3 types parasitic bacteria, saprophytic, and symbiotic bacteria. Parasitic bacteria: They absorb food from the host and cause diseases on the host. eg: Cholera, typhoid, tetanus, citrus canker are diseases caused by bacteria Saprophytic bacteria: They live on the dead Nutrition in Bacteria matters and absorb food from them. Nutrition may be Autotrophic or heterotrophic. ficial association with other organisms. eg: Autotrophic bacteria Rhizobium. They synthesise their own food from inorganic substances,bacteria may be divided into 2 types-photosynthetic autotrophic bacteria and chemosynthetic autotrophic bacteria. i) Symbiotic bacteria: They form mutually bene- Reproduction in bacteria • Reproduction mainly by binary fission • Under unfavorable conditions they produce Photosynthetic autotrophic bacteria. spores. They prepare theirown food from the en• ergy obtained from the sunlight. Sexual reproduction is seen in some species through a primitive type of DNA ii) Chemosynthetic autotrophic bacteria transfer from one bacterium to another. They oxidise various inorganic substances such as nitrates,nitrites and Ammonia (ii) Cyanobacteria (blue-green algae) to release energy for their ATP produc- 1. They may be single-celled (eg: Spirulina), tion. Plus 1 Biology colonial (eg: Nostoc) or filamentous (eg: Winner’s Coaching Centre Biological Classification Be giving, enjoy sharing • 260 . Oscillatoria). saprotrophic. 2. Colonial forms of cyanobacteria are gener- • The kingdom Protista is classified in to ally surrounded by a mucilaginous sheath chrysophytes, dinoflagellates, euglenoids, (gelatinous sheath). It prevents drying of slime moulds and protozoans, the cells during desiccation. eg: Nostoc. 3. They have chlorophyll-a pigment similar to 1. Chrysophytes that of green plants. 4. They are aquatic or terrestrial 5. They form blooms in polluted water bod- • Found in fresh water and in marine habitat. • Microscopic and float passively in water cur- ies. rents(Planktons) 6. Some of the species possess specialised cells called Heterocysts. 7. Heterocysts help to fix atmospheric nitro- • Most of them are photosynthetic. • Diatoms and desmids are the major groups. gen and enrich the fertility of the soil. eg: Diatoms Nostoc and Anabaena. Mycoplasma • They are the smallest living cells on earth. • They lack cell wall and can survive with- • They are the chief producers in the ocean. • Walls are embedded with silica and so the walls are indestructible. • out oxygen. • Diatoms have left behind large amount of cell wall deposits in their habitat. This is known as diatomaceous earth. They cause many pathogenic diseases in • plants and animals. Diatomaceous earth is granular in nature, so it is used in polishing, filtration KINGDOM PROTISTA of oils etc. • Unicellular, Aquatic, Eukaryotes. 2. Dianoflagellates • Often they may possess flagella or cilia • • Cell wall, if present, made of cellulose • Nutrition: Photosynthetic, holotrophic or Plus 1 Biology They are mostly marine and photosynthetic. • They appear yellow, green, brown, blue or red in colourd Winner’s Coaching Centre depending on the major Biological Classification Make time for yourself • 261 . pigment present in their cells. leaves engulfing organic material. The cell wall contains a stiff cellulose plate on • the outer surface. They form an aggregation called plasmodium under suitable conditions. Most of them have two flagella one longitudi- • nal and other transverse. Under unfavorable conditions the Plasmodium differentiates and forms fruiting bodies. The fruiting bodies bear spores at their Red dianoflagellates (eg: gonyaulax) multiply tips. rapidly and make the sea appear red (red tides). During red tide they release toxins into the sea 5. protozoans result in the death of large number of marine animals such as fishes. • or parasites. 3. Euglenoids • Majority of them are fresh water organ- • • They have a protein rich layer called the • Amoeboid protozoans, flagellated protozoan, makes their body flexible. ciliated protozoan, sporozoans. They have two flagella, one short and the They are photosynthetic in the presence KINGDOM FUNGI • under deprived sunlight predating other Eukaryotic, unicellular (eg: Yeast) or multicellular,without chlorophyll. of sunlight but behave like heterotrophs • small organisms. • There are 4 major groups of protozoans. pellicle instead of cell wall. The pellicle other long. • They are believed to be primitive relatives of animals. isms found in stagnant water. • All are heterotrophs and live as predators Heterotrophic nutrition (Saprobes or Parasites) The photosynthetic pigments in eugle- • noids are identical to that of higher The body of the fungus is called mycelium. plants. Example: Euglena. 4. Slime Moulds A part of the mycelium is called hypha • The hyphae are septate (with cross walls) or aseptate (without cross walls). • They are saprophytic protists.. • The body moves along decaying twigs and Plus 1 Biology • • Fungi are multicellular (except yeast uni- Winner’s Coaching Centre Biological Classification Dedication is expensive than talent • 262 . cellular). Many fungi are multinucleate. Sexual reproduction The multinucleate condition is said to be The sexual cycle of fungi has 3 steps. coenocytic. • The cell wall is made up of chitin and polysaccharides. Plasmogamy: fusion of protoplasm between 2 motile or non-motile gametes. Karyogamy: Fusion of 2 nuclei. • Fungi are the major decomposers. Meiosis: Zygote undergoes meiosis to form 4 haploidspores. Nutrition in Fungi • Mostly they are heterotrohpic in nutrition • They absorb soluble organic matter from dead substrates. So they are called sapro- • • • Kingdom fungi is classified into phycomycetes, ascomycetes, basidiomycetes and deuteromycetes phytes. Phycomycetes Some depend on living plants and animals • Found in aquatic habitats and on decaying for their food.They are parasites. wood in moist and damp places or as obli- Some fungi live in symbiotic association gate parasites on plants. with algae called lichens. • Mycelium is aseptate and coenocytic Some are symbiotic with roots of higher • Asexual reproduction takes place by mo- plants called mycorrhiza. tile zoospores or by non motile aplanospoes. Reproduction • • • ospores. Zygospores are formed by fusion of two gametes. • The gametes are similar in morphology (isogamous) or dissimilar Sexual reproduction - by oospores, ascospores and basidiospores. • • Asexual reproduction - by different spores like conidia,sporangiospores or zo- • in sporangium. Vegetative reproduction takes place by fragmentation,fission and budding. These spores are endogenously produced • Examples: Rhizopus (the bread mould), Mucor. All the spores are produced in various distinct spore bearing structures called fruit- • Albugo is a parasitic fungus on mustard. ing bodies. Plus 1 Biology Winner’s Coaching Centre Biological Classification Dedication is expensive than talent • 263 . Ascomycetes of different strains. Sex organs are absent. • It is commonly known as sac-fungi. • They are unicellular or multicellular. Yeast (Saccharomyces) is a unicellular ascomycete. • • dikaryon, which ultimately gives rise to a club shaped structure called basidium. • Karyogamy and meiosis occur in the basidium resulting in the production of four Conidia are the asexual spore. They are produced exogenously on the special mycelium called conidiophores. basidiospores. • The basidiospores are exogenously produced on the basidium. • Conidia germinate to form new mycelium • Sexual spores are ascospores. They are produced endogenously in sac like asci. The asci are arranged in different type of • Examples: Aspergillus,Claviceps, • Example: Agaricus (mushroom). Ustilago (smut),Puccinia (rust fungus). Deuteromycetes • Neurospora,penicillium, yeast. The basidia are arranged in the fruiting body called basidiocarp. fruiting bodies called ascocarps. • The fusion of somatic cells results in They are known as imperfect fungi because only the asexual or Basidiomycetes vegetative phases are known. • It includes Mushrooms, bracket fungi and puff balls. • • • When sexual (perfect) stage of the members of deuteromycetes is discovered, they will be placed They inhabit soil, logs and tree stems. in ascomycetes or basidiomy- Parasitic forms are rusts and smuts in liv- cetes. ing plants • Reproduce only by asexual spores called • The mycelium is branched and septate. • The asexual spores are not found. • Mycelium is septate and branched. • Vegetative reproduction is by fragmenta- • Some are Saprophytes or parasites. Eg: tion. • conidia. Alternaria, Trichoderma etc. Sexual reproduction is brought about by fusion of two vegetative or somatic cells Plus 1 Biology Winner’s Coaching Centre Biological Classification You are good enough, respect yourself • 264 . KINGDOM PLANTAE • fat. They are multicellular chlorophyll con- • They show locomotion. • The sexual reproduction is by copulation taining autotrophic organisms. • They are eukaryotes • They have cellulose cell wall • Cells have large vacuole in the cytoplasm VIRUSES • They are immobile (no locomotion) • Viruses are non cellular organisms • Most of the members are photosynthetic. • They were discovered in 1892 by Russian • A few members are partially heterotrophic of male and female followed by embryological development such as insectivorous plants (bladder wort, biologist Iwanovsky • consists largely of proteins. Venus fly trap) or parasites (Cuscuta). • Includes algae, Bryophytes, Pteridophytes, Viruses could be crystallised and crystals • Viruses did not find a place in classification since they are not truly 'living'. They Gymnosperms and Angiosperms. are inert outside their specific host cell. • • The life cycle of plants has two distinct Viruses are obligate parasites. Viruses phases - the diploid sporophytic phase share characteristics of both living and and the haploid gametophytic phase. non-living things. Both the phases alternate with each other. Structure of viruses The phenomenon is called alternation of • generations. protein coat called capsid and genetic ma- KINGDOM ANIMALIA • terial (DNA or RNA). They are multicellular heterotrophic eu- • karyotes. Capsid - The protein coat of virus is called capsid. • The cells are without cell wall • They lack chlorophyll • Holozoic mode of nutrition • Reserve food in the form of glycogen or Plus 1 Biology A virus is a nucleoprotein. It consist of a • Genetic material - The genetic material is either RNA orDNA. • Bacteriophages - Viruses which infect the bacteria are called bacteriophages. They have double stranded DNA as genetic ma- Winner’s Coaching Centre Biological Classification Practice makes progress • 265 . terial. Diseases caused by viruses Viruses cause diseases like mumps, small pox, herpes,Influenza and AIDS. Viroid - In 1971 T.O. Diener discovered a new infectious agent that was smaller than viruses and caused Potato spindle tuber disease. It was found to be a free RNA without surrounded by any nucleoprotein coat. • Lichens-Lichens are symbotic association betweenalgae and fungi. The fungal component is known as mycobiont and the algal component is known as phycobiont. • Phycobiont synthesise organic food by IMPORTANT QUESTIONS 1. photosynthesis,fix nitrogen etc. Dinoflagellates are mostly (a) Marine saprophytic • Mycobiont protects the alga, absorb water and minerals for lichen. (b) Fresh water and saprophytic • Prions : In modern medicine certain in- (c) Marine and photosynthetic fectious neurological diseases were (d) Terrestrial and photosynthetic found to be transmitted by an agent consisting of abnormally folded protein. 2. The agent was similar in size to viruses. Fill in the blanks. 1) Rhizopus : most notable diseases caused by prions are Yeast —————— bovine 2) Hold fast These agents were called prions. The spongiform encephalopathy (BSE) commonly called mad cow disease : : Phycomycetes Anchorage Heterocyst : —————— in cattle. 3. Find out the odd one: Diatom, Gonyaulax, Yeast, Euglena, Plasmodium Plus 1 Biology Winner’s Coaching Centre Biological Classification your parents, who will never let you down • 266 . 4. 5. 1) Vibrio : comma shaped (a) Viral diseases ———— : Rod shaped (b) bacterial diseases 2) Agaricus : Basidiomycetes (c) Protozoan diseases Penicillium : ———— (d) fungal diseases Name the following : 10. virus is 1. A protist which can live both as an autograph and as heterotroph. (a) Prion 2. Name a protist group which consists (c) bacteria (d) mycoplasma of saprophytes. 6. 8. Which of the following phenomena ble indicator of SO2 pollution in the en proves that viruses are living? vironment (a) They carry on metabolic activity (a) Lichens (b) They carry anaerobic respiration (c) Algae 12. (b) Conifers (d) Fungi Pick up the wrong statement. (d) They cause infection a) Cell wall is absent in Animalia. Tobacco mosaic virus is b) Protista have photosynthetic and (a) spherical (b) rod shaped (c) cuboidal (d) oral heterophic modes of nutrition. Viruses are also known as c) Some fungi are edible d) Nuclear membrane is present in Monera. (a) nucleoprotein particles 9. (b) viroids 11. Which of the following is the most suita (c) They multiply in host cells 7. An infectious agent that is smaller than 13. Which one of the following statements is (b) virion wrong? (c) Protozoan diseases a) Golden algae are also called desmids. (d) core b) Eubacteria are also called False ba– cteria In plants, mosaic formation, leaf rolling and curling, yellowing and vein clearing, c) Phycomycetes are also called algal are the symptoms of fungi. Plus 1 Biology Winner’s Coaching Centre Biological Classification Hard work beats talent when talent doesn't work • 267 . d) Cyanobacteria are also called called 20. blue green algae. 14. tensively in biochemical and genetic work? Citrus canker is a (a) Viral disease (b) Bacterial disease (c) fungal disease (d) Protozoan disease 15. The free living thalloid body of the slime mould is known as (a) Protonema Which of the following fungi is used ex- 21. (a) (b) plasmodium (a) Neurospora (b) Mucor (c) Rhizopus (d) Aspergillus Match them Properly Chryso- 1. Parame- phytes cium (b) Dinoflagel- 2. Saprophyt- (c) Euglenoids 3. Euglena (d) Slime Gonyaulax (c) fruiting body (d) Mycelium 16. Trypanosoma causes (a) sleeping sickness (c) malaria (b) Cholera (d) food poisoning 4. moulds (e) Protozoans 5. Diatoms and golden algae 17. Among rust, smut and mushroom, all the 22.Match the column Properly three (a) are pathogens (b) are saprobes (a) Coccus 1. shaped (c) bear ascocarps (d) bear basidiocarps 18. Insectivorous plants are principally Rod (b) Bacillus 2. Spherical (c) Vibrio 3. Spiral (a) Autotrophs (b) Partially heterotrophic shaped (c) Parasite (d) Spirillum 4. shaped (d) pathogenic 19. Comma All the given belong to Deuteromycetes, except (a) agaricus (b) Cercospora (c) Ticoderma Plus 1 Biology (d) pyricularia 23. What is capsid? What is its function? 24. What are Prions? 25. What is called Alternation of Genera- Winner’s Coaching Centre Biological Classification Value yourself to fight for happiness • 268 . tions? 26. Why iv. Deuteromycetes are called class (a) (ii) and (iii) imperfect fungi? (b) (i) and (iv) PREVIOUS YEARS QUESTIONS 27. Algal component of lichen is phycobint. (c) (i) and (iii) Observe the figure given below. Name the organism. (d) (ii) and (iv) 31. The name ‘Virus’ that means venom or poisonous fluid was given by 32. (a) Pasteur (b) Ivanowsky (c) Beijerinck (d) Stanley The class of fungi known as imperfect fungi is——— (a) Ascomycetes 28. (b) Phycomycetes Observe the relationship between the first two terms and fill in the blank. (a) Mushroom : Agaricus (d) Basidimycetes (b) Bread mould : ———— 29. (c) Deuteromycetes 33. Fill in the blank: ble to cyanobacteria. In Anabaena specialized cells called — a) Important decomposers b) Form blooms in polluted water c) Presence of prominent nucleus d) Completely lack of a cell wall —— help in nitrogen fixation. 30. Read the following statements and select the correct statements from the given choices: i. Identify the statement which is applica Methanogens are present in the guts of Observe the relationship between the first pair and fill up the blanks using ap ruminant animals. ii. Mycoplasma has distinct cell wall. iii. Viroids are infectious naked DNA molecules. 34. propriate terms. (a) Carolus Linnaeus—Two kingdom classification R.H. Whittaker - ————— Plus 1 Biology Winner’s Coaching Centre Biological Classification Think like a proton, always positive • 269 . 35. (b) Thermoacidophiles - Extreme heat (a) What is symbiosis? Halophiles - ———— (b) State the economic importance of Lichens. Diatoms, the chief producers in the oceans, are useful to us even after their 40. death. Evaluate the statement. 36. Five kingdom arrangement of organisms was given by R.H. Whittaker, State the criteria followed by Whittaker for his Fill up the second part by observing the classification. relationship of the first part. 41. (a) Monera - Prokaryote Slime moulds grow in damp places. (a) Name the vegetative part of thallus. Protista - ———— (b) Give an example of slime mould. (b) Bacteria live in extreme salty areas - ANSWERS Halophiiles Bacteria live in marshy areas - —— 1. c) Marine and photosynthetic 2. 1) Ascomycetes 3. Yeast 4. 1) Bacillus 2) Ascomycetes Halophiles 5. 1) Euglena 2) Slime mould Archaebacteria growing in hotsprings - 6. c) They multiply in host cells. 7. b) Rod shaped 8. a) Nucleoprotein particles 9. a) Viral diseases plants- ——— 10. b) Viroids Ramu decided to construct a biogas plant 11. a) Lichens in his home due to the recent hike in the 12. d) Nuclear membrane is present in mon- 37. Observe the relationship between the words of the first sentence and fill the second one. (a) Archaebacteria growing in salty areas— —— (b) Association of fungus with algae - Lichens Association of fungus with roots of 38. cost of cooking gas. Name the group of bacteria involved in this process. 39. era. 13. Lichens are symbiotic association of Al gae and Fungi. Plus 1 Biology 2) N2 fixation b) Eubacteria are also called false bacteria. 14. b) Bacterial disease Winner’s Coaching Centre Biological Classification Today a reader, Tomorrow a leader • 270 . 15. b) Plasmodium 16. a) Sleeping sickness 17. d) Bear basidiocarps 18. b) Partially heterotrophic 19. a) agaricus 20. a) Neurospora called capsomeres. The capsid protects the nucleic acid. The capsomeres are arranged helical or polyhedral geometric forms. 24. They are abnormally folded proteins that cause some infectious neurological disease. These are similar in size to viruses. This causes bovine spongiform encepha- lopathy [BSE] or mad cow disease in 21. cattle. Its analogous variant causes Cr (a) Chryso- 5. phytes Diatoms Jacob (CJD) disease in humans. and golden 25. algae (b) Dinoflagel- 4. The life cycle of plants has two distinct phases – the diploid sporophytic and the Gonyaulax lates haploid haploid gametophytic phase. (c) Euglenoids 3. Euglena These phases alternate with each other. (d) Slime Saprophyt- The lengths of the haploid and diploid moulds ic protists phases vary among different groups of Protozoans 1. Parame- plants. This phenomenon is called Alter- (e) 2. cium nation of Generation. 22. 26. They are usually known as imperfect fungi because only the asexual or vegeta- (a) Coccus 2. Spherical tive phase of them is known. A large number of deuteromycetes are decom- (b) (c) (d) Bacillus Vibrio Spirillum 1. 4. 3. Rod posers, while some members are para- shaped sites. Comma 27. Euglena shaped 28. Rhizopus Spiral 29. Heterocyst 30. (i) and (iv) 31. Ivanowsky 32. Deuteromycetes shaped 23. The protein coat on the virus is called capsid. It is made up of small sub units Plus 1 Biology Winner’s Coaching Centre Biological Classification Today a reader, Tomorrow a leader • 271 . 33. Form blooms in polluted water 34. (a) five kingdom classification (b) Extreme salt 35. Diatomaceous earth used in polishing, filtration of oils and syrups. 36. (a) Eukaryote (b) Methanogens 37. (a) Thermoacidophiles (b) Mycorrhiza 38. Methanogens 39. (a) Close and prolonged interaction be tween organisms of different species. (b) Litmus is obtained from a lichen, Ro cella montaignei. Lichen is used in the preparation of usnic acid. 40 (1) Complexity of structure of cell (2) Complexity of the body of organisa tion (3) Mode of nutrition. 41. (a) Plasmodium (b) Physarum Plus 1 Biology Winner’s Coaching Centre Biological Classification Nothing can stop you now • 272 . CHAPTER-3 PLANT KINGDOM affected by environment. Plant kingdom includes all the pho- tosynthetic producers of biosphere, Fungi and members of Monera and Protista having cell walls have now been excluded from plantae. 2. Natural system of classification In this system of classification not only the external features, but also internal features like ultrastructure, anatomy, 1. Artificial system of classification • based on one or a few superficial characters. • • and Joseph Dalton Hooker. The artificial system of classification is 3. Phylogenetic system of classification This system of classification uses only su- In this system of classification, organisms are perficial morphogical characters such as classified on the habit, colour, numberand shape of leaves quence and genetic relationships among the etc. organisms. This classification is based mainly on the vegetative characters or on the androccium structure (system given by Linnaeus). basis of evolutionary se- Eg: Engler and Prantl's classification. Numerical Taxonomy • Drawbacks of artificial system of classifica- Taxonomy based on statistical methods is called numerical taxonomy. tion • i) This method utilizes calculating ma- This system separated closely related chines and computers for the evaluation species. of similarities and differences between the different species of organisms. ii) Artificial system gave equal weightage to vegetative and sexual characteristics. This is not acceptable since we know that vegetative characters are more easily Plus 1 Biology Cytotaxonomy • Taxonomy of organisms by the use of their cytological characters is called cyto cytotaxonomy. Winner’s Coaching Centre Plant Kingdom There is no substitute for hard work • 273 . • The cytological features like chromo- (Chlamydomonas) or non flagellated some number,structure and behaviour (Chlorella), colonial form (Volvox) or of chromosomes are used for classifica- multicellular filamentous (Ulothrix and tion. Spirogyra). Some are flattened and leaf like (Laminaria). Chemotaxonomy. • • 5. It uses the chemical constituents of the forms. The attached forms fix the plant plants in classification. body with the help of anchoring structure The sequencing of DNA and chemical called holdfast. nature of proteins are commonly used to 6. study similarities of species. • They reproduce by vegetative, asexual and sexual methods. Calcium oxalate crystals (raphides) are 7. commonly found in 35 families of plants. Vegetatvie reproduction takes place by fragmentation.Eg: Sargassum. 8. Asexual reproduction is by the production of different types of spores like zoo- ALGAE spores.Zoospores are flagellated(motile) Algae (singular-alga) are chlorophyll bearing simple thalloid, the study of and on germination produces new plants. 9. Sexual reproduction takesplace by the fusion of two algae is called phycology. size (eg: Chlamydomonas) or non flagellated (non Salient features of algae 1. Algae may be free-floating or attached - motile) but similar in size (eg: Spirogyra). Such reproductions called isoga- Algae are chlorophyll bearing, auto- mous. trophic organisms. Fusion of 2. size habitat. is two gametes dissimilar in termed anisogamous. (Eg.. Some species of Chlamydomonas) 3. 4. They occur in moist stones, soils and wood. Some of them also occur in asso- Fusion between one large, non motile female ciation with fungi (lichen) and animals gamete and a smaller motile male gamete is (eg: on sloth bear) called oogamous (eg:Volvox, Fucus), The thallus is unicellular flagellated Economic importance of algae Plus 1 Biology Winner’s Coaching Centre Plant Kingdom Whatever you are, be a good one • 274 . 1. At least half of the total CO2 fixation on earth is carried out by algae through photosynthesis. The increases the level of dissolved oxygen (DO) in the immediate phyceae. 1. Chlorophyceae (green algae) I. Algae are primary producers of energy II. the food cycles of all aquatic animals. They bear pigments- III. The chloroplasts may be discoid, plate Many species of Laminaria, Porphyra like, reticulate,cup-shaped spiral or rib- and Sargassum are used as food. bon shaped in different species Certain large marine amounts algae produce IV. (large brown algae) containting protein besides starch. V. Eg: (i) Algin from brown algae like kelps They have storage bodies called pyrenoids of hydrocolloids (water holding substances). Cell wall made up of cellulose. VI. Vegetative reproduction by fragmentation or by theformation of different types (ii) Carrageen is obtained from red algae. of spores. VII. Asexual 3. dominant chlorophyll a and b in chloroplasts. rich compounds which form the basis of 3. unicellu- lar, colonial or filamentous. environment, 2. The plant body may be reproduction is by Agar is a gel like substance obtained flagellated zoospores produced in zoo- from sporangia. red algae like Gelidium and Gracilaria VIII. Sexual reproduction occurs by the formation of sex cellsand it may be isoga- Agar is used as a culture medium for bac- mous,anisogamous or oogamous. Ex- teria, fungi and other microbes. Agar is ample: also used in the preparation of icecreams Ulothrix, Spirogyra and Chara, Chlamydomonas, Volvox, and jellies. Chlorella and Spirullina are unicellular algae rich in proteins, used as food supplements even by space travellers. Algae are divided into three main classes. Chlorophyceae, Phaeophyceae and RhodoPlus 1 Biology Winner’s Coaching Centre Plant Kingdom Education is the key to success • 275 . phylls. The colour of the thallus vary from olive green to various shades of brown depending upon the amount of xanthophylls pigment fucoxanthin. IV. Food is stored as complex carbohydrates, which may be in the form of laminarin or mannitol. V. on outside by a gelatinous coating of algin. VI. The protoplast contains a centrally located vacuole and nucleus. VII. The plant body is usually attached to the substratum by a holdfast. The stalk of the algae is called stipe and the leaf like photosynthetic organ is called frond. VIII. Vegetative reproduction takes place by fragmentation. pear shaped and have two unequal flagella. IX. Sexual reproduction is isogamous, anisogamous or oogamous. Fusion of gam- 2. Phaeophyceae (Brown algae) etes may take place in water or in the oogonium (in oogamous species). The I. They are found in marine habitat. II. They are multicelluar. Some are simple gamete are pyriform (pear-shaped) and bear two laterally placed flagella. branched filamentous forms (eg: Ecto- Eg: Ectocarpus, Dictyota, Laminaria, carpus).Largest sea brown algae are Sargassum, Fucus. called sea weeds or sea kelps having a length of100 metres. III. Photosynthetic pigments include chloro- 4. Rhodophyceae (Red algae) phyll a, c, carotenoids and xanthoPlus 1 Biology Winner’s Coaching Centre Plant Kingdom There is no substitute for hard work • 276 . I. Majority of red algae are marine. II. They are red due to the presence of red 3) um. They produce biflagellate antherozoids. pigment, r- phycoerythrin. 4) They occur in warmer areas. They are I. The female sex organ is called archegonium. It is flask shaped and produces sin- found in well lighted areas close to the gle egg. surface of water and also at great depths in oceans, where little light penetrates. The male sex organ is called antheridi- 5) The antherozoids are released into water where they come in contact with the ar- II. The thallus is multicellular. III. The food is stored as floriedean starch. IV. Vegetative reproduction is by frag- chegonium. Thus water is essential for fertilisation. 6) duce the zygote. mentation. Asexual reproduction by non-motile spores. Sexual reproduc- Antherozoid fuses with the egg to pro- 7) The zygote develops into a multicellular tion by non motile gametes. Sexual re- body called sporophyte. The sporophyte production is oogamous. is not free living but attached to the photo- Example: Gracilaria, synthetic gametophyte and derives nour- Polysiphonia, ishment from it. Porphyra and Gelidium. BRYOPHYTES The plants can live in soil but are dependent 8) The sporophyte undergoes reduction division (meiosis) to produce haploid on water forsexual reproduction, bryophytes spores. The spores germinate toproduce are known as "amphibians of plant king- gametophyte dom" They occur in damp humid and shaded localities. 1. Characteristics of bryophytes 1) Economic Importance of Bryophytes birds and other animals. The plant body is thallus like and prostrate or erect. It is attached to the sub- 2. zoids. They lack true roots, stem or Mosses bind soil and hence prevent soil erosion. stratum by unicellular or multicellular rhi- 2) Some mosses provide food for mammals, 3. The Moss Sphagnum is used by garden- leaves, but they may possess root like, ers to keep cut plant parts moist during leaf like or stem like structures. transportation. Sphangnum provide peat that have long been used as fuel. The plant body is a gametophyte ie, can produce gametes. Plus 1 Biology 4. Mosses along with lichens are the first Winner’s Coaching Centre Plant Kingdom Always have an attitude of gratitude • 277 . organisms to colonise rocks and hence are of great ecological importance. They decompose rocks making the with the egg nucleus. • sisting of foot, seta, capsule arises from substrate suitable for the growth of high- the fertilised egg of the archegonium. er plants. Bryophytes are divided into liverworts and • • The plant body is a green, flat and dorsiven- • of unicellular hair like structures called rhizoids. of liverworts: - Riccia, (ii) Mosses i) They are found growing in moist places. Asexual reproduction takes place by frage- ii) The plant body is a gametophyte. The mentation of thalli,or by the formation of specialised structures called gemmae (gemma). gametophyte occurs in two forms. (i) creeping, green, branched and filamen buds, which develop in small receptacles in tous stage. the thallus called gemma cups. The gemmae are detached from the parent body and germinate to form new individuals. Protonema stage. It is formed from the germination of spore. Photonema is a Gemmae are green, multicellular, asexual (ii) Leafy stage. It develops from secondary protonema as a lateral bud. It consists of slender erect axis bearing spirally arranged The male reproductive branches called leaves. Basal portion bears numerous multi- antheridiophore.Female branch is called cellular branched rhizoids. archegoniophores. Reproduction Antheridia produce flagellated sperms (antherozoid). Vegetative reproduction in mosses is by Archegonia produce female gametes (egg cell) • Examples Marchantia tral thallus. It is attached to the soil by means • The spores germinate to form free living gametophytes. (i) Liverworts • The spores are formed in the capsule after meiosis which are dispersed by wind. mosses. • After fertilisation a tiny sporophyte con- fragmentation and budding in the secondary protonema Antherozoids swim in water and fuses Plus 1 Biology Winner’s Coaching Centre Plant Kingdom Be the light for your family • 278 . Sexual reproduction: the fertile leaves called sporophylls. In some cases sporophylls may form dis1. Antheridium is an orange colored club- tinct compact structures called strobili or shaped structure. It produces the flagel- cones. Eg: Selagenella, Equisetum. lated sperms (antherozoids) Female 2. branches produce flask shaped female iv) The sporangia produce spores. The spores reproductive organs called archegonia. are produced by meiosis of spore mother Archegonium produces the egg. cells. The spores are uninucleate and hap- v) reach the egg cell. 3. loid. The antherozoids swim in water to shaped photosynthetic structure called After fertilisation the zygote develops prothallus. The prothallus is the haploid into a sporophyte. The sporophyte is gametophyte. differentiated into foot, seta and capsule. 4. The spores are formed in the capsule af- vi) The gametophyte organ ter meiosis.The spores are dispersed by bears male sex called antheridia and female sex organ called archegonia. wind. Spores germinate pro- The spores germinate to form a thin heart vii) Antheridia produce antherozoids. Archegonia produce oosphere (egg cell). tonema. Example:-Funaria, Polytrichum and viii) Water is essential for fertilisation. Fu- Sphagnum. sion of male gamete with the egg present in the archegonium results in the formation of zygote. PTERIDOPHYTES The pteridophytes include horse tails ix) Zygote produces multicellular well differentiated sporophyte which is the domi- (Equisetum) and ferns. nant phase of pteridophytes. General characteristics i) x) These are seedless vascular plants. ii) Plant body is a sporophyte which is differentiated into true roots, stem and jority of pteridophytes all the spores are of similar types. Such plants are called homosporous. Heterosporous Pteridophytes leaves. iii) The sporangia arise on the lower side of Plus 1 Biology The sporophyte produces spores. In ma- Genera like Selagenella and Salvinia which Winner’s Coaching Centre Plant Kingdom Be giving, enjoy sharing • 279 . produce two kinds of spores-megaspores v) In Cycas the leaves are persistant for a (large) and microspores (small) are known as few years. The leaves of gymnosperms heterosporous. are to withstand extreme temperature, humidity and wind. The The megaspore germinate to form female ga- needle like leaves of conifers reduce the metophyte. The microspore germinate to form surface area. The thick cuticle and sunk- male gametophyte. The pteridophytes adapted en stomata also help to reduce water are classified into following four classes loss. vi) They are vascular plants with xylem i) Psilopsida (Eg. Psilotum) and phloem tissue. Xylem lacks vessels ii) Lycopsida (Eg. Selagenella, Lycopodi and phloem lacks companion cells. um) vii) They are seed bearing flowerless plants. i) Sphenopsida (Eg.Equisetum) ii) Pteropsida (Eg.Pteris,Adiantum) GYMNOSPERMS viii) The plant body is a diploid sporophyte (2n). Reproduction The gymnosperms are seed bearing vascular plants without flower. They are naked seed- Gymnosperms are heterosporous ie.. bear two ed plants. different types of spores such as microspores (male) and megaspores (female). The micro- General Characters spores develop in microsporangia. The mega- i) spores develop in Gymnosperms are naked seeded plants. like structures ii) iii) The plant body is differentiated into called sporophylls. The sporophylls are roots, stem and leaves. two types megasporophylls and microsporo- The root is a taproot system and is well phylls developed. Roots in some genera have The reproductive structures are called lax fungal association in the form of or cones or strobili. small specialised roots called coralloid roots are associated N2, fixing The stems are branched or un branched. Plus 1 Biology The male cone consists of microsporophylls and female cone consists of megasporophylls Microsporophylls cyanobacteria. iv) of (pollen bear microsporangia sac)which contains pollen grains (microspores). Winner’s Coaching Centre Plant Kingdom Make time for yourself • 280 . Megasporophylls bear megasporangia 7. Which one is responsible for the for- (ovules). In the megasporangium the mega- mation of peat? spore mother cell is differentiated from one of a) Riccia b) Sphagnum bryo and the ovule develops into seeds. c) Marchantia IMPORTANT QUESTIONS d) Funaria the cells of the nucellus. After fertilization zygote develops into em- 8. 1. A colonial algae is ——— 2. Agar - agar is commercially obtained from —— 3. 4. Rhodophyceae is called red algae be10. b) Funaria c) Marchantia d) Fucus Isogamous condition with non- flagellated gametes is found in Antheridium : Male sex organ —————-: Female sex organ Which of the following is a liverwort? a) Sphagnum 5. Rhodophyceae : 9. cause of the pigment—— Chlorophyceae : Green algae A plant that has seeds but no flowers and fruits 11. The cell wall of spirogyra contains ——- 12. ——————: Naked seeded plants 13. Pinus : Mycorrhizal roots Cycas : ——- a) Chlamydomonas 14. Analyse the table and fill in the blanks. b) Spirogyra Algal class Pigment Stored food d) Fucus 1. Phaeophycean Fucoxanthin (1) In gymnosperms, the development of 2. Chlorophyceae (2) Starch Rhodophyceae (3) (4) c) Volvox 6. pollen grains occurs in a) Strobili b) Microsporangia c) Megasporangia d) Macrosporangia Plus 1 Biology PREVIOUS YEARS QUESTIONS 15. The given figure shows a plant belonging to liverworts. Identify the plant. Name Winner’s Coaching Centre Plant Kingdom Dedication is expensive than talent • 281 . the asexual buds seen on it and write their features. Chlorophyll a, b Phaeophyceae Chlorophyall Laminarian a, c and (b) and Mannitol (c) 20. (a) Chlorophyceae Chlorophyll a, d and phycoerythrin (d) Amphibians of plant kingdom is used do denote a specific group in plant kingdom Name the plant group and list any three vegetative or reproductive characters of that plant group. 21. on aquatic ecosystems, man is benefited 16. Match Column A and Column B A 1) Prothallus 2) Protonema Even though algae are primary producers by algae in a variety of ways. Write any four points in favour of this statement. B i) Asexual buds in liverworts 22. Write the name of the stored food of the algal class in the table given below: ii) Sporophyte of Angiosperms Class Stored food 3) Antheridium iii) Thalloid gametophyte of pteridophytes 4) Gemmae iv) Male sex organ in bryotes v) Gameophytic stage of 1) Phaeophyceae 2) Rhodophyceae 17. Algae are useful to man in a variety of ways. Suggest any four uses off algae. 18. Write any two distinguishing features of the algal class Rhodophyceae. 19. 23. Distinguish between protonema and pro thallus 24. Match the columns A and B: Complete the given table of algal divi sions and their main characteristics by filling (a), (b), (c) and (d). Plus 1 Biology Winner’s Coaching Centre Plant Kingdom Performance comes from practice • 282 . A B (i) Prothallus a) Identify two heterosporous genera. b) “Heterosporty is a precursor to seed habit”. Point out any one (a) Mosses common character found in heter (ii) Sporophyte (b) Plant body of algae (iii) Coralloid roots (c) Gametophyte of pteridophytes (iv) Protonema (d) Sporangia bearing leaves ospory and seed habit. ANSWERS 1. Volvox 2. Gracilaria and Gelidium 3. Phycoerythrin 4. c) Marchantia genera like selaginella and salvinia show 5. b) Spirogyra a unique feature in spore formation. 6. b) Microsporangia a. 7. b) Sphagnum 8. Rhodophyceae : Red algae 9. Archegonium 10. Gymnosperms 11. Cellulose 12. Gymnosperms (e) Nitrogen fixa25. Unlike a majority of the pteridophytes, What is this feature? b.Briefly comment on its signifi cance. 26. Match the Column A with B A B a) Floridena starch Gymno- b) Double fertiliza- Red algae 13. Coralloid roots c) Coralloid roots Fern 14. 1) Mannitol and Laminarin d) Prothallus Angisperm 2) Chlorophyll a 3) Phycoerythrin 27. Give reasons for the following: 4) Floridean starch a) Bryophytes are called amphibians of 15. plant kingdom. 28. Marchantia, Gemma cup Most pteridophytes are homosporous but Features : Gemmae are green multicellu there are exceptions. lar, asexual buds which develop into small receptacles. Gemmae become de Plus 1 Biology Winner’s Coaching Centre Plant Kingdom Practice makes progress • 283 . tached from the parent body and germi nate to form new individuals. 16. A 17. Starch (a) Phaeophyceae Chlorophyall Laminarian a, c and (b) and Mannitol fucoxanthin v) Gametophytic stage of mosses Rhodophyceae (c) Chlorophyll a, d and phycoerythrin Floridean starch (d) 20. Bryophytes 3) Antheridi- iv) Male sex organ in Vegetative characters 4) Gemmae 1. Thallus is prostrate or erect. 2. They lack true roots, stem or i) Asexual buds in liverworts 1. During photosynthesis algae fix CO2 and liberate O2 2. 3. Certain marine algae are used as Presence of unicellular or multicell lular roots. Reproductive characters Marine brown and red algae pro duce hydrocolloids. E.g., Algin 4. leaves. 3. food They are primary producers in an The main plant body of the Bryo 2. The male sex organ is multicellular antheridium. Flagella are not present in gamete and spores. 3. The female sex organ called Ar chegonium Red pigment phycoerythrin is present. 19. 1. phyte is haploid aquatic ecosystem. 18. Chlorophyll a, b B 1) Prothallus iii) Thalloid gametophyte of pteridophytes 2) Protonema Chlorophyceae 21. 1. Chlorella and Spirulina are rich in protein. 2. Agar—agar is obtained from Gracilaria and Geledium 3. Used for the preparation of ice— creams and jellies. 4. Plus 1 Biology Winner’s Coaching Centre Used for the growth of microbes. Plant Kingdom Nothing can stop you now • 284 . 22 . 1) Laminarian, Mannitol 23. A B 2) Floridean starch a) Floridena starch Red algae Protonema: It is a creeping, green, fila- b) Double fertiliza- Angiosperm directly from a spore of mosses. c) Coralloid roots Gymno- Prothallus: Heart shaped, photosynthet d) Prothallus Fern mentous, branched structure develops ic gametophyte of pteridophytes. 27. They depend on water for sexual reproduc- 24. tion. A B (i) Prothallus 28. a) (c) Gametophyte of pteridophytea (ii) Sporophyte (d) Sporangia bearing leaves (iii) Coralloid roots (e) Nitrogen fixation (iv) Protonema (a) Mosses 25. a) Selaginella and salvinia b) Female gametophyte is retained on the parent sporophyte. Heterospory b) (1) The mega spores and micro spores germinate and then give rise to male and female gametophytes. c) (2) The development of zygote into young embryo occurs within female gametophyte. 26. Plus 1 Biology Winner’s Coaching Centre Plant Kingdom Be the helping hand of knowledge to your friend • 285 . CHAPTER - 4 ANIMAL KINGDOM BASIS OF CLASSIFICATION The individuals belonging to the animal kingdom differ in their structure and form. equal halves through any - plane, it is called asymmetry. Eg: some sponges. 2. But some fundamental features are common to various individuals in relation to the Radial symmetry If an animal which can be cut into two equal halves through any of the radial planes, it is- 1. Arrangement of cells called radial symmetry 2. Level of body organization 3. Body symmetry 4. Nature of coelom. 5. Patterns of digestive, circulatory or reproductive systems. These fundamental fea- tures are used as the basis of animal classification. 1. Levels of organisation 1. Cellular level of organisation (aoomeler) 2. Tissue level of organization 3. Organ level of organization Eg: Coelenterates, ctenophores and echino- 4. Organ system level of organization. derms . 3. Bilateral symmetry II. Symmetry If an animal which can be cut into two equal The arrangement of body parts on the sides of halves through a single plane along the longi- the main median axis of a body is called Sym- tudinal axis, it is called bilateral symmetry. metry. It is of three types - asymmetry, radial symmetry and bilateral symmetry . 1. Asymmetry If an animal which cannot be cut into two Plus 1 Biology Winner’s Coaching Centre Animal kingdom Time and tides wait for none • 286 . IV. Coelom (body cavity) Eg: Annelids, man etc. III. Diploblastic and triploblastic organisation (i) Diploblastic animals: • the body wall and the digestive tract of animals is called the coelom. Animals which are developed from the two—layered (germ layers) embryo, are called diploblastic animals. • The coelom is lined by the mesoderm On the basis of the nature of coelom, animals are divided into 3 groups. The outer layer of the embryo is called ecoderm, the inner layer is called endo 1. Animals having no coe- helminthes (flatworms). lar layer is seen in between the ectoderm and endoderm. It is called Mesoglea, Acoelomates: lom are called acoelomates. Eg: Platy- derm . An undifferentiated non— cellu 2. Pseudocoelomate: In some animals, the body cavity is not lined by mesoderm, Eg: Coelenterates and Sponges. (ii) The fluid—filled body cavity in between instead, the mesoderm is present as scat Triploblastic animals: Animals which tered pouches in between the ectoderm are developed from the three layered em- and endoderm. Such a body cavity is bryo, are called triploblastic animals, called pseudocoelom. Eg: Platyhelminthes to Chordates. 3. Coelomates: Animals having true coe- The 3 germ layers of the embryo are the lom are called coelomates or eucoelo- ecoderm, mesoderm, and endoderm. mates. Eg: annelids, molluscs, arthropods, echinoderms, hemichordates, and chordates Plus 1 Biology Winner’s Coaching Centre Animal kingdom Work hard to show the best in you • 287 . Chordates: Animals with notochord eg: fishes, birds, mammals, etc. Non - chordates: Animals without notochord eg: Porifera to echnioderms. CLASSIFICATION OF ANIMALS Based on common fundamental features, the kingdom Animalia is broadly classified into 11 phyla—Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata. 1. PHYLUM PORIFERA (Sponges) (pore—bearing animal) I. V. Segmaentation They are asymmetrical, multicellular, diploblastic with cellular level of organisation. In some animals, the body is externally and internally divided into segments with a serial reptition of at least some organs. For example, in earthworm the body shows this II. They are generally marine. III. They are pore—bearing animals and their body is perforated by numerous pattern called metameric segmentation and openings or pores called ostia. the phenomenon is known as metamer IV. ism. They have a Water transport system (water canal system). VI. Notochord In some animals, a mesodermally derived V. Water enters through ostia into a cen- tral cavity called spongocoel. rod—like structure is called notochord. Water from spongocoel goes out through os- The notochord is a stiff and flexible rod of tis- culum. sue running along the dorsal side below the transport is helpful in food gathering, nerve cord and above the alimentary canal . respiratory exchange and removal of waste. Based on the presence or absence of notochord, animals are classified into 2 groups Chordates and non - chordates. Plus 1 Biology This pathway of water VI. Choanocytes or collar cells line the spon gocoel and the canals. Winner’s Coaching Centre Animal kingdom Make your knowledge useful for others • 288 . VII. Digestion is intracellular. 2. (Phylum Cnidaria) VIII. Sponges have an endoskeleton formed 1. of spicules and Spongin fibres. IX. Asexual reproduction takes place by rical animals. 2. Sponges are hermaphrodite (sexes are 3. In coelenterates, certain ectodermal cells are modified into stinging cells or cnido- not separate).Eggs and sperms are pro blasts or cnidocytes, hence the name duced by the same individual. Cnidaria XII. Fertilisation is internal and the devel opment of larva is indirect. 4. Each cnidoblast possesses a stinging capsule called nematocyst containing poi- Examples: Spongilla (fresh water spong They show tissue level organisation and are diploblastic. fragmentation and budding. XI. They are aquatic (mostly marine), sessile or free swimming radially symmet- Sponges reproduce asexually and sex ually X. PHYLUM COELENTERATA sonous fluid. The cnidoblasts are defen- es), Sycon (Scypha), Eu- sive cells used to kill or paralyse other spongia (bathsponge ). prey and enemies. The cnidoblasts are mainly found on the tentacles. 5. They have a central internal cavity called gastro vascular cavity coelenteron. It opens out by a single opening called mouth on hypostome. Anus is absent. 6. The coelenterates are holozic and carnivorous in nutrition. Digestion is intracellular and extracellular. Plus 1 Biology Winner’s Coaching Centre Animal kingdom Learn Grow and Be happy • 289 . 7. Coelenterates have 2 types of basic body 1. jellies. forms polyp and medusa. Polyp They are known as sea walnuts or comb :- is the sessile tubular (cylindrical 2. They are exclusively marine, radially attached form, with upwardly directed mouth symmetrical, diploblastic organism and tenacles. It Presents theasexual stage. . acoelomates Eg: Hydra and Adamsia. 3. They show tissue level of organisation. Medusa: - is the umbrella—like, free— 4. Animal body bears 8 external rows of swimming form, with downwardly directed cilia. Cilia in each row together to form mouth and tentacles. It represents the sexual Comb plates which help in locomotion. stage. Medusa can be regarded as an upside— 5. down polyp with reduced stalk and capable of Digestion is both extracellular and intracellular. swimming way. 6. Eg: Aurelia (opeilo, jelly fish). organism to emit light ) is well marked. Coelenterates exhibit alternation of generation (metagenesis) in their life cycle. Bioluminescence (the property of living 7. They reproduce Sexually only. 8. They are hermaphrodites (male and female sex organs are seen in one animal.) 9. Fertilisation is external with indirect development. 10. The zygote develops into a larvae which grows into an adult. Examples: Pleurobrachia (sea gooseberry),and Ctenoplana. PHYLUM CTENOPHORA (Sea walnuts or comb jellies) Plus 1 Biology Winner’s Coaching Centre Animal kingdom Revise to make it perfect • 290 . 4. PHYLUM PLATYHELMINTHES (flat worms) 4. PHYLUM - ASCHELMINTHES 1. (round worms) They have dorso - ventrally flattened body, hence are called flatworms. 2. These are mostly endoparasites found in animals including human beings 3. They are bilaterally symmetrical triporgan level of organisation. Hooks and suckers are present in the 3. 4. Some of them absorb nutrients from face. Shows bilateral symmetry, triplo- They show developed muscular plete . 5. They are dioecious, ie. Male and female s are different ; Specialised cells called flame cells help in osmoregulation and excretion. 7. Sexes are not separate. 8. Fertilisation is internal and development is through many larval stages. 9. parasitic in plants pharaynx and alimentary canal is com- the host directly through their body sur- 6. They are freeliving, aquatic, terrestrial or blastic pseudocoelomate animal. parasitic forms. 5. They show organ - system level of body organisation. 2. loblastic and acoelomate animals with 4. 1. Some members like Planaria possess high regeneration capacity. 6. The male is smaller than the female. 7. Fertilisation is internal. 8. Excretion is done through excretory pore. E.g. : Ascaris (round worm), Wauchere ria (filariaworm) and Ancylostoma (hookworm). Example: Taenia (Tapeworm), Fasciola (Liver fluke). Plus 1 Biology Winner’s Coaching Centre Animal kingdom Success means self-satisfaction • 291 . leech). 6. PHYLUM ANNELIDA (Segmented worms) 1. Annelids are terrestrial (eg. Earth worms) or marine (eg: Neries) or fresh water (eg: Nais) or parasitic (eg: leeches). 2. They possess an organ - system level of body organisation. 3. Annelids are bilaterally symmetrical , triploblastic and coelomate. 4. They are metamerically segmented. Body is externally (body surface) divided 5. into segments called metameres. Hence, 7. the phylum name annelida. Arthropods are animals with jointed legs and appendages They possess longitudinal and circular PHYLUM ARTHROPODA 1. This is the largest phylum of Animalia. 2. They have organ –system level of organization. 3. They are bilaterally symmetrical, triploblastic, segmented and coelomate animals. which help in locomotion. 4. The body is covered by Chitinous exoskeleton. 7. Circulatory system is of closed type 5. 8. Nephridia (singular nephridium ) help The body consists of head, thorax and abdomen 6. They have jointed appendages. 7. Respiratory organs are gills, book gills, book or tracheal system. 8. Circulatory system is of open type. 9. Sensory organs like antennae, eyes muscles which help in locomotion.. 6. Aquatic annelids like Nereis possesses lateral appendages, parapodia which help in swimming. Others (e.g : - carthworm) have setae on the undersurface in osmorgulation and Excretion. 9. Nereis, an aquatic form, is dioecius, but earthworms and leeches are monoecious. 10. Reproduction is sexual. Examples: Nereis. Pheretima (Earthworm) and Hirudinaria (Blood sucking Plus 1 Biology (compound and simple), Statocysts or balance organs are present. Winner’s Coaching Centre Animal kingdom Read and learn with passion • 292 . 10. hump. Excretion takes place through malpighian tubules. 6. The head region has sensory tentacles. 7. The mouth contains a file - like rasping 11. They are mostly dioecious. 12. Fertilisation is usually internal. They are organ called radula (With transverse mostly oviparous. rows of teeth) for feeding. 13. Development may be direct or indirect. Examples Arthropoda; (a) Locust. 8. and spongy layer of skin called mantle. (b) Butterfuly (c) Scorpion (d) Prawn. The visceral hump is covered by a soft 9. Gills are the respiratory organs. 10. The anterior head region has Sensory tentacles, 11. They are dioecious and oviparous. Examples: Pila (apple snail, Pinctada (Pearl oyster), Sepia (cuttlefish), Octo pus (Devilfish), Dentalium (tusk shell), Chaetopleura (chiton), etc. 8. PHYLUM MOLLUSCA 1. Phylum Mollusca forms the Second largest phylum of the animal kingdom. 2. They are terrestrial or aquatic (marine or fresh water). 3. They are bilateral, symmetrical, triploblastic and coelomate animals. 4. Body is covered by a Calcareous shell. 5. Body is unsegmented by consists of distinct head, muscular foot and visceral Plus 1 Biology Winner’s Coaching Centre Animal kingdom The root of joy is to be thankful • 293 . 9. PHYLUM—ECHINODERMATA (spiny bodied animals) 1. All are marine 2. They have endoskeleton of calcareous ossicles and hence the name Echinodermata (spiny bodied). 3. Triploblastic, coelomate, organ system level of organisation. 4. The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical. 5. Digestive system is complete with mouth on the lower (ventral ) side and anus on the upper (dorsal ) side. 10. Presence of Water Vascular system Hemichordata was earlier considered as a which helps in locomotion, capture and sub - phylum under phylum Chordata. But transport of food and respiration. now it is placed as a separate phylum under 7. Excretory system is absent. non - chordata. 8. Sexes are separate. 1. 9. Reproduction is sexual. 10. Fertilisation is usually external. 11. Development is indirect with free - 6. PHYLUM—HEMICHORDATA This phylum consists of a small guoup of worm - like marine animals with organ system level of organisation. 2. swimming larva loblastic and coelomate. 3. trunk. (sea urchin), Antedon (Sea lily), Cucumaria Plus 1 Biology The body is cylindrical, composed of an anterior Proboscis, a collar and a long Examples: Asterias (star fish). Echinus (sea cucumber): and Ophiura (Brittle star). They are bilaterally symmetrical, trip- 4. Circulatory system is of open type. 5. Respiration takes place through gills. 6. Excretory organ is Proboscis gland. Winner’s Coaching Centre Animal kingdom Be the reason behind the happiness of your parents • 294 . 7. Sexes are separate. 8. Fertilisation is external. 9. Development is indirect. Notochord It is the solid and flexible unjointed rode. It is found on the dorsal side between the alimentary canal and nerve cord. Examples: Balanoglossus and Sac Dorsal hollow nerve cord cogloussus. In all chordates the nerve cord is single, dorsal and hollow. It is placed above the notochord. Gill slits All chordates possess paired haryngeal gill slits. They are lateral openings of the pharynx which help in respiration. 11. PHYLUM CHORDATA 1. These are bilaterally symmetrical, triploblastic, coelomate Classification of Chordata with Orgna— system level of organisation. 2. They possess a post anal tail They possess a notochord, on the basis of the fate of the notochord . They are (i) urochordata, (ii) cephalochordate, and a closed circulatory system. 3. Phylum Chordata is divided into 3 sub—phyla and (iii) Vertebrata. i. a dorsal commonly called Protochordates (lower hollow nerve cord and paired pharyngeal slits. Plus 1 Biology Urochordates and cephalochordates are chordates). ii. Protochordates are exclusively marine. Winner’s Coaching Centre Animal kingdom You may learn slowly but don't go back • 295 . Sub - phylum Urochordata (tunicate) sent for locomotion. They are fins or limbs. i. They are marine protochordates. ii. Notochord extends from the anterior v. with 2, 3 or 4 chambers. (head) to the posterior end (tail region) of the body, and is persistent Throughout Presence of a ventral muscular heart vi. life. Kidneys for excretion and osmoregula tion. Example: It is represented by a single genus, Branchiostoma (Amphioxus or lancelet). Classification of Vertebrates Vertebrates are divided into two divisions. (i) Agnatha (lacks jaw) (ii) Gnathostomata (bears jaw) I. Agnatha have one class Cyclostomata. II. Gnathostomata is divided into two super - classes. 1. Pisces (bear fins) 2. Tetrapoda (Bear limbs) Pisces are divided into two sub - classes. 1) Chondrichthyes (Cartilaginous fishes) 2) Osteichthyes. (Bony fishes) Tetrapoda is divided into four sub—classes Sub - phylum Vertebrata i. (i) Amphibia (ii) Reptilia (iii) Aves (iv) They are bilaterally symmetrical, trip- loblastic coelomates. ii. Mammalia Division 1—Agnatha Notochord is only an embryonic structure. In the adult it is replaced by the I. with a Cirucular mouth. Vertebral column (backbone. ) iii. Dorsal hollow central nervous system is Agnathans are Jawless aquatic vertbrates II. It has a single class - cyclostomata. differentiated into brain and spinal cord. iv. Two pairs of lateral appendages are pre Plus 1 Biology Winner’s Coaching Centre Animal kingdom You may learn slowly but don't go back • 296 . Class - Cyclostomata (round mouthed Tetrapoda. fishes). Super Class 1 Pisces (fishes) I. All are ectoparasites on some fishes. II. They have sucking and circular mouth • without jaws. III. IV. They have an elongated body bearing 6 – Their body is devoid of scales and paired Cranium and vertebral column are Carti laginous. VI. It is divided into 2 Classes - Chondrichthyes and Osteichthyes. Class 1 Chondrichthyes (Cartilaginous fish- fins. V. locomotion. • 15 pairs of gill slits for respiration. It Consists of Fishes. They bear fins for es) I. They are marine animals. II. Cold - blooded (poikilothermic) ani mals. They have no capacity to regulate Circulation is of closed type. their body temperature skin is tough and is covered by placoid scales. VII. Cyclostomes are marine but for spawn ing to fresh water. III. are backwardly directed. Examples: Petromyzon (Lamprey) and Myxine (Hagfish). Teeth are modified placoid scales which IV. Endoskeleton is Cartilaginous. I. Notochord is persistent throughout life. II. Mouth is half moon shaped (crescentic) and Ventral in Position. III. Heart is two—chambered (one auricle and one ventricle). Division 2 - Gnathostomata • Gnathostomates possess IV. Jaws and ulate buoyancy (floating) is absent So, paired appendages. • these fishes have to Swim continuously (Constantly ) to prevent (avoid) sinking Notochord is usually replaced by a Ver- to the bottom. tebral column. • Division Gnathostomata is divided into 2 super Classes - Pisces (fishes ) and Plus 1 Biology Air bladder (swim bladder ) Which reg- V. Paired kidneys excrete nitrogeneous waste in the form of urea (ureotelic) Winner’s Coaching Centre Animal kingdom Sooner you start sooner you gain • 297 . VI. They are diecious (sexes are separate). XI Paired copulatory organs called clasp- ers are present between the base of the pelvic fins in males. XII. Fertilization is internal . Examples: Scoliodon (Dog fish), Pristis and one ventricle). VII. They are cold—blooded animals. VIII. Sexes are separate IX. Fertilisation is usually external X. They are mostly oviparous and devel opment is direct. (Saw fish), Carcharodon (Great white Examples: Marine - Exocoetus (Flying shark), Trygon (Sting ray). fish), Hippocampus (Sea horse): Fresh water Labeo (Rohu), Catla (Katla), Clarias (Magur): (Fighting fish), Aquarium Betta Pterophyllum (Angel fish) Class 2 - Osteichthyes (bony fishes) I. Marine and fresh water fishes. II. Endoskeleton is bony, III. Mouth is terminal . They have four pairs of gills which are covered by and operculum on each side. IV. Skin is covered with cycloid / ctenoid V. VI. scales. SUPER CLASS 2 TETRAPODA Air bladder is present which regulates I. Tetrapodes have 2 pairs of limbs. buoyancy. II. They are divided into 4 Classes— Heart is two - chambered (one auricle Plus 1 Biology Amphibia, Reptilia, Aves, and Mam- Winner’s Coaching Centre Animal kingdom Learning is a good habit to success • 298 . malia. Class 1 Amphibia I. They are cold - blooded, amphibious Vertebrates which can live in Water (aquatic and on land (terrestrial ). II. Most of them have two pairs of limbs. Body is divisible into head and trunk. III. Tail may be present in some. IV. The skin is moist (without scales). V. The eyes have eyelids. VI. A tympanum represents the ear. VII. Alimentary canal, urinary and reproduc- Class 2 Reptilia • tebrates. tive tracts open into a common chamber called cloaca which opens to the exteri- • or. They are teresstrial , Cold - blooded (poikilotherms) and oviparous vertebrates. VIII. Respiration is by gills, lungs and through skin IX. Reptiles are creeping (crawling ) ver- • The skin is dry and non - glandular The heart is three—chambered (two (cornified) having an exoskeletal cover- auricles and one ventricle) ing of epidermal scales which form a water - proof coat on the body. X. Sexes are separate. XI. Fertilisation is external • cast, eg: snakes and lizards. XII. They are oviparous and development is indirect. Examples: Bufo (Toad), Rana Frog), Hyla (Tree frog), • Limbs, when present, are two pairs. • The heart is imperfectly 3—chambered with two auricles and an incompletely Salamandra divided ventricle. In Crocodile, heart is (Salamande), Ichthyophis (limbless am 4 - chambered. phibia). Plus 1 Biology Some reptiles shed their scales as skin • External ear is absent. • Tympanum represents the ear. Winner’s Coaching Centre Animal kingdom Take responsibility for your progress • 299 . • Sexes are separate. Fertilisation is inter- • nal. • for flight. Development is direct. Examples: Chelon (Turtle). The fore - limbs are modified into wings The hind—limbs are variously modified for Testudo (Tortoise), chameleon (Tree lizard), Ca lotes Garden lizard), (Crocodilus), Alli gator (Alligator), Hemidactylus (wall lizard, Poisonous snakes - Naja (Cobra), Bangarus (Krait), Vipera (Viper). walking, swimming or clasping on tree branches. • The jaws are modified as beak or bill. • Endoskeleton is fully ossified (bony) • Bones are light, porous and air—filled (pneumatic) in order to reduce the body weight, porous and air - filled (pneumatic) in order to reduce the body weight. • Skin is dry without glands except the oil gland at the base of the tail. • The heart is 4—chambered. • Digestive system has additional chambers - crop and gizzard. • Respiration by lungs. • Air sacs connected to lungs supplement respiration. Class 3 Aves • They are characterized by the presence of feathers. • Most of them can fly except flightless birds. (eg: Ostrich) • They are aerial, warm • Sexes are separate. • Fertilization is internal. Examples: Corvus (Crow). Columba (pigeon), Psittacula (Parrot), Struthio (Ostrich ), Pavo (Peacock), - blooded (Homoiotherms ) and oviparous vertebrates. • The body has an exoskeleton of feathers Plus 1 Biology Winner’s Coaching Centre Animal kingdom Punctuality is respecting your own commitments • 300 . X. Viviparous Platypus and echidna are the only two egg laying mammals Examples: Oviparous - Ornithorhynchus(Platypus) Viviparous - Macropus (Kangaroo) , Camelus (camel), Macaca (Monkey), Rattus(Rats), Ca- nis (Dog), Felis (Cat), Elephas (Elephant), Balaenoptera (Blue whale), Panthera leo (Lion) Class 4 Mammalia I. Skin is provided with hairs II. External ear or pinna is present. III. Presence of milk producing mammary glands. In females these glands secrete milk for the nourishment of the young. IV. They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying. V. Different types of teeth present in the IMPORTANT QUESTIONS jaw. VI. 1. Heart is four chambered. VII. Respiration by lungs. VIII. They are homoiothermous (warm blooded) IX. Sexes are separate, fertilization is inter- Observe the picture A and B. a) Identify the phylum of A and B. b) Comment on the symmetry. c) Compare the type of coelom in A and B. nal Plus 1 Biology Winner’s Coaching Centre Animal kingdom Be afraid not to try • 301 . 4. Fill the blank space in the table given below. Orgn / Struc- Function ture (a)…. Rasping organ in Mol- luscs A 2. B (b) …. Stinging cap- Identify the cell, Name the phylum to sule of Cni- which it belongs? daria Who am I ? I live in the sea. I have organ—system level of organiza- a. Phylum in which flatworms are included. b. Excretory organs of annelids. c. Largest Phylum. d. An oviparous mammal. e. Chordate animal having flame cells as 6. tion. I respire through gills I excrete by proboscis gland. My body is composed of proboscis, collar and a long trunk. Plus 1Biology Name the following: the excretory organ 3. a) Name the phyla 5. Complete the table, A B C Collar cells …(a) .. Digestion (b) ….. Echinodermata Locomotion ….. Arthropoda …(c) . Radula (d)…... Feeding b) give one example Winner’s Coaching Centre Animal kingdom Be a student in life to learn something new • 302 . 7. A shark has to swim continuously unlike 13. a sardine. Give reason. 8. ed two organisms. Observing the morphology, it is clear that the organisms are Bats and whales belong to the same radially symmetrical. class. a) b) Give reasons But all b) which the other organisms can be include statement with an example. ed. Your are given the Specimens of Scolio c) don and Catla. Distinguish between organisms will help you to categories it these two, on the basis of the following into a particular phylum? 14. Which distinctive feature of this “All vertebrates are chordates but all (a) Operculum (b) scales (c) air bladder chordates are not vertebrates "Evaluate (d) fertilization and substantiate the statement. Name the following . 15. b) Name the distinctive character (responsible for their names) of the fol a) An egg laying mammal. lowing animal groups: A flying mammal PREVIOUS YEARS QUESTIONS 12. Identify the possible phyla to chordates are not vertebrates. Justify this features. 11. To which phylum does this organ ism belong? All vertebrates are chordates. 10. One of them shows bioluminescence. a) Identify the class 9. During a seashore visit, a student collect- (a) Pick out the acoelomate organism from the following: i) Roundworm ii) Hookworm iii) Filarial worm iv) Tapeworm a) Cnidaria b) Arthropoda c) Porifera d) Annelida e) Chordata f) Ctenophora Or Your Biology teacher exhibited a laboratory specimen in the classroom. Based b)Name the phylum to which it belongs. on which features will you distinguish it c)Mention its mode of nutrition. as a chordate or a non - chordate? d) What is the coelomic condition of other organisms? swer. Substantiate your an- 16. Prawns and insects are included in the phylum Arthropoda while they have dif ferent habits and habitats. Justify your answer. Plus 1 Biology Winner’s Coaching Centre Animal kingdom Be afraid not to try • 303 . 17. Figures (X) and (Y) are the fish of two 22. different classes. Identify them and dif The following diagram shows the charac teristic features of a phylum. ferentiate between these classes. a) Identify the phylum. b) Mention four salient features of this phylum. X Y 18. Birds are well adapted for flying. Give 23. with A. any three of such adaptations. A B C Phylum / Class Common example Unique feature statement with an example. Pisces Aedes Presence of hair The characteristic features of an inverte Mammalia Leech Open circulatory system Arthropoda Felis Presence of two - chambered heart Scoliodon Presence of Nephridia Or All vertebrates are Chordates, but all chordates are not vertebrates. Justify this 19. Match the items in columns B and C brate is given. “The phylum includes the comb jellies, also called walnuts. They are noted for their bioluminescence and comb plates”. Identify the phylum. 20. Fill in the blanks with appropriate word: Osteichthyes : Cycloid scales 24. Chondrichthyes : ——— 21. —have pseudocoelom. Name the phyla in which the following cells / Structures / organs are present: a) Radula c) Pneumatic bone Plus 1 Biology Among the different phyla of animals — b) Cnidoblast 25. Categories the following animals under radial symmetry and bilateral symmetry - Physalia, Tapeworm, Fasciola, Ad amsia d) Proboscis gland Winner’s Coaching Centre Animal kingdom Be afraid not to try • 304 . 26. Note the relationship in the first pair and then complete the second pair. Osteichthyes : Cycloid scales Chondrichthyes : ——— 27. Arrange the following terms under two headings based on symmetry. Arthropods, Ctenophores, Molluscs, Coelenterates. 28. 31. Complete the flow chart given below. 32. Find the odd one from each group. Justi (a) A table showing examples of verte brates is given below. But some of the examples are wrongly given. Identify and rearrange it. Pisces Am- Reptilia Aves phibia Dog Frog malia Vulture Pen- fish Blue Rohu whale MamAlliga- guin tor Tor- Sala- Flying toise mander fox (b) Which of the above mentioned class is characterized by the presence of pneu matic bones? 29. “All vertebrates are chordates; but all chordates are not vertebrates”. Do you agree with this statement? Substantiate. 30. Observe the figure of the organism given below. fy your answer. a) Identify the organism. b) Name the class in which it belongs. c) Mention any two salient features of the class. Plus 1 Biology a) Star fish, Devil fish, Dog fish, Jelly fish b) Flying fish, Angel fish, Saw fish, Fighting fish. Winner’s Coaching Centre Animal kingdom Be a student in life to learn something new • 305 . c) Sea lily, Sea cucumber, , Sea hare, Sea urchin. 33. a. Identify the organisms A,B and C. b. Name the phylum to which each of Identify the word pair applicable to ph them belong. ylum Ctenophora. (a) Nephridia, Parapodia ANSWERS (b) Comb plates, Bioluminescence (c) Polyp, Metagenesis 1. (d) Radula, Visceral hump 34. b) A—Radial Symmetry. B—Bilateral Characteristics of certain animals are sym metry. given. c) A—Acoelomate. B - True coelomate. Arrange them under the ‘Class’ to which these animals belong. i. Skin is moist without scales. ii. Body is covered by dry and corni 2. Cnidoblast. Phylum - Coelenterata 3. a) Phylum - Hemichordata b) Balanoglossus fied skin. 4. a) Radula iii. Shed the scales as skin cast. 5. a) Phylum - Platyhelminthes iv. Can live in aquatic as well as ter b) Cnidoblast b) Nephridia restrial habitats. 35. a) A—Coelenterata. B - Annelida. c) Phylum - Chordata Observe the figures. d) Platypus e) Amphioxus 6. a) Porifera b) Tube feet c) Respiration d) Mollusca 7. Because, sharks do not have swim bladder (air bladder) to regulate buoyancy. 8. A B C a) Class Mammalia. b) 1. They are viviparous vertebrates. 2. The respiratory system, excretory Plus 1 Biology Winner’s Coaching Centre Animal kingdom Keep calm and respect others • 306 . c) Based on presence or absence of tube system, nervous system and reproductive 9. system are well - developed. feet, spiny exoskeleton, tentacles, nema All chordates have a notochord but not can categories the second organism into vertebral column. its particular phylum. tocyst, shape (e.g., Star shape), etc., We In vertebrates noto chord is replaced by vertebral column. Chordates are classified into urochord 14. embryonic stage. But all chordates lack dates, cephalochordates and vertebrates. vertebral column. Chordates like Uro- In urochordates and cephalochordates a chordata and cephalochordate lack verte- ‘no - tochord’ is present. It persists in bral column. Vertebrates are chordates cephalochordates and disappears in the with vertebral column. adult of urochordates. 15. 10. Features 1) Scoliodon Opercu- Absent All vertebrates have notochord in the A) Cnidoblast / Stinging cells B) Jointed foot Catla Present C) Porous body D) Metamerism / Segmented 2) Scales Placoid Cycloid scales scales 3) Air blad- Absent Present E) Notochord F) Comb plates Or 4) Fertiliza- Internal External tion Differences between chordates and non chordates 11. a) Platypus 12. a) Tapeworm b) Bats b) Phylum Platyhelminthes c) Parasitic d) All are pseudocoelomate. 13. a) Phylum Ctenophora b) Coelenterata (Cnidaria) Or Echino dermata Plus 1 Biology Winner’s Coaching Centre Animal kingdom Learn and share from your heart • 307 . Chordata Non - Chor- Notochord Present Nerve cord Dorsal tubu- Double ven- Absent lar tral Present Absent Post anal tail Present Absent Gill slits 18. • Presence of wings • Body is covered by feathers • Pneumatic bones Or All vertebrates have notochord in the embryonic stage. But all chordates lack vertebral column. Chordates like Uro chordata and cephalochordate lack verte bral column. Vertebrates are chordates 16. Both insects and prawns have: with vertebral column. Man is an exam 1. Jointed appendages ple for vertebrate. 2. Haemocoel present 19. Ctenophora 3. Segmented body with head, thorax and 20. Placoid Scales abdomen. 21. A) Mollusca 17. B) Cnidaria / Coelenterata Chondrichthyes Osteichthyes C) Chordata / Aves - Birds 1. Endoskeleton is cartilage 1. Bony endoskeleton D) Hemichordata. 2. Five pairs of gills without operculum 2. Four pairs of gills operculum 22. b) (i) Presence of dorsal hollow nerve cord 3. Mouth is ventral 3. Mouth is terminal 4. Heterocercal caudal fin (ii) Presence of notochord 4. Homocercal caudal fin (iii) Presence of paired pharyngeal gill slits. 5. Body is covered 5. Body is covered by placoid scales by ctenoid scales 6. Air bladder absent 6. Air bladder present. 7. Fertilization is internal 7. Fertilization is external Plus 1 Biology a) Phylum Chordata (iv) Presence of post anal tail 23. Winner’s Coaching Centre Animal kingdom You become what you study • 308 . dates with vertebral column. A B C Pisces Scoliodon Presence of two - cham- Mammalia Felis Presence of hair Arthropoda Aedes Open circulatory system 30. A) Hippocampus / Seahorse B) Class Osteichthyes C) Bony endoskeleton Presence of air bladder 31. a) Gnathostomata b) Cyclostomata c) Tetrapoda 24. Aschelminthes 25. Radial symmetry : Physalia, Adamsia 32. d) Osteichthyes a) Dog fish - Dog fish belongs to phylum Chordata which is characterized by presence of notochord. Bilateral symmetry : Tapeworm, Fasciola Others are non— chordates. 26. Placoid scales 27. Radial Symmetry : - Ctenophores, Coe- drichthyes lenterates maining are Osteichthyes (bony fishes). Bilateral symmetry : - Arthropods, Mol c) Sea hare - Phylum Mollusca, Remain luscs. ing ones - Phylum Echinodermata 28. b) Saw fish - Belongs to Class Chon (a) Pisces Dog Am- Reptil- Aves Mam- phibia ia malia Frog Alliga- Pen- Blue tor guin whale Tor- Vulture Flying fish Rohu Sala- mander toise fox 33. b) Comb plates, Bioluminescence 34. Class Amphibia (i) & (iv) Class Reptilia (ii) & (iii) 35. A - Balanogloussus - Phylum Hemichordata B - Nereis - Phylum Annelida C - Liver Fluke / Fasciola - Phylum Plat (b) Class - Aves / Birds 29. ( Cartilaginous fishes). Re yhelminthes (Flat worms.) Yes. All vertebrates have notochord in the embryonic stage. But all chordates lack vertebral column. Chordates like Urochordata and cephalochordate lack vertebral column. Vertebrates are chorPlus 1 Biology Winner’s Coaching Centre Animal kingdom I’m proud of the way you worked today • 309 . CHAPTER - 5 MORPHOLOGY OF FLOWERING PLANTS Morphology is the branch of biology, which deals with the study of external form and structure. 1. Tap root system • The primary root and its branches constitute the tap root system. The flowering plants are collectively called as angiosperms. • The tap root system has a main root called taproot or primary root. It is the Parts of a flowering plant direct prolongation of the radicle. A typical flowering plant has following two • The root system is characteristic of dicotyledons eg. Mustard plant. parts. The root system—It is underground part, usu- 2. Fibrous root system ally below the soil. It originates from the radi- • Monocots have fibrous root system. • The primary root dies off early, Later cle of the embryo. The shoot system - It is the aerial, usually numerous hair like roots arise from the above the soil. It originates from the plumule base of the stem. of the embryo. • All the fibrous roots are thin. They do Root not grow into the deep soil. Eg. , Wheat I. It is positively geotropic. plant. II. On germination of a seed, the first root arises from the radicle of the embryo and 3. Adventitious root system • These roots arise from any part of the grows downwards. This is called as the plant other than the radicle, Primary root. III. Eg: grass. Monstera, banyan tree etc.. It bears lateral roots of several orders that are known as Secondary, tertiary roots etc. There are three types of root systems. They Functions of the root system 1. To anchor the plant to the soil. 2. To absorb water and nutrients from the are taproot system, fibrous root system and adventitious root system. Plus 1 Biology soil. 3. Storing reserve food materials. Winner’s Coaching Centre Morphology of flowering plant I’m proud of the way you worked today • 310 . 4. Synthesis of plant growth regulators 5. Some roots get modified to perform spe- tion is called the region of maturation. • From this region some of the epidermal cial functions such as respiration, me- cells form very fine and delicate, thread chanical support, assimilation and like structures called root hairs. storage of food. root hairs absorb water and minerals The from the soil. Regions of the root THE STEM I. Stem bears branches, leaves, flowers and fruits. II. The stem bears nodes and internodes. III. The region of the stem where leaves are born are called nodes. IV. Region between two adjacent nodes is termed internode. Functions of the stem I. It acts as a supporting structure for the 1. Root cap (Calyptra) branches which bear leaves, flowers and • The tip of the root is protected by a thim- fruits and expose them to sunlight. ble like structure called root cap. II. It protects the tender root apex as it III. In many plants the stem is modified for makes its why through the soil. doing special functions such as storage of 2. Meristematic region food, support protection and vegetative propa- • This region occupies a few millimeters • • It conducts water, minerals. gation. above the root cap. THE LEAF The cells of this region are very small, I. thin walled and with dense cytoplasm. The cells divide repeatedly. Region of Maturation • The zone proximal to region of elonga- Plus 1 Biology outgrowth borne on the stem. II. 3. The leaf is a lateral generally flattened It develops at the node and bears a bud in its axil called axillary bud. The axillary bud later develops into a branch. Winner’s Coaching Centre Morphology of flowering plant Keep working on it, you’re almost there! • 311 . III. They are the most important vegetative organs since they are adapted for performing the vital functions such as transpiration, Photosynthesis respiration. called lamina or leaf blade. • The lamina bears veins and veinlets. • There is a middle prominent vein known as Midrib. Parts of a Leaf • Veins provide rigidity to the leaf blade A typical leaf consists of three parts a leaf and act as channels of transport of wa- base, Petiole and lamina. ter, minerals and food materials. Leaf base (Hypopodium) • • • The basal part of the leaf that connects it The edge of lamina is known as leaf with the stem is called leaf base. margin. Small lateral outgrowths are developed on either side of the leaf base, called the stipules. • Venation The mode of arrangement of the veins and veinlets in the lamina is called venation. In monocotyledons the leaf base expands in to a sheath covering the stem partially • The tip of the leaf is called leaf apex. The venation is of two types. or wholly. This is called sheathing leaf Reticulate venation base. In reticulate venation the veinlets form a net- In some leguminous plants the leaf base work. It is a characteristic feature of dicotyle- may become swollen, which is called dons. pulvinus. Eg: Hibiscus, Cucumber. Petiole (Mesopodium) Parallel venation • The stalk of the leaf is called the Petiole. When the veins run parallel to each other • A leaf having petiole is called Petiolate. within a lamina, the venation is called paral- • The leaf without the petiole is called Ses- It is a characteristic feature of monocotyle- sile. • lel. The petiole help to hold the leaf blade to dons. Eg: Banana, grasses etc. light. Lamina or leaf blade (Epipodium) • The green, expanded part of the leaf is Plus 1 Biology Winner’s Coaching Centre Morphology of flowering plant Nothing can stop you now • 312 . In pinnately compound leaf the leaflets are arranged at the tip of the rachis, like the fingers in our palm. Eg: Silk cotton Types of leaves Leaves are of two types. They are simple leaves and compound leaves. Phyllotaxy 1. Simple leaves A leaf with single lamina is said to be simple leaf. The pattern of arrangement of the leaves on the stem is called Phyllotaxy. types - Alternate, Opposite and Whorled. Eg: Hibiscus. Alternate phyllotaxy. 2. Compound leaves Here a single leaf arises at each node in alter- A leaf with two or more lamina or leaf segments is called a compound leaf. nate manner. Eg: China rose, mustard, sunflower These leaf segments are called leaflets. Compound leaves are of two types. Opposite phyllotaxy Here a pair of leaves arise at each node and lie Pinnately compound leaf opposite to each other. In pinnately compound leaf a number of leaf- Eg: Calotropis, guava plants lets are present in a common axis called rachis, which represents the midrib of a leaf. Eg: Neem tree. Palmately compound leaf Plus 1 Biology This is of three Whorled Phyllotaxy If more than two leaves arise at a node and form a whorl, It is called whorled phyllotaxy. Eg: Alstonia Winner’s Coaching Centre Morphology of flowering plant Whatever you do, do it well • 313 . INFLORESCENCE An axis bearing a cluster of flowers are known as inflorescence. Cymose inflorescence In Cymose inflorescence peduncle terminates Eg: Crotalaria. in a flower. The common axis of the inflorescence is called The terminal flowers are arranged laterally peduncle. towards the base. This type of development The flowers may arise from the axil of leaf like is called basipetal succession. structure called bract. FLOWER Based on the nature of the peduncle the inflo- • unit in the angiospersms. rescence may be divided into two groups. They are racemose and cymose. • A flower is a modified reproductive shoot. The stalk of the flower is called Racemose inflorescence pedicel. The peduncle does not terminate in a flower. The peduncle tip continues growing and pro- • the younger flowers near the tip and the older flowers at the base. This development The upper part of the pedicel is swollen or flattened and is known as Thalamus. duces flowers laterally. The peduncle bears • The thalamus bears four floral whorls. They are calyx, corolla, androecium of flowers is called acropetal succession. Plus 1 Biology The flower is the sexual reproductive and gynoecium. Calyx: Composed of sepals Corolla: composed of petals Winner’s Coaching Centre Morphology of flowering plant Every moment is a fresh beginning • 314 . Androecium: Composed of stamens Bracteate - A flower with a bract (bract is a (male reproductive part) reduced leaf found at the base of the pedicel) Gynoecium: Composed of carpels (Female reproductive part) Ebracteate - A flower without a bract. Position of floral leaves on the thalamus Terms for describing a flower Based on the position of floral leaves on the Bisexual - A flower with both androecium and thalamus flowers may be of following three gynoecium. types. Unisexual - A flower with only androecium or 1. Hypogynous Flower. gynoecium Actinomorphic (Radial symmetry ) - A flower that can be divided into two equal radial halves • The ovary is located at the top. • Here the other floral parts such as calyx corolla and androecium are attached to in any radial plane passing through the centre. Eg: Mustard, Datura, Chilli etc. the thalamus below the ovary. • Zygomaorphic - A flower that can be divided The ovary is superior Eg: Mustard , China rose and Brinjal into two equal halves only in one vertical plane. 2. Perigynous flower Eg: Pea, Gul mohar. Bean, Cassia etc. • The ovary is situated at the bottom of the concave thalamus without fusing with Asymmetric (irregular) - A flower that cannot other floral parts such as calyx, corolla be divided into two similar halves by any verti- and androecium. cal plane passing through the centre. • Eg: Canna The ovary is said to be half inferior. E.g: Plum, Rose, Peach etc. Trimerous - A flower in which number of parts in each whorl is 3 or its multiple. 3. Epigynous flower Eg: Monocots • and is fused with the ovary. Tetramerous –A flower in which number of parts in each whorl is 4 or its multiple. • Eg: In most dicots Plus 1 Biology The other parts of the flower arise above the ovary. Pentamerous - A flower in which number of parts in each whorl is 5 or its multiple. Thalamus become deeply cup - shaped • The ovary is inferior . Eg: Guava, Cucumber and the ray flo Winner’s Coaching Centre Morphology of flowering plant There is no substitute for hard work • 315 . rets of Sunflower. • The corolla is the second whorl of a flower inner to the calyx. • It is composed of petals. The petals are brightly coloured to attract insects for pollination • When the petals are free the corlla is termed Polypetalous. If the petals are fused, the corolla is termed gamopetalus. Aestivation The mode of arrangement of sepals or petals Parts of a Flower Each flower has four whorls. They are Calyx, Corolla, Androecium and Gynoecium. in a flower bud is called aestivation. The main types of aestivation are valvate, twisted, imbricate and vexillary. Calyx • The calyx is the outermost whorl of a flower. • It is composed of Sepals. • Sepals are green, leaf like, They protect the flower in bud stage. • When the sepals are free the calyx is said to be Polysepalous. If the sepals are fused, the calyx is said to be gamosepalous. Corolla Plus 1 Biology Winner’s Coaching Centre Morphology of flowering plant Whatever you are, be a good one • 316 . als (wings) which in turn overlap the two smallest anterior petals (keel), Eg: Pea and bean flowers. Valvate aestivation When the edges of sepals or petals just meet one another without overlapping, the aestivation is known as valvate. Eg: Calotropis Androecium Twisted aestivation. • If one margin of an appendage overlaps that of The androecium is the third whorl inner to the corolla. the next one and so on, it is called twisted aes• tivation. men is the male reproductive part of Eg: China rose, Lady’s finger and cotton. Imbriacate aestivation the flower. • If the margins of sepals or petals overlaps one • Each anther is usually bilobed and each lobe has two chambers, the pol- Here one of the appendages is completely in- side, One Completely outside Each stamen has a slender stalk called the filament and an anther. another but not in any particular direction, it is called imbricate aestivation. It is composed of stamens. The sta- len sacs. The pollen grains are pro- and the re- duced in pollen sacs. maining ones regularly overlaps. Eg: Cassia and gulmohur. Vexillary aestivation (Papilionaceous aestiva- Adhesion of stamens tion) Stamens may be united with the other mem- • Here there are five petals; the largest bers such as petals, sepals or gynoecium. (Standard) overlaps the two lateral pet- 1. Plus 1 Biology Epipetalous: The stamens are fused with Winner’s Coaching Centre Morphology of flowering plant Education is the key to success • 317 . the petals . Eg: Brinjal. 2. • is said to be apocarpous. Epiphyllous: The stamens attached to the perianth. Eg: Lily. Eg: - lotus and rose. Cohesion of stamens • If all the stamens in a flower are free, the androecium is said to be Polyandrous. The fusion of stamens may be Eg: Mustard and tomato. Placentation • of following types, The mode of arrangement of ovules on the placenta within the ovary is known as Monadelphous: All the filaments of stamens placentation. are fused to form a single bundle. • Eg: China rose If the carpels are fused it is called syncarpous gynoecium. Fusion of the members of the similar whorls is called cohesion. If the carpels in a gynoecium are free, it The different type of placentation is as follows. Diadelphous: The filaments of stamens are fused to form two bundles. Marginal placentation The ovary is one chambered (unilocular). The Eg: Pea placenta forms a ridge along the ventral suture Polyadelphous: The filaments of stamens are of the ovary and the ovules born on this ridge fused to form many bundles. forming two rows. Eg: Citrus. Eg: - Pea Gynoecium Axile placentation • • Gynoecium is the innermost whorl of a It is found in multicarpellary syncarpous and flower. multilocular ovary. The placenta bearing the It is the female reproductive part of the flower. It is composed of carpels. • Each carpel has an ovary, style and stig- The basal swollen ovary encloses the ovules. Stigma is the receptive surface Plus 1 Biology Parietal Placentation It is usually seen multicarpellary and syncar- ma. of pollen grains. ovary . Eg: - China rose. • • ovules develop from the central axis of the pous pistil. The Basal ovary is unilocular. The ovules on the placenta are originated at the point of fusion of the margins of the carpels Winner’s Coaching Centre Morphology of flowering plant There is no substitute for hard work • 318 . on the inner surface of the ovary. The one chambered ovary may become two chambered due to the formation of the false septum. Drupe Drupe is a simple fleshy one seeded fruit developed from monocarpellary superior ova- Eg: Mustard and Angemone ry. Free - central placentation Where the Pericarp is differentiated into outer Ovary is unilocular and placenta arises from the base of the ovary , Projects in to the cavity epicarp. Middle mesocarp and inner endocarp. Eg: Mango, Cocunut, [Edible portion of man- as a swollen axis and bears ovules. go is the mesocarp] Eg: Dianthus and Primerose Basal Placentation Ovary is unilocular. The placenta develops at the base of the ovary and bears a single ovule. Eg: Sunflower, Marigold SEED The seed is a mature ovule containing embryo. Seeds are of two types. (i) Endospermous seeds and (ii) non endo- FRUIT A fruit is a ripened ovary developed after ferti- sperms seeds. lization. Endosperms seeds: A seed with endo- Parathenocarpic fruit sperm is called Albuminous seed. A fruit formed without ferilisation is called Food is stored in the endosperm. parthenocarpic fruit Eg: Wheat, maize, barley, castor, sunflower Structure of fruit. etc. Fruit consists of outer pericarp and inner Non endosperms seeds: A seed without seed. Pericarp is differentiated into outer epi- endosperm is called non albuminous seed. carp, middle mesocarp and inner endocarp. Plus 1 Biology Eg: pea, groundnut, beans, sunflower, cash- Winner’s Coaching Centre Morphology of flowering plant Strive for learning and not for grades • 319 . ew nut etc. Structure of Dicotyledonous seed • Seed coat is the outermost layer of the seed having two layers, outer testa and inner tegmen. • Hilum is a scar on the seed coat by which the developing seeds are attached to fruit. • Micropyle is a small pore above hilum. • Embryo is present inside seed coat with embryonal axis and two cotyledons. Semi - technical description of a typical • Cotyledons are fleshy and consist of reserve food materials. • Floral Diagram Two ends of embryonal axis bear redicle and plumule. Monocot seeds may be endospermous or non endospermous. • The diagrammatic representation of floral parts in a flower bud is called Floral diagram. Structure of Monocotyledonous seed • flowering plant foral Diagram Floral Formula The representation of floral parts with their appropriate symbols is called floral formula Seed coat is membranous and fused with fruit wall. • Aleurone layer is the proteinaceous layer separating embryo and endosperm. • Embryo is small and consists of one large shield shaped cotyledon called axis with a plumule and radicle. • Plumule and radicle are enclosed in sheaths called coleoptile and coleorhiza. Plus 1 Biology Winner’s Coaching Centre Morphology of flowering plant Be better than yesterday • 320 . aestivation Corolla: Petals five, united; valvate aestivation Androecium: stamens five, epipetalous Gynoecium: bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules Fruits: berry or capsule Seeds: many, endosperms Floral formula: . II. SOLANACEAE It is a large family, commonly called as the ‘potato family’ Economic importance Vegetative Characters Edible plants Plants mostly, herbs, shrubs and small trees 1. Stem: herbaceous rarely woody Aerial, erect, cylindrical, branched, solid or hollow hairy of glabrous, underground stem in potato (Solanum tuberosum) Solanum tuberosum (potato): Stem tuber is used as food throughout the world. Medicinal plants 1. Atropa belladonna (belladonna): Atropin extracted from roots is used in the Leaves: alternate, simple, rarely pinnately preparation of compound, exstipulate; venation reticulate 2. Withania somnifera (ashwagandha): Leaves are used in fever and skin diseas- Floral Characters es. Inflorescence: Solitary, axillary or cymose as in Solanum Fumigatory plants 1. Flower: bisexual, actinomorphic Nicotiana tobacum (tobacco) Ornamental plants Calyx: Sepals five, united, persistent, Valvate Plus 1 Biology Winner’s Coaching Centre Morphology of flowering plant Always have an attitude of gratitude • 321 . 1. Petunia violacea a) Food is stored by plants. 2. Cestrum nocternum b) Leaves are born c) Xylem and phloem are present d) Axillary buds develop 4. In which plant underground stem spreads to new niches and when older parts die new plants are formed. a) Grasses b) Strawberry c) pistia d) Both (a) and (b) 5. Petiole IMPORTANT QUESTIONS 1. Which of the following is incorrect? a) Roots helps in water and mineral ab6. sorption from soil. a) Helps to hold the leaf blade b) Allows leaf blades to flutter wind c) Helps in cooling the leaf d) All of the above Perianth is the condition in which? b) Roots provide a proper anchorage. a) Calyx and corolla are not distinct c) Roots store food material and syn- b) Calyx is present, but corolla is ab sent. thesise plant growth regulators. d) Roots lack meristematic activity. 2. sent. Which of the following is the smallest d) Calyx and corolla are not present. region of the root? 7. Fill in the blank. a) Root cap 3. c) Corolla is present, but calyx is ab b) Region of elongation Location of thalamus is ……………. c) Region of meristematic activity a) Higher than other floral whorls d) Region of maturation b) Lower than other floral whorls Nodes are the region of stem where Plus 1 Biology c) Same as the other floral whorls Winner’s Coaching Centre Morphology of flowering plant Take every problem as a challenge • 322 . d) None of the above 8. Match the following A. Pedicel 1. reduced leaf B. Peduncle 2. Stalk of the flower C. Bract 3. Stalk of the leaf D. Petiole 4. Inflorescence ax14. The term ‘Polyadelphous’ is related to 9. How is pinnately compound leaf different from palmately compound leaf? 10. Give the technical term of the following: 2. Flowers cannot be divided into two equal halves. 4. Carpels are fused. 11. Justify the following statements on the basis of external features. Underground parts are not always roots. Flower is a modified shoot. 12. Differentiate between Racemose and cymose inflo- Apocarpous and syncarpous ovary. 13. Label the regions of the root tip in the given diagram. Plus 1 Biology 16. The wheat grain has an embryo with one a) Epiblast b) Coleorhiza c) Scutellum d) Coleoptile 17. Non - albuminous seed is produced in a) Maize b) Castor c) Wheat d) Pea 18. Which of the following is a correct combi- rescence 2. d) Citrus large shield - shaped cotyledon known as floral whorls. 1. d) Calyx a) Dianthus b) Argemone c) Brassica 3. Position of ovary is higher than other 2. c) Corolla 15. Free - Central placentation is found in 1. Two leaves at each node. 1. a) Gynoecium b) Androecium nation of family and its respective members a) Fabaceae - Tomato , chili b) Solanaceae - Tobacco, Brinjal Winner’s Coaching Centre Morphology of flowering plant Take every problem as a challenge • 323 . c) Liliaceae - Petunia, potato d) None of the above c) 24. Name the three kinds of petals in B. Observe the figures A and B. 19. Endosperm, a product of double fertilization in angiosperms is absent in the seeds of a) coconut b) Orchids c) Maize d) Castor 20. Note the difference between the placenta and thalamus. A 21. Mango and coconut are ‘drupe’ type of a) fruits. Which are the 3 layers of pericarp. b) words and fill up the suitable word in the 25. Define venation . Write three peculiarities of gynoecium seen in Solanaceae 1. Shoot - Plumule : Root - 2. Outer integument - Testa : Inner integ- 26. Observe the relationship between the first two terms and fill in the blank. ument 3. Name the type of venation in A and B. 22. Observe the relationship between first two fourth place. B Epipetalous stamen - Brinjal Ovule - Seed : Ovary - ———————— - Lily PREVIOUS YEARS QUESTIONS 27. Match the following: 23. Observe the figures A and B . A (i) Vexillary b) China rose (ii) Valvate c) Cassia (iii) Twisted d) Pea (iv) Imbricate 28. B a) Identify the aestivation A and B. b) Write one peculiarity of A. Plus 1 Biology a) Calotropis a) The arrangement of flowers on the floral axis is called. (i) Aestivation Winner’s Coaching Centre (ii) Phyllotaxy Morphology of flowering plant Be the light for your family • 324 . (iii) Placentation (iv) Inflorescence 32. Use appropriate terms for the following b) How can you differentiate an actino 29. description : morphic flower from a zygomorphic A) Axillary buds of stems modified as flower? slender and spirally coiled structure for helping plants to climb. Observe the floral diagram and answer the following questions: B) Axillary buds of sems modified as woody straight and pointed structure to protect plants from browsing animals. 33. Observe the diagram and answer the questions. a) Name the family. b) Write down the speciality of stamen. 30. The following figures show two type of aestivation. Answer the following questions: a) Identify the types A and B. b) How will you distinguish A and Name the aestivation given and write one example for the same. 34. Name the parts of a monocot embryo in the given diagram . B? 31. Observe the following diagrams ‘a’ ‘b’ . Identify the placentation. and 1. ——— 2. ——— 3. ——— 4. ——— 35. Given below is the arrangement of petals of a flower as drawn by your classmate. A Plus 1 Biology B Winner’s Coaching Centre Morphology of flowering plant Be giving, enjoy sharing • 325 . ANSWERS A) Identify the aestivation 1. d) Roots lack meristematic activity 2. c) Region of meristematic activity 3. b) Leaves are born flower is known as ——— 4. d) Both (a) and (b) B) 5. d) All of the above 6. a) Calyx and corolla are not distinct 7. b) Lower than other floral whorls B) Give reason for the identification. 36. Fill in the blanks A) The arrangement of petals in the Identify the types of the arrange ment of petals shown in the following diagrams: 8. 37. Bentham and Hooker’s Classification is A. Pedicel 2. Stalk of the flower B. Peduncle 4. Inflorescence axis C. Bract 1. Reduced leaf D. Petiole 3. stalk of the leaf mainly based on ——— 38. Arrangement of flowers on the peduncle varies depending upon the nature and branching of the peduncle. Can you substantiate your 9 answer with suitable examples. 39. Identify the region ‘A’ marked in the figure and write down its function. either side of a common axis, rachis, it is pinnately compound leaf. Rachis represents the midrib of leaf. E.g. , Neem 10. Plus 1 Biology When a number of leaflets are present on Opposite phyllotaxy Winner’s Coaching Centre Morphology of flowering plant Make time for yourself • 326 . 2. Asymmetric. 14. b) Androecium 3. Hypogynous flower. 15. a) Dianthus 4. Syncarpous. 16. c) Scutellum 11. Underground stem get modified for different purposes like food storage reproduction and perennation. They can be recognized from 17. d) Pea 18. (b) Solanaceae - Tobacco, brinjal root in having nodes, internodes , scale leaves, 19. b) Orchids terminal bud and axillary bud. E.g., Rhizome - 20. Placenta : Region with which ovules are Ginger, Stem tuber - Potato. attached to ovary. 2. A flower can be considered as a modified Thalamus: shoot because each whorl of a flower repre- are attached. sents each node. The leaves at each node is modified to perform functions like protection, attraction and reproduction. 21.Endosperm The internodes 2. Liquid endosperm (free nuclear endo are compressed to form a flower. 12. 1. Racemose: sperm) The axis or peduncle shows indefinite growth. 22. 1. Radicle Flowers are 2. Tegmen arranged in acropetal succession. 4. Fruit Cymose: The axis or peduncle shows definite growth or ends in a flower. 23. a) (A) Twisted Flowers are arranged in basipetal success (B) Vexillary / Papilionaceous sion. 2. (b) One margin of each member overlaps Apocarpous: When the carpels of that of the next one. the ovary are free. Syncarpous: (c) Standard petal, wing (lateral) petals, When the carpels of the keel petals (anterior small petal). ovary are fused. 13. a) Root cap 24. a) (A) Reticulate venation (B) Parallel venation. b) Meristematic region b) Arrangement of veins and veinlets in c) Region of elongation d) Root hair region Plus 1 Biology Region where floral parts the leaf lamina. 25. Solanaceae: Winner’s Coaching Centre Gynoecium - Bicarpel Morphology of flowering plant Respect your parents, world will respect you • 327 . lary , hypogynous, axile placentation, bilocular, syncarpous, superior ovary, swollen placenta, many ovules, G(2). 26. Epiphyllous / Epipetalous /Statements attached to tepals or perianth entation . 32. (a) Tendrils (b) Thorns 33. Vexillary aestivation e.g., Pea. 34. 1. Coleoptile 2. Plumule 3. Radicle 4. Coleorhiza 27. a) Calotropis 35. (ii) Valvate (a) Imbricate (b) Overlap one another in any particular b) China rose (iii) Twisted c) Cassia (iv) Imbricate direction. One out, one in and others half in and out. 36. d) Pea 28. (i) Vexillary 37. (a) (iv) inflorescence (a) Aestivation (b) (A) Valvate (B) Twisted (C) Imbricate (D) Vexillary Vegetative characters and floral characters. (b) Actinomorphic Flower can be divided into two equal radial halves in any radial plane passing 38. The arrangement is of two types Racemose and Cymose. In racemose, the peduncle does not ter- through the centre. minate in a flower. Zygomorphic It continuously growing and produces flower laterally on Flower can be divided into two similar halves only in one particular vertical plane. acropetal succession. E.g., Jasmine. 39. Region of maturation 29. (a) Solanaceae Function: Root hairs absorb water and (b) Epipetalous minerals. 30. (a) Valvate [A] , Twisted [B] (b) A - No overlapping of margins. B - Margins overlap 31. (a) Axile placentation (b) Parietal plac- Plus 1 Biology Winner’s Coaching Centre Morphology of flowering plant Be afraid not to try • 328 . CHAPTER - 6 ANATOMY OF FLOWERING PLANTS Plant Anatomy is the branch of Biology which deals with the study of tissues and internal structure of plants. Cells are the basic structural units of a plant. Cells organized into tissues and tissues into organs. I. Simple tissues They are made up of one type of cells. They are with common origin and a common function . They are classified into Parenchyma, Collenchyma and Sclerenchyma. (i) Parenchyma • Isodiametric in shape. • They may be spherical oval, round polygonal or elongated in shape. • Cell wall thin—made up of cellulose • Either closely packed or with small inter Complex Tissues • Complex tissue is composed of more than one type of cells working together as a unit for a common function. • cellular spaces. They are two types (1) xylem and (ii) phloem Functions: • II. 1. Xylem Photosynthesis, storage, secretion Xylem functions as the conducting tissue for water and minerals. It also provides mechanical support. It consists of following 4 types of cells. (i) Tracheids (ii) Vessels (iii) Xylem fibers (iv) Xylem Parenchyma (i) Tracheids Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants Be a student in life to learn something new • 329 . They are elongated dead cells with tapering • ends and lignified cell wall. is called xylem parenchyma. Functions: Conduction of water, Mechanical support. (ii) Vessels (Trachea) • The parenchyma associated with xylem • The cells are living and thin walled. • Their walls are made up of cellulose. In angiosperms, the secondary xylem contains They are long, cylindrical tube like struc- radially elongated parenchyma cells called the tures made up of many dead cells called ray parenchyma. It helps in radial conduc- Vessel members. tion of water. • The vessel cell are devoid of protoplasm. • The vessel members are with lignified Functions: wall and large central cavity. The ves- (1) Helps in upward conduction of water. sel (ii) Stores food materials in the form of members are interconnected through perforations in their common wall. The wall area bearing perforation is called perforation plate. • Presence of vessels is a characteristic feature of angiosperms. • starch or fat. Protoxylem and metaxylem The primary xylem is of two types. (i) Protoxylem and (iii) Metaxylem Gymnosperms lack vessels. Functions of vessels: Upward conduction of water , Mechanical Support. (iii) Xylem fibres (wood fibres): • They are sclerenchyma cells associated with xylem. • • They are thick walled , dead, elongated cells with pointed ends. Endarch and Exarch xylem The walls are lignified with reduced lu- Endarch xylem: Protoxylem lies towards the men. centre (pith) and metaxylem towards the periphery. Eg: Stem Function: Mechanical Support. (v) Xylem parenchyma (wood parenchyma): Plus 1 Biology Exarch xylem: Protoxylem lies towards the periphery and metaxylem towards the cen- Winner’s Coaching Centre Anatomy of flowering plants Keep calm and respect others • 330 . tre Eg: Roots III. Epidermis is usually single layered. 2 IV. The epidermis of root is called piliferous layer or epiblema. V. The outside of the epidermis is covered with a waxy thick layer called cuticle. Cuticle is absent in roots. Stomata I. Stomata are minute pores presents in the leaf epidermis. II. TISSUE SYSTEMS shaped cells called guard cells. A Group of tissues performing a similar function is called a tissue system. On the basis of III. IV. tissue systems. Epidermal tissue system. 2. Ground or fundamental tissue system V. 3. Vascular or conducting tissue system. 1. Epidermal tissue system (dermal tissue system) In dicots the guard cell are bean shaped. and VI. In monocots guard cell are dumb –bell shaped. VII. Epidermal cells associated with guard cell body. It is composed of epidermis, stomata and epidermal appendages. are called subsidiary cells (accessory cells). It forms the outer most covering of the plant VIII. Stomatal aperture, guard cells and subsidiary cells are together called stomatal apparatus or stomatal complex. Epidermis It is the outermost layer of the primary plant body. It is formed of elongated, compactly arranged living parenchyma cells. Guard cells bear Chloroplasts and regulate the opening and closing of stomata. 1. II. Outer wall of guard cell is thin and inner wall is thick. structure and location, there are three types of I. Each stoma is guarded by two bean Functions of Stomata • Transpiration • Gaseous exchange Epidermal appendages Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants Learn and share from your heart • 331 . They are of two types • both xylem and phloem are called con- Root hairs: Epidermal hairs on the root are joint vascular bundle. called root hairs. They are unicellular elongation of the epidermal cell. They help to ab- The vascular bundle which consists of • Xylem and phloem occur in the same radius. sorb water and minerals from the soil. Trichomes: Epidermal hairs on the stem are Collateral bundles: When xylem and phlo- called trichomes. em are placed side by side in the same bun- They are multicellular, branched, unbranched, or secretory. dle it is known as collateral. Function: • They help in preventing water phloem facing outside. loss due to transpiration. • Ground Tissue System. • • Collateral bundle may be open or closed. Tissues, excepct epidermis and vascular Open vascular bundle: Vascular bundle with bundles constitute the ground tissue. Cambium in between xylem and phloem in a Consists of parenchyma, Collenchyma vascular bundle, it is called closed. E.g: monocot stems. and sclerenchyma. • In such a bundle xylem is internal and In leaves, ground tissue is composed of thin walled chlorenchyma cells called Concentric bundle: Here one of the vascular mesophyll. component is central in position, while the other surrounds it. The vascular tissue system It consists of a number of vascular bundles. Radial Vascular bundle Each vascular bundle is made up of xylem and In these bundles xylem and phloem groups oc- phloem. cur in the form of separate bundle (xylem Function: Conduction of food and water. bundles and phloem bundles). These two bundle are found in different radii. Vascular Bundles E.g.: roots Vascular bundle is formed of xylem and phloem. There are two types of vascular bundle. (1) Conjoint (2) Radial Conjoint Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants You become what you study • 332 . parenchyma cells with intercellular spaces. Endodermis • The innermost layer of cortex is called the endodermis. • It is composed of a single layer of compactly arranged barrel - shaped living cells. • The radial walls and inner tangential walls of endodermal cells are thickened due to the disposition of water impermeable, waxy material called suberin. • ANATOMY OF DICOTYLEDONOUS AND MONOCOTYLEDONOUS PLANTS 1. DICOTYLEDONOUS ROOT (DICOT ROOT) These thickenings are called the casparian strips (casparian thickenings) Passage cells Some cells of endodermis, especially those opposite to proxylem remain thin walled . Such A thin transverse section (T.S. or C.S) of cells are called passage cells. The passage cells young dicot root show three distinct regions: allow the passage of water from cortical cells to xylem. 1. Epidermis 2. Cortex 3. Stele 3. Stele The central portion of the root is called stele. It consists of pericycle, Vascular bundles, 1. Epidermis Conjunctive tissue and Pith. • It is the outermost layer. Pericycle: A few layers of thick walled par- • It bears unicellular root hairs. enchymatous cells lie inner to the endo- • Stomata and cuticle are absent. dermis. Lateral roots originates from pericycle. 2. Cortex • Vascular cambium originates from pericy- It consists of several layers of thin walled Plus 1 Biology cle. Winner’s Coaching Centre Anatomy of flowering plants Knowledge is the new currency • 333 . Vascular bundles: They are intercellular spaces. • Radial Endodermis: It is the innermost layer of cor- • Bundles two to four in number. • Xylem is exarch. • Xylem vessels are polygonal in shape. tex. Cells are barrel shaped with casparian strips. Passage cells present. 3. Stele Conjunctive tissue: It consists of parenchymatous cells found between xylem and phloem. The stele consists of pericycle, vascular bundle, Conjunctive tissue and pith. (i) Pericycle - single layer, parenchymatous Pith: (ii) Vascular bundles It is small or inconspicuous. • Radial • Xylem is exarch • More than six bundles (polyarchy) • Xylem vessels are round in shape (iii) Conjunctive tissue - Parenchymatous cells found between xylem and phloem (iv) Pith - Large and parenchymatous Secondary growth is absent in monocot root Difference between dicot root and monocot root 2. Monocotyledonous root (monocot root) 1. Epidermis Composed of single layer of cells without cuticle. Root hairs present. 2. Cortex Consists of parenchymatous cells with large Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants Be stronger than your excuses • 334 . DICOT ROOT 3. DICOTYLEDONOUS STEM (Dicot Stem) MONOCOT ROOT 1. Xylem and phlo- 1. Xylem and phloem groups are lim- em groups are nuited in number (2 merous in number A transverse section (T.S) of young dicot stem shows 3 distinct regions - Epidermis, cortex and stele. to 6 ) diarch to hex- (polyarchy). Epidermis arch • The outermost protective layer of the di- 2. Xylem cells are 2. Xylem cells are cot stem is called epidermis. It consists polygonal in shape. rounded in shape. of a single layer of cells. 3. Pith is reduced 3. pith is large and • It bears cuticle, trichomes and a few stomata. or absent. well developed . 4.Secondary 4.Secondary Cortex growth is present growth is absent. It is the region between epidermis and stele. It is differentiated into following three zones. (i) Hypodermis It consists of a few layers of Collenchyma below the epidermis. It provides mechanical support. (ii) General cortex Consists of round, thin walled, parenchyma cells with intercellular spaces. (iii) Endodermis It is the innermost layer of cortex. The cells are with starch grains. Stele It is the central part of the stem inner to the endodermis. It consists of Pericycle, vascular bundles, medullary rays and pith, (1) Plus 1 Biology Pericycle: It is multilayered and scleren- Winner’s Coaching Centre Anatomy of flowering plants Wake up with determination and go to bed with satisfaction • 335 . chymatous. It is found as semilunar patches inner to endodermis and above the phloem and forms a bundle cap (2) Vascular bundles: It is composed of xylem, phloem and cambium. Vascular bundles possess following characters. • Limited in number • Arranged in a ring • Conjoint—xylem and phloem in the same bundle • Collateral - Xylem and phloem in the same radius • 4. MONOCOTYLEDONOUS STEM and phloem. • Endarch xylem - A transverse section (T.S) of monocot stem protoxylem lies to- wards the Centre • (Monocot Stem) Open - cambium present between xylem shows the following parts epidermis, ground tissue, and vascular bundles. 1. Epidermis Xylem vessels are polygonal Single layer of parenchyma cells. Cuticle and (3) Medullary rays (pith rays) stomata are present. Hairs are absent. The radially elongated parenchyma cells present between two adjacent vascular bundles 2. Ground tissue radiating from the pith is called a medullary It is the mass of cells inside the epidermis ex- rays. cept vascular bundles. (4) Pith (Medulla) It is not differentiated. It is made up of paren- The central part of the stele is known as pith. chyma with intercellular spaces. It is very large and made up of parenchyma The region just below the epidermis is called with hypodermis. It is made up of sclerenchyma. intercellular spaces. 3. Vascular bundles It is composed of xylem and phloem. Vascular bundles possess following characteristics. Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants You are more than who you were • 336 . • They are numerous and scattered in the ground tissue • They are smaller and more numerous towards the outside. They are larger and more spaced towards the centre • Rounded or oval in shape • Conjoint and collateral . • Closed (Cambium absent between xylem and phloem) • Surrounded by sheath of sclerenchyma known as bundle sheath. • Xylem is endarch (protoxylem points towards the Centre) • Xylem Vessels are oval or round in shape. • Phloem parenchyma is absent. Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants You are more than who you were • 337 . Difference between dicot and monocot leaf) shows 3 distinct regions.—Epidermis, stem mesophyll Dicot stem Monocot stem 1. Ground tissue is 1. Undifferentiat- differentiated ed into cortex, en- tissue. dodermis, pericycle, stele and pith. 2. Vascular bundles are limited in number and are arranged in a ring . 3. Vascular bundles are open 4. Collenchymatous hypodermis 5. Sclerenchymatous bundle cap is present 6. Bundle sheath is absent. 7. Protoxylem lacuna is absent. 8. Secondary growth is pre- vascular bundles. ground 2. Vascular bun- dles are numerous and scat- 1. Epidermis • Upper and lower epidermis are covered with cuticle. tered. 3. Vascular bun- • mis (adaxial epidermis) 4. Sclerenchymatous hypodermis. The lower epidermis (abaxial epidermis) bears more stomata than upper epider- dles are closed. 2. Mesophyll The tissue between the upper and lower epider- 5. Bundle cap is mis is called mesophyll. The cells carry chloroplast. absent. 6. Sclerenchyma- • Mesophyll is differentiated in to upper tous bundle palisade parenchyma and lower spongy sheath is pre- parenchyma. sent . (1) Palisade parenchyma - They are adaxially placed, made up of elongated cells, 7. Protoxylem lacuna is pre- arranged vertically and parallel to sent. each other. (i) Spongy parenchyma - Oval or round 8. Secondary growth is ab- loosely arranged cells with large intercellu- sent. lar spaces. sent. These cells lie towards the lower epidermis. 1. DICOT OF LEAF (Dorsiventral leaf) 3. A cross section of a dorsiventral leaf (dicot • Plus 1 Biology and Vascular bundles They are found in veins and midrib Winner’s Coaching Centre Anatomy of flowering plants Every problem born with solutions • 338 . They are surrounded by a layer of paren- • Each bundle is covered by parenchyma- • chymatous bundle sheath. tous bundle sheath. Vascular bundles are Collateral and • closed. These are large empty colorless cells • Xylem on the upper side and phloem on • the lower side. • 2. Bulliform cells (Motor cells) found in the adaxial epidermis in grasses. When the bulliform cells in the leaves • The protoxylem is turned to the upper have absorbed water, they are turgid. As epidermis. a result, leaf surface is exposed. MONOCOT LEAF (Isobilateral leaf) Due to the water stress bulliform cells • become flaccid. As a result, they make A cross section of monocot leaf shows three the leaves curl inwards to minimize the regions epidermis, mesophyll and vascular water loss. bundle. Difference between dorsiventral leaf (dicot leaf) and isobilateral leaf (monocot leaf) Dorsiventral leaf Isobilateral (dicot leaf) leaf (monocot leaf) 1. Cuticle thick at 1. Uniform cuticle upper epidermis on both surface. Epidermis - Upper and lower epidermis are coated with cuticle . Stomata are present on both the epidermis. The upper epidermis. The upper epidermis contains special bulliform cells. are 2. Equal number of more on lower stomata on either surface. side. 3. Mesophyll is dif- 3. Mesophyll is not Mesophyll—It is not differentiated into palisade and spongy tissue. ferentiated palisade into paren- chyma and spon- Vascular bundles: They are collateral, closed and endarch type. • 2. Stomata gy parenchyma. 4. Bulliform Xylem occurs towards the upper side and differentiated. 4. Bulliform cells are present in upper epidermis. cells are absent in the phloem towards the lower side. Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants Success comes with number of people you help • 339 . IMPORTANT QUESTIONS b) Veins from a network. 1. Stem grows in girth due to ……… c) Mesophyll is well differentiated into 2. Closed vascular bundles lack……. 3. Outermost layer of stele is called …… 4. Epiblema of roots is equivalent to palisade and spongy parenchyma. d) Mesophyll is not differentiated into palisade and spongy parenchyma. 10. a) Pericycle ing of the leaf surface? b) Endodermis (a) Bulliform cells c) Epidermis (c) Palisade parenchyma d) Stele (d) Bundle sheath cells. 5. Complex tissues are found in higher plant tissues, found in gymnosperms from the hints provided below: overcome water stress? 12. Choose the appropriate terms given below and arrange them correctly in the table Xylem tracheids, Xylem vessels, sieve provided. tubes, albuminous cells, sieve cells, com Casparian strips, Starch sheath, poly panion cells, xylem parenchyma. archy xylem, closed vascular bundles, Differentiate exarch and endarch arrange- bundle sheath, bundle cap, spongy paren ment of primary xylem. 7. (b) Xylem tissue 11. How does bulliform cells help grasses to groups, Choose the components of complex 6. Which of the following helps in the curl- chyma. Epidermal hairs are found in root and stem. Monocot stem Dicot stem Monocot root (a) Name the epidermal hairs in stem. (b) Write any two functions of stem. 8. 9. A conjoint and open vascular bundle will 13. In the early morning, droplets of water be observed in the transverse section of can be found at the tips of grass leaves. …... Name the phenomenon. Can you give an explanation for this phenomenon? In a monocot leaf a) Bulliform cells are absent from the epidermis Plus 1 Winner’s Coaching Centre Anatomy of flowering plants We rise by lifting others • 340 . PREVIOUS YEARS QUESTIONS and write the structures seen in epider mal tissue system. Write their functions. 14. Choose the correct answer. 19. The following are the anatomical features Casparian strips are present in of flowering plants. Arrange these fea- (a) Dicot root (b) Dicot stem tures in the table given below: (c) Dicot leaf (d) Monocot stem i) Exarch xylem ii) Presence of hypodermis 15. Observe figure given below: iii) Palisade parenchyma cells iv) Conjoint and open vascular bundles v) Endodermis with casparian strips vi) Large empty bulliform cells Write any three features on mesophyll Stem cells from the figure. . Root Leaf 16. Arrange the following anatomical characters in appropriate column. Conjoint vascular bundle, Upper and lower epidermis, Exarch xylem, Radial vascular bundles, Endarch 20. Complete the flow chart given below: xylem, Ground tissue is called mesophyll. 17. Some functions of various tissues in plants are given below. Identify the tissue. a) Conduction of water b) Provides support to the growing parts of the plant c) 18. Storage 21. The tissue found between the upper and Observe the terms given below: lower epidermis of a leaf called meso- Xylem, Root hairs, Pith, Stomata, Cam bium, Bulliform cells. From this identify Plus 1 Biology phyll (a) Write the type of cells found in this Winner’s Coaching Centre Anatomy of flowering plants Helping others is the way we help ourself • 341 . tissue in a dicot leaf. and replace the outer broken cortical and epidermal layers? (b) Mention two differences between a dicot leaf and monocot leaf. 26. The internal anatomy of dicot and monocot stems shows many differences. Men- 22. Choose the correct answer? tion any four differences between their All tissues on the inner side of the endo vascular bundles. dermis together constitute. a) Conjunctive tissue c) Pericycle b) Stele d) Vascular bundle ANSWERS 1. Vascular cambium ,lateral meristem below: 2. Cambium Identify the plant part and explain any 3. Pericycle two features of its vascular bundles. 4. Epidermis 5. Xylem tracheids, albuminous cells, sieve 23. Observe the T.S. of a plant part given cells, xylem parenchyma. 6. Endarch xylem - Protoxylem lies towards pith and protoxylem towards periphery. Exarch xylem - Metaxylem lies towards pith and protoxylem towards periphery. 7. b) Secretory, prevent water loss due to 24. The following are the characters of and monocot stems. a) Trichomes transpiration. Identify the characters and write in appropriate column: 8. Dicot stem. a) Sclerenchymatous hypodermis 9. Mesophyll is not differentiated into palisade and spongy parenchyma. b) Collenchymatous hypodermis c) Vascular bundles are conjoint, closed d) Vascular bundles are arranged in a ring. 10. Bulliform cells 11. Bulliform cells absorb water and become turgid and the leaf surface exposed. When they become flaccid due to water 25. How does periderm develop in dicot stem Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants If you can dream it, you can do it • 342 . stress, leaves curl inwards and minimize water loss. 12. 17. a) Xylem b) Collenchyma Parenchyma Monocot stem Dicot stem Monocot root c) Closed vascular bundles, bundle sheath Starch sheath, bundle cap Polyarch xylem, casparian strips. 18. Root hair - Absorption of water and minerals. Stomata - Transpiration and gaseous exchange. Bulliform cells - Rolling and unrolling 13. Guttation of leaves to reduce surface area; when It is the loss of water in the form of drop turgid they expose leaf surface and when lets from the vein ending of the leaf. flaccid curls. 19. 14. a) Dicot root 15. 1) Divided into palisade and spongy pa- renchyma. 2) Spongy parenchyma loosely packed with air cavities. 3) Palisade parenchyma contains more chloroplast. Stem Root Leaf Conjoint and Exarch xyopen vascu- lem lar bundles Presence of hypodermis Palisade parenchyma cells. Endodermis Large empty with caspari- bulliform an strips. cells 16. Stem Root 1. Con- 1. Exarch joint vas- xylem cular 2. Endarch xylem 20. Leaf 1. Upper and lower epidermis 2. Radial 2. Ground vascular bun- tissue is dles called meso- . Plus 1 Biology Winner’s Coaching Centre Anatomy of flowering plants The enlightened minds can't be dark • 343 . 21. (a) Palisade parenchyma and spongy parenchyma. 25. • (b) Monocot Leaf 1. Isobilateral tissue cork cambium or phellogen develops in the cortex. Dicot Leaf 1. Dorsiventral 2. Stomata equally 2. Stomata usually present on both sur- present on lower faces surface. 3. Stomata have dumbbell shaped Meristematic • Phellogen cuts off cells on both sides. • The outer cells differentiate into suberized cork or phellem. • chymatous secondary cortex or phello- 3. Stomata have bean shaped guard derm. • 4. Mesophyll is un- 4. Mesophyll is difdifferentiated ferentiated into palisade and spongy The inner cells differentiated into paren- Phellogen, phellem and phelloderm are collectively known as periderm. • At certain region, the phellogen cuts off closely arranged parenchymatous cells 5. Bulliform cells are present. 22. (b) Stele 23. Dicot stem 5. Bulliform cells are absent. called lenticels. 26. Dicot stem Vascular bundles are arranged in the form of ring. Vascular bundles open, conjoint. Endarch xylem 24. Dicot stem Monocot stem 1. Collenchymatous hypodermis. 1. Sclerenchymatous hypodermis. 2. Vascular bundles. 2. Vascular bundles ar conjoint, closed. Plus 1 Biology on outer side with lens shaped opening Monocot stem 1. Ground tissue 1. Ground tissue is differentiated is not diffentiated. into cortex, endodermis, pericycle and pith. 2. Vascular bundles are arranged in a ring. 2. Vascular bundles are scattered. 3. Vascular bundles are open without bundle. 3. Vascular bundles are closed surrounded by sclerenchymatous bundle sheath. 4. Secondary growth present. 4. Secondary growth absent. Winner’s Coaching Centre Anatomy of flowering plants Knowledge is the new currency • 344 . CHAPTER - 7 STRUCTURAL ORGANISATION IN ANIMALS FROG active state till favourable conditions return. Morphology Skin is moist, smooth and slippery due to the presence of mucus. Dorsal side of the body is olive green with dark, irregular spots. colour. The most common species of frog found in India is Rana tigrina. They are am- phibious i.e. they can live both on land in water. so they do not have a constant body temperature. A membranous tympanum is present on either side of the eyes to receive sound They show the phenomenon of camou- signals. flage, i.e., they have the ability to change the colour of their skin to sit the Bulging eyes are protected by a nictitating membrane that protects them while with the temperature of the environment, A pair of nostrils is present above the mouth. They are poikilothermic or Cold blooded, i.e. their body temperature varies Body is divisible into head and trunk. Neck and tail are absent. and in freshwater. They belong to class Amphibia of phylum Chordata. Ventral side of the body is pale yellow in Fore limbs and hind limbs are used for colour of the surroundings. swimming, walking, jumping, leaping They exhibit aestivation or summer and burrowing. sleep during peak summer and hiberna- Hind limbs end in five digits and they are tion or winter sleep during peak winter. larger and muscular than fore limbs During this period they take shelter in which end in four digits. deep burrows to protect them from extreme heat and cold and remain in an inPlus I Biology Feet have webbed digits that help in swimming. Winner’s Coaching Centre Structural Organisation Nothing can stop you now • 345 . Frogs exhibit sexual dimorphism. Males into the stomach which in turn continues have sound producing vocal as the intestine, rectum and finally opens sacs and also copulatory pads on the outside by the cloaca. first digit of the fore limbs which are absent in females. Pancreas, a digestive gland produces pancreatic juice Anatomy Liver secretes bile that is stored in the gall bladder. Frogs absorb water through the skin; they never drink water. Oesophagus is a short tube that opens containing digestive enzymes. The body cavity of frogs accommodate different organ systems like, digestive, Food is captured by the bilobed tongue. circulatory, respiratory, nervous, excreto- Digestion and absorption ry and reproductive systems with well Digestion of food takes place by the developed structures and functions. action of HCI and gastric juices secret- 1. Digestive system ed from the walls of the stomach. Consists of alimentary canal and diges- passed from stomach to the first part of tive glands. the intestine, the duodenum. Alimentary canal is short because frog are carnivores; so length of the intestine Duodenum receives bile from gall bladder and pancreatic juice from the pan- is reduced. Partially digested food called chyme, is creas through a common bile duct. Mouth opens into the buccal cavity that leads to the esophagus through Pharynx. Bile emulsifies fat and pancreatic juices digest carbohydrates and proteins. Final digestion takes place in the intestine. Diested food is absorbed by the numerous finger—like folds in the inner wall of intestine called villi and microvilli. The undigested solid waste moves into the rectum and passes out through cloaca. Plus I Biology Winner’s Coaching Centre Structural Organisation The enlightened minds can't be dark • 346 . 2. Respiratory system Frogs respire on land and in the water by • two different methods, in water, skin acts brane called pericardium. • as aquatic respiratory organ (cutaneous respiration). Dissolved oxygen in the water is exchanged through the skin by • On land, the buccal cavity, skin and lings Respiration by lings is called pulmo- nus arteriosus on the ventral side of the • Comprises of arteries and veins. Arteries: They carry oxygenated blood from of elongated, pink coloured sac - like heart to all parts of the body (arterial system). structures present in the upper part of the Veins: They collect deoxygenated blood from trunk region (thorax). different parts of the body to the heart (Venous Air enters through the nostrils into the system). During aestivation and hibernation, gas exchange takes place through skin. 3. Blood vessels nary respiration. The lungs are a pair buccal cavity and then to lungs. The ventricles opens into a sac—like Coheart. act as respiratory organs. A triangular structure known as sinus venosus joins the right atrium. diffusion. It is covered by a double layered mem- Circulatory system Circulatory system consists of (A) Blood vascular system Portal system: This system consists of veins and their capillaries that collect deoxygenated blood from a major organ and empty it into some other organ through capillaries, instead of pouring its contents into the right auricle through a larger vein. This system begins and ends in capillaries in the liver or kidney. (A) Blood vascular system Hepatic portal system: • It is of the closed type harmful nitrogenous wastes are purified and • Consists of heart, blood vessels and glucose gets converted to glycogen. blood. Renal portal system: This system collects blood from the intestine to the liver. Where blood from the lower parts of the body and Heart • Heart is muscular structure situated in the upper part of the body cavity. • this system carries kidney. Blood reaches the heart through the kidneys where urea and uric acid present in blood are filtered. It is three chambered, with two auricles (atria) and one ventricle. Plus I Biology Winner’s Coaching Centre Structural Organisation There is no substitute for hard work • 347 . Blood • orly in the body cavity on either side of puscles. RBC (Red Blood cells) or or leucocytes and platelets or thrombo- niferous tubules or nephorns. the kidneys. The ureters act as urino- coloured respiratory pigment haemoglo- genital ducts which open into the cloaca. Blood transports nutrients, gases, water circulation. open separately in the cloaca. The muscular heart (myogenic )pumps Consists of lymph, lymph channels and excreted. It is filtered out from the blood capillar5. It is different from blood. It lacks a few proteins and RBCs. Control and coordination The system for control and coordination is well—developed in frog and involves both nervous system and endocrine system. 4. Excretory system Frog has a well—developed excretory system to eliminate nitrogenous wastes from the body. Neural system Neural system in frog is highly evolved and organized into a central nervous The excretory system consists of a pair of kidneys, ureters, cloacea and urinarybladder. Excretory wastes are carried by blood into the kidney where it is separated and ies in the form of a colorless fluid. Nitrogenous waste is excreted in the form of urea, so frog is ureotelic. lymph nodes. • A thin walled urinary bladder is present into the cloaca. (B) Lymphatic system • In female frogs, the ureters and oviduct ventral to the rectum which also opens blood to the different parts of the body. • In male frogs, two ureters emerge from RBC’s are nucleated and contain the red and wastes to the respective sites during • Each kidney is composed of several structural and functional units called uri- bin. • erythrocytes, WBC (White Blood Cell) cytes form the blood cells. • the vertebral column. Composed of plasma and cells or cor- system (brain and spinal cord), a peripheral nervous system (cranial and spinal nerves) and an autonomous nervous system (sympathetic and parasympa- Kidneys are compact, dark red, bean thetic. ) shaped structures situated a little posteriPlus I Biology Winner’s Coaching Centre Structural Organisation Be so good, they can't ignore you • 348 . There are 10 pairs of cranial nerves (nerves arising from the brain). 6. Endocrine system Brain is enclosed within the cranium of organs of the body is carried out by hor- the skull. It is divided into fore—brain, mones secreted by the endocrine glands mid –brain and hind—brain. (ductless glands). Fore - brain is represented by a pair of rold, thymus, pineal body, pancreatic Hind - brain consists of cerebellum islets, adrenals and gonads. and medulla oblongata, which extends into the spinal cord enclosed within the Endocrine glands are ductless glands and vertebral column; after passing out their secretions are called hormones; through the foramen magnum. which are released directly into the blood stream. Sense organs The prominent endocrine glands found in frog are pitultary, thyroid, parathy- optic lobes. The chemical coordination of various Frog has all 5 types of sense organs. 7. Reproductive system Sexes are separate in frog. They have They are the following. well organized male and female reproductive Organs of touch - Sensory papillae Organs of taste - taste buds. Organs of smell - nasal epithelium Organs of vision - eyes sist of a pair of ovoid, yellowish testes, Organs of hearing - tympanum with which are found attached to the upper systems. They show sexual dimorphism. Male reproductive system Male reproductive organs: They con- part of kidneys by a double fold of peri- internal ear toneum called mesorchium. Eyes (simple eyes) are a pair of spherical structures situated in the orbit in the Vasa efferentia arising from testes are 10 - 12 in number, they enter the kidneys skull. on their side and open into Bidder’s ca External ear is absent. Only the tympa- nal. num is visible externally. Finally it communicates with urinogeni- Ear is an organ of hearing and equlibri- tal duct that comes out of the kidneys uim (balancing). and opens into the cloaca. Plus I Biology Cloaca is a small, median chamber that is Winner’s Coaching Centre Structural Organisation Whatever you are, be a good one • 349 . used to pass faecal matter, urine and sperms to the outside. Female reproductive system This includes a pair of ovaries. They are situated near the kidneys but there is no functional connection with them. A pair of oviducts arise from the ovaries and open into the cloaca separately. A mature female lays 2500 - 3000 ova at a time. Fertilization and development Fertilization is external and takes place in water. Development is indirect and involves a larval stage called tadpole. Tadpole undergoes metamorphosis to form the adult. Economic Importance Frogs are harmless and beneficial to mankind. They eat insects and thus protect crops. Frogs serve as an important link in the food chain and food web, so they help to maintain ecological balance in the ecosystem. IMPORTANT QUESTIONS 1. Frog show sexual dimorphism. a) Write the morphological differences present only in male frogs. The muscular legs of frogs are used as food by man in some countries. Plus I Biology Winner’s Coaching Centre Structural Organisation Nothing can dim the light that shines within you • 350 . 2. a) Identify the diagram . 5. In frog, the toes are inter—connected by skin. b) Label the numbered parts. a) What is it called ? b) What is its function ? 6.A frog with body temperature 23.50 C is transferred to an area having 25 0 C temperature. What will be the body temperature of this frog in the new environment ? Substantiate your answer. 7. Complete the table. Animal Excretory Respiratory organ Organ ……. ……… Frog 3. Differentiate aestivation from hibernation? 4. Name the labelled parts a, b, c and d in the diagram given below. 8. Mention the function of the following. 1. Ureters in frog. 9. Regarding the blood - vascular system of frog, some statements are given below. Check whether these are true or false and make corrections if necessary. a) Open type b) Sinus venosus joins the right ventricle c) RBC is non– nucleated d) Circulation is achieved by the pumping action of the heart. Plus I Biology Winner’s Coaching Centre Structural Organisation Education is the key to success • 351 . ANSWERS 8. 1. Passage of urine (urea) and sperms 1. a) 1. Presence of vocal sacs 2. Presence of copulatory pad on the 1 st digit of 9. a) False b) False - Closed type - Sinus venosus joins the right atrium the forelimb. 2. a) Male reproduction system and excretory system of frog. b) 1 - Fat body c) False - Nucleated d) True 2 - Testis , 3 - Kidney , 4 - Rectum , 5 - Urinary bladder. 3. Aestivation - summer sleep Hibernation - winter sleep 4. a - Liver, b - Pancreas, c - Rectum, d - Urinary bladder 5. a) Web b) It helps in swimming 6. The body temperature of frog in the new environment will be 250C. Because , frogs do not have constant body temperature. So , they are poikilotherms ( cold blooded animals) with their body temperature changing with surrounding temperature changes. 7. Animal Frog Plus I Biology Excretory Respiratory organ organ Kidney Lungs and skin Winner’s Coaching Centre Structural Organisation Hard work beats talent when talent doesn't work • 352 . CHAPTER 8 CELL:THE UNIT OF LIFE What is a cell? The cell is the basic structural and functional unit of life. Cell theory i. The cell theory was formulated first by two biologists, M.J. Schleiden and Theodore Schwann. ii. They proposed the hypothesis that the bodies of animals and plants are composed of cells and products of cells. prokaryotic cells lacking a membrane- bound nucleus and organelles. CYTOPLASM Is the semifluid matrix of the cell which is the main area of cellular activities that keep the cell in the living state. Membrane bounded cell organelles are: ENDOPLASMIC RETICULUM (ER): It consists of an intercommunicating system of channels made of membranous sacs iii. Rudolf Virchow first explained that cells divide and new cells are formed from preexisting cells. AN OVERVIEW OF CELL CELL WALL • It is the outer boundary of plant cell. Cell membrane is present inside it. • Cell membrane is the outer boundary of animal cell. NUCLEUS • The principal organelle of the cell. • It is a membrane bound structure that contains chromosomes which in turn contains the genetic material DNA. a) Rough ER (RER): It bears ribosomes on its membrane surface. It is involved in protein synthesis and secretion. b) Smooth ER (SER): It is free from ribosome and synthesis lipids EUKARYOTE GOLGI COMPLEX Eukaryotes are distinguished by the fact that their cells possess a membrane – bound nucleus containing the genetic material. • Consists of stacks of flat, membranous cisternae. Eg. Amoeba, Angiosperms. • It helps to concentrate secretory materials and packs them into secretory vesicles PROKARYOTE An organism that is either a bacterium or a blue- green algae, its main characteristic being Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Value yourself to fight for happiness • 353 . A Cavity in the cytoplasm containing an aqueous solution and bound by a unit membrane. Non – membrane-bound organelles are: RIBOSOMES These are granular organelles and are not enclosed by any membrane. Found in both Eukaryotic and prokaryotic. Within the cell, ribosomes are found not only in the cytoplasm, but also within the two organelles – chloroplasts (in plants) and mitochondria and on rough ER. LYSOSOMES • They are termed the ‘suicidal bags’ of the cell. • They store acid hydrolases in their fluid content. • They fuse with damaged organelles and hydrolyse them. CENTRIOLE Animal cells contain another nonmembrane bound organelle called centriole which helps in cell division. Cells differ greatly in size, shape and activities. PROKARYOTIC CELLS • They are primitive. They do not contain a true nucleus and membrane-bound cell organelles. • They have a cell wall, surrounding the cell membrane. MITOCHONDRIA • No well-defined nucleus. The power house of a cell. • In addition to genomic DNA, many bacteria have smaller circular DNA called plasmid, are present. • Specialized form of cell membrane called mesosomes are present. • Ribosomes and other inclusions are scattered in the cytoplasm MICROBODIES • Prokaryotic cells are represented by bacteria and blue-green algae, mycoplasma and PPLO (pleuro pneumonia like organisms.) Many membrane- bound minute vesicles. There are four basic shapes of bacteria:- VACUOLES * Plus I Biology Bacillus Winner’s Coaching Centre Cell: The Unit Of Life Think like a proton, always positive • 354 . Coccus Vibrio MESOSOMES Spirillum • A Special membranous structure which is formed by the extensions of the plasma membrane into the cell in bacteria are called mesosome. into and out of the cell. PLASMID A Circular piece of DNA found in the cytoplasm of bacterial cells that replicates independently of the host chromosome. The plasmids can be important in public health since some types possess genes for antibiotic resistance, and can be quickly transferred to different types of host cells, thus spreading resistance very rapidly. Plasmids are used extensively in genetic engineering of microorganisms. CELL ENVELOPE AND ITS MODIFICATIONS It is the outermost layer. Some have a loose sheath around the outermost layer, known as slime layer. This slime layer protects the cells from loss of water and nutrients. Sometimes in some others, this layer is covered with a thick and tough covering. This is known as capsule. This capsule is essential for the survival of the cell. CELL WALL It is seen below the glycocalyx. This layer is rigid due to the presence of peptidoglycan. PLASMA MEMBRANE • It is the innermost layer of the cell envelope. • It is semipermeable in nature. • It controls the flow of specific molecules Plus I Biology • They also help in respiration, secretion processes and increase surface area of plasma membrane and enzyme action. • In some prokaryotes like cyanobacteria there are certain membranous extensions into the cytoplasm called chromophores. • Flagella: filamentous extensions from the cell wall which help in locomotion (eg: bacteria.) GLYCOCALYX • These are in the form of vesicles, tubules and lamellae that help cell wall formation, DNA replication and distribution into daughter cells. • Bacterial flagellum is composed of three parts – filament, hook, and basal body. • Pili elongated tubular structures from the surface of bacterium. • Fimbriae: There are small bristle like fibres sprouting out of the cell in bacteria. GRAM STAINING • Gram staining is a special technique which is used to classify bacteria. • This technique was developed by Christian Gram in 1884. Procedure • Firstly, bacteria are treated with weak alkaline solution of crystal violet or gentian violet. • The stained bacteria are again treated with 0.5% iodine solution. Winner’s Coaching Centre Cell: The Unit Of Life Today a reader, Tomorrow a leader • 355 . • This is followed by washing with water and alcohol or acetone. • Extensive compartmentalization of cytoplasm • After these procedures, some bacteria retain the purple color, while some others lose it and are colorless. • Presence of membrane-bound organelles. • Those having purple color are known as Gram positive bacteria and those that do not have color are known as gram negative bacteria. • Presence of organized nucleus with a nuclear envelope Plant cell RIBOSOMES AND INCLUSION BODIES RIBOSOMES • Ribosomes are the sites of protein synthesis. • In prokaryotes 70S ribosomes are present. It is made up of 50S and 30S sub units. POLYRIBOSOME OR POLYSOME: Several ribosomes may attach to a single mRNA and form a chain called polyribosomes or polysome. INCLUSION BODIES Animal cell STORAGE GRANULES The reserve material seen in prokaryotic cytoplasm is known as storage granule. They are not bound by any membrane system and lie free in the cytoplasm. Different types of storage granules • Phosphate granules • Cyanophycean granules • Glycogen granules • Gas vacuole • Volutin granules • Sulphur granules EUKARYOTIC CELLS Models of plasma membrane • Eukaryotes include all the protists, plants, animals and fungi There are two models of plasma membrane. They are Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life To lose patience is to lose battle • 356 . i. Unit membrane model The extrinsic proteins are arranged on the surface and are loosely bound to the lipid The intrinsic proteins are partially or totally burried in the lipid bilayer. This model of cell membrane is also called 'protein icebergs in a sea of lipids." ii. Fluid mosaic model Unit membrane model Studies shows that the chemical composition of plasma membrane is variable with lipids, proteins and oligosaccharides. Lipid is the main component in it. Cell wall There are small globular proteins that lie within the lipid bilayer Do all cells have cell wall? Fluid Mosaic model • Only plant cells possess a cell wall. • It provides fixed shape and size to the plant cell. • There is a pectin layer that attaches two adjacent plant cells. This layer is known as middle lamella. Structure of cell wall This model was proposed by S.J. Singer and G.L. Nicholson in 1972 There is a lipid bilayer intermingled with proteins This shows a kind of mosaic arrangement The lipid bilayer is composed of phospholipids Each phospholipid has a polar head and two nonpolar tails. The polar heads are hydrophilic (waterloving) and non-polar tails are hydrophobic (water-hating). The proteins are of two types; extrinsic and intrinsic or integral. Plus I Biology The cell wall consists of three distinct layers. They are, (1) Primary wall (2) Secondary wall (3) Middle lamella 1. Primary wall • This layer consists of a network of micro fibrils. Winner’s Coaching Centre Cell: The Unit Of Life Dream bigger Grow bigger • 357 . • It is formed of cellulose, hemicellulose, pectin and proteins. It is living and can grow. 2. Secondary wall • It is made up of cellulose fibrils. • Sometimes hemicellulose, pectin and lignin are also deposited in it. • The Golgi complex consists of a system of mem brane-bound vesicles of varying sizes arranged in parallel arrays. • In most cells it consists of one or more stacks of flat, expanded intercommunicating, cisternae. • Cisterna is a fluid-filled lumen enclosed by a single smooth membrane. 3. Middle lamella • Golgi apparatus It is a cementing layer between adjacent primary walls and is formed of calcium and magnesium pectate. • Small vesicles of varying sizes are found associated with the cisternae. • Cisternae are usually stacked in parallel rows. They exist as an extensive network near the nucleus. Plasmodesmata The cells are interconnected by cytoplasmic bridges. These bridges are known as plasmodesmata. They help in maintaining continuity of living matter, and the cytoplasm in such condition is called symplasm. The Endoplasmic reticulum (ER) • It is a single membrane-bound cell organelle. • It is involved in active secretion. • The ER bearing ribosomes on their surface is called rough endoplasmic reticulum (RER). • In the absence of ribosomes they appear smooth and are called smooth endoplasmic reticulum (SER). Functions of ER • Mechanical support • Synthesis of secretory (serum proteins), lysosomal or membrane proteins on the ER membrane and its transport through ER lumen. • In plants, the stacks are also called dictyosomes. Lysosomes • Suicidal bag of the cell. • Bound by a single membrane. • Lysosome contains hydrolytic enzymes (hydrolases). • They are formed by the budding off of vesicles from Golgi apparatus • It is concerned with intracellular digestion. Vacuoles • They are fluid-filled sacs bound by a single membrane. • The membrane is known as tonoplast. The fluid in them is called cell sap. Vacuoles can be classified into four types. • Synthesis of lipids • Detoxification of drugs Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Knowledge increases by sharing • 358 . Types of vacuole Sap vacuole Functions Stores and concentrates mineral salts and nutrients. Contractile vacu- Takes part in osmoregole ulation and excretion present in animal cell. Food vacuole Helps in digestion Air vacuole Present in prokaryotes; store metabolic gases; helps in buoyancy of • Inside the chloroplast, there is a colorless substance called the stroma. It is the site of dark phase reactions of photosynthesis. • Stroma contains membrane systems consisting of closed, flattened sacs called thylakoids. • The thylakoids are kept one on top of the other like pillar of coins to form structures called grana. It is the site of light phase reactions of photosynthesis. • Grana are connected together by a system of membranes known as intergranal thylakoids. • Chloroplast contains chlorophyll. Mitochondria • Known as power house of the cell. • Mitochondrion is a double membranebound cell organelle and are usually sausage -shaped, spherical, oval, pear-shaped, cylindrical or filamentous. • It has an outer smooth membrane and inner membrane with many infoldings called cristae. Cristae increases surface area. It has many spherical particles attached to it, which acts as ATP synthase. Plastid • Plastids are organelles that are found only in plant cells and in some unicellular organisms like euglenoids. Classification of plastids Based on the contents, pigments and storage materials, plastids are classified into three • The thylakoids are the storehouses of pho tosynthetic pigments and the enzymes for the light reactions of photosynthesis. Leucoplast Chromoplast Chloroplast • They are colorless plastids. • They are colored plastids • They are green plastids containing the • They are • They conpigment present in tain fat solchlorolarge numuble carotphyll. bers in the enoid pigcells of ments. • They are fruits, seeds, This gives found in tubers and the part of the green rhizomes. the plant a parts of the yellow, plant. orange or red color. Structure of Chloroplast • It consists of two membranes, the outer and inner membranes. • The two membranes are separated by a periplastidial space. Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life In teaching others, we teach ourselves • 359 . • An elaborate network of filamentous proteinaceous structures present in the cytoplasm is called cyto-skeleton. Functions of cytoskeleton • Mechanical support • Motility • Maintenance of the shape of the cell. RIBOSOME • They are tiny organelles found in prokary otes and eukaryotes •They are the sites of protein synthesis. • Each ribosome consists of two sub-units, one large and one small. Cilia and Flagella • They are hair-like outgrowths of the cell membrane. • The organelle is made of 11 microtubules (9+2) enclosed by cell membrane. Of these, 9 microtubules are doublets and peripheral in position; 2 microtubules are single and central. Function: Types of ribosomes - 70 S and 80 S • The 70 S ribosomes are found in prokaryotes and 80 S ribosomes occur in the cytoplasm of eukaryotes. Functions of ribosomes ) ER-bound ribosomes synthesize secretory and lysosomal proteins. ) Free ribosomes synthesize non-secretory proteins Cytoskeleton Plus I Biology They help in locomotion, formation of food and water current and elimination of solid particles. Centrosome and Centrioles • Centrosome is an organelle usually containing two cylindrical structures called centrioles. • It is surrounded by amorphous pericentriolar materials. • Triplet of microtubules. Winner’s Coaching Centre Cell: The Unit Of Life Light a lamp for someone, it will brighten your path too • 360 . • The central part of the centriole is proteinaceous and called the hub. Nucleus • Discovered by Robert Brown (1831). • This is a large organelle controlling all the activities of the eukaryotic cells. • Nucleus is covered by two membranes (outer and inner) which form a nuclear envelope. • The outer and inner membranes are separated by a narrow space called the perinuclear space. • Internal matrix is known as nucleoplasm. • The nuclear envelope is interrupted by the presence of small structures called pores. The pores are enclosed by circular structures called annuli. Based on the position of the centromere, the chromosomes can be classified into 4 types> 1. Metacentric • Nucleus contains chromatin reticulum which transforms into chromosomes during cell division. 2. Sub-metacentric 3. Acrocentric 4. Telocentric • Chromatin contains DNA and some basic proteins called histones, and some nonhistone proteins and also RNA. • Every Chromosome essentially has a primary constriction or the centromere on the sides of which disc-shaped structures called kinetochores are present. Functions. Chromosomes contain DNA) DNA is organized into genes which control all the activities of the cell (Nuclear division is the basis of cell multiplication. The nucleolus manufactures ribosomes. Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Enjoy each and every little thing • 361 . Nucleolus (a) Name the scientists. This is a spherical structure seen in the nucleus. The nucleolus is the site of ribosomal RNA (rRNA) synthesis. The nucleoli are larger and more numerous in cells that are actively involved in protein synthesis. (b) Write the two main points in cell theory. [March 2020] 4. Choose the correct answer. Microbodies A structure seen in bacterial cell is…….. • Single membrane-bound organelles (a) Nucleus (b) Lysosome • Associated with oxidation reactions • They are of two types; peroxisomes and glyoxysomes. (c) Plastid (d) Mesosome [March 2019] 5. Observe the figure given below : PREVIOUS YEAR QUESTIONS 1. Choose the correct answer. The organelle known as the power house of the cell is (a) Ribosome (b) Vacuole (c) Mitochondria (d) chloroplast [March 2020] 2. Peculiarities of certain cell organelles are given below: (a) Involved in protein synthesis (b) Made up of many flat, disc shaped sacs or cisternae (c) Bear ribosomes on their surface (d) Rich in hydrolytic enzymes Identify the parts (A) ,(B). Write their func tions. [March 2019] 6. Ribosome are organelles without a membrane found in all cells. Name another organelle devoid of membrane, seen in animal cells. Write its functions. [March 2018] (e) Membrane is absent [March 2020] Copy the table given below and write the above peculiarities in appropriate column. Lysosome Golgi apparatus Ribosome 7. (a) Identify a cell organelle which contains hydrolytic enzymes (b) Rough Endoplasmic Reticulum (RER) and smooth Endoplasmic Reticulum (SER) are morphologically and functionally different. Justify this statement. [March 2017] [March 2020] 3. Cell theory was formulated by two scientists. Plus I Biology 8. Observe the given diagram. Analyze this diagram and explain the structure of plasma membrane. Winner’s Coaching Centre Cell: The Unit Of Life Never give up, never stop learning • 362 . kinds of chromosomes, of this which is metacentric non - satellite chromosome? Justify your answer. [March 2016] 9. (a) Due to the presence of a secondary constriction a knob - like small fragment appears in some chromosome called— — (i) Kinetochore (ii) Histone (iii) Satellite (iv) Chiasmata (b) Classify chromosomes based on the position of centromere. [March 2013] 13. An accepted model of structure of a cell membrane was proposed by singer and Nicolson. (a) Name the model. (b) List two major biomolecules which this membrane is composed of. (c) Mention two important points of this model from the point of view of function. [March 2015] 10. State whether the statements are ‘True’ Or ‘False’, correct the statements by changing the underlined words. (a) Aleuroplasts store Carbohydrates. (b) The centrioles form the basal body of cilia and flagella. (c) Ribosomes are not surrounded by membranes. 14. Observe the given relation and fill the blanks (a) Plumule : Coleoptile Radicle : …………. (b) Starch : Amyloplast (d) RER is the major site for synthesis of lipids. [March 2014] 11. Prokaryotic cells posses a special membranous structure which is formed by the extensions of the plasma membrane in the form of vesicles, tubules and lamellae. Identify this structure and write any one of its functions. Fat : ………. [March 2013] 15. The following is a list of cell organelles: ( Nucleus, endoplasmic reticulum, lysosomes, Chloroplast, golgi complex, mitochondria, ribosome) (a) Identify the organelles with double membrane envelope. [March 2014] 12. The diagrams a,b,c given below show three Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Love your family, the greatest blessing you have • 363 . (b) Mention the functions of these organelles. 1. ………….. [Sep. 2012] 2. …………… [March 2010] 16. (a) Identify the cell organelle found in eukaryotic and prokaryotic cells. 19. Given below are the diagrams of two chromosomes: (b) Justify its presence in both types of cells. (a) Identify the chromosome types (1) and (2) [March 2012] (b) Write the peculiarity of chromosome 17. Match the following : (a) Synthesis of (i) Golgi appastorage and ratus energy (b) Packing and (ii) Mitochondelivary of dria materials (c) Digestion of (iii) Centriole intercellular materials [March 2009] 20. Choose the most appropriate answer and fill in the blanks. (d) Formation of basal body of cilia and flagella (iv) Lysosome Crystal violet is used ………... (i) as dye (ii) for gram staining (iii) as a food additive (iv) as an insecticide (v) Chloroplast [March 2008] [March 2012] 18. Label the marked parts in the given diagram of chloroplast. 21. Bacterial cell envelop is a complex structure. It is made up of various layers. Name the different layers in the bacterial cell envelope. [March 2007] 22. Mitochondria is called power house of cell. Comment. 23. Different Types of chromosomes based on the position of centromere are given below. Classify them with necessary explanation. What is the peculiarity of the chromosome ‘D’? Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Make your parents proud and be happy yourself • 364 . 4. 5. [March 2007] Cell wall and middle lamellae are transversed by (a) Plasmodesmata (b) Primary wall (c) Cytoplasm (d) Cortex Important site for the formation of glycoprotein and glycolipid is (a) Lysosomes Important Questions (b) Golgi apparatus 1. (c) Vacuoles (d) Plastids Schwann proposed a cell theory according to which (a) The leucoplasts that store oils and fats. Amyloplasts Each cell of body posses the same genetic information. (b) Elaioplasts (c) Aleuroplasts (c) Bodies of animals and plants are made up of cells and their products. (d) Glyceroplasts (d) 3. 6. (a) (b) 2. All the activities of the organisms are present in miniature form in every cell of body. A new cell always developed by the division of pre - existing cells. 7. Omnis cellula - e cellula (all cells arise from pre-existing cells). Who gave this concept and modified the cell theory ? (a) Schleiden and Schwann (b) Virchow (c) Robert Brown (d) Leeuwenhoek 8. The cell organelle that is present in cytoplasm as well as other organelle The cells that lack nucleus are : (a) Erythrocytes of many mammals (b) Tube cells of vascular plants (c) Lymphocytes of mammals (d) Both (a) and (b) What is the function of polysome ? (a) Active protein synthesis (b) Formation of multiple copies of same polypeptide (c) Both (a) and (b) (d) None of the above (a) Mitochondria (b) Ribosome (c) Chloroplast Which of the following features is common to prokaryotes and many eukaryotes ? (d) ER (a) Plus I Biology 9. Winner’s Coaching Centre Chromatin material present Cell: The Unit Of Life Be a better listener to be a better speaker • 365 . 10. (b) Cell wall present (c) Nuclear membrane present (d) Membrane bound subcellular organelles present What is tonoplast ? (a) Outer membrane of mitochondria (b) Inner membrane of chloroplast (c) Membrane boundary of the vacuole of plant cells (d) 11. Cell membrane of a plant cell Match the following columns : Column I Name the scientist who proposed fluid mosaic model. (b) Name and explain the two types of proteins in cell membrane. 14. Pili and Fimbriae are surface structures of the bacteria. Write the function of such structures in bacteria. 15. Mention any four functions of cell wall in a eukaryotic cell. 16. Ribosomes are present in the cytoplasm and certain cell organelles of eukaryotic cells. (a) Name two cells organelles which contain ribosomes. (b) How do ribosomes seen in these cell organelles differ from ribosomes each seen in the cytoplasm of eukaryotes. Column II (a) Centriole 1. Infoldings (b) Chlorophyll 2. Thylakoids (c) Cristae 3. Infolding of plasma membrane in pro- (d) Mesosome (a) 4. of Basal body of Previous Year Question Answers 1. 2. 12. Column I (c) Mitochondrion Column II Lysosome Golgi appa- Ribosome Rich in hydrolytic enzymes (d) Made up of Involved in many flat, protein syndisc shaped thesis. Memsacs or cister- brane is abnae (b) sent (a), (e) (a) Lysosomes 1. Protein synthe- (b) Ribosomes 2. Hydrolytic ac- (c) SER 3. Steroid synthe- • All living organisms are composed of cells and product of cells. (d) Centriole 4. Formation • All cells arise from pre-existing cells. 13. of An improved model of structure of cell membrane known as fluid mosaic model was proposed in 1972. Plus I Biology 3. Schleiden and Schwann 4. d) Mesosome 5. (A) Grana/thylakoid (B) Winner’s Coaching Centre Stroma Cell: The Unit Of Life Reading lights up your world • 366 . Grana function: Light reaction/ Photophosphorylation. teins and carbohydrates. • Peripheral proteins lie on the surface of membrane while the integral proteins are partially or totally buried in the membrane. • The quasi fluid nature of lipid enables lateral movement of proteins within the overall bilayer. (any three structural features) Stroma function: Dark reaction/ Biosynthetic phase/ Carbon fixation. 6. Centrioles/ Centrosome/ Diplosome Functions : Cell division, formation of basal body of flagella or cilia, spindle apparatus during cell division. 7. (a) Lysosomes 9. (a) (iii) Satellite (b) (b) Metacentric chromosome The endoplasmic reticulum bearing ribosomes on their surface is called Rough Endoplasmic Reticulum (RER). In the absence of ribosomes they appear smooth and are called Smooth Endoplasmic Reticulum (SER) RER involved in protein synthesis and secretion. They are extensive and continuous with the outer membrane of the nucleus. SER is the major site for synthesis of lipid. In animal cells lipid like steroidal hormones are synthesized in SER. 8. Submetacentric chromosome Acrocentric chromosome Telocentric chromosome 10. 11. • Cell membrane is composed of lipids that are arranged in bilayer. Hydrophobic tails towards the inner part. • Lipid components of the membrane mainly consist of phosphoglycerides. • True (c) True (d) False. SER is the major site for synthesis of lipids. Mesosome 12. Diagram (b). Middle centromere/Two equal arms/ No secondary constriction/ No satellite 13. (a) Fluid mosaic model (b) Lipid, protein, sugar, cholesterol, phospholipid (c) Cell growth, formation of intercellular junction, secretion, endocytosis, cell division, fluid nature of the membrane, passive transport, active transport. Lipids are arranged within the membrane with the polar head towards the outer side. • (b) Cell wall formation, DNA replication, respiration, secretion, increase surface area of plasma membrane. Fluid mosaic model of plasma membrane . • (a) False. Aleuroplasts store proteins. 14. (a) Coleorhiza (b) Elaioplast Cell membrane also possess pro- Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life You will win if you want • 367 . 15. (a) Nucleus, Mitochondria, Chloroplast (b) Nucleus : Controlling centre of all the activities of the cell, RNA synthesis. 22. Mitochondria are the centres of production, storage and distribution of energy for various metabolic activities of cell. 23. (A) Acrocentric chromosome : The centromere is near the end of the chromosome. Mitochondria : Cellular respiration/ production of energy/ power house/ ATP production/ Kreb’s cycle/ Oxidative phosphorylation. Chloroplast : Light Reaction/ photosynthesis/ CO2 reduction/ Dark reaction/ Light absorption. 16. 17. (c) (d) (C) Submetacentric chromosome : The centromere is near the middle of the chromosome. (D) Metacentric chromosome : The centromere is at the middle of the chromosome . Chromosome ‘D’ has both secondary constriction and a satellite. Protein synthesis It is a non-membranous structure. (b) Submetacentric chromosome : The centromere is near the middle of the chromosome. (a) Ribosomes (b) (a) (B) Synthesis and (i) Mitochondria storage of energy Packaging and (ii) Golgi apparatus delivery of materials Digestion of (iii) Lysosome intercellular materials Formation of (iv) Centriole basal body of cilia and flagella 18. 1. Granum 2. Stroma lamella 19. (a) 1. Metacentric (b) 1. Presence of secondary constriction 2. Acrocentric Important Question Answers 1. (c) Bodies of animals and plants are made up of cells and their products . 2. (b) Virchow 3. (b) Ribosome 4. (a) Plasmodesmata 5. (b) Golgi apparatus 6. (b) Elaioplasts 7. (d) Both (a) and (b) 8. (c) Both (a) and (b) 9. (b) Cell wall present 10. (c) Membrane boundary of the vacuole of plant cells. Presence of satellite. Centromere is at the centre 20. (ii) For gram staining 21. Glycocalyx Cell wall and plasma membrane Plus I Biology Winner’s Coaching Centre Cell: The Unit Of Life Don't be same, be better • 368 . 11. damage and infection Column I (3) Helps in cell-to-cell interaction (4) Provides barrier to undesirable macromolecules (a) Mitochondria and chloroplast (b) Cytoplasmic ribosomes are 80S and ribosomes in cell organelles are 70S. Winner’s Coaching Centre Cell: The Unit Of Life Column II (a) Centriole 4. Basal body of cilia & flagella (b) Chlorophyll 2. Thylakoids (c) Cristae 1. Infoldings of mitochondria (d) Mesosome 3. infolding of plasma membrane in prokaryotes 16. 12. Column I Column II (a) Lysosomes 2. Hydrolytic ac- (b) Ribosomes 1. Protein synthe- (c) SER 3. steroid synthe- (d) Centriole 4. Formation 13. of (a) Singer and Nicolson (b) Peripheral proteins and integral proteins Peripheral proteins are arranged on the surface and integral proteins are partially or totally buried in the membrane. 14. 15. In some bacteria, they are known to help (a) Attach the bacteria to rocks in help (b) Attach to the host tissues (1) Gives shape of the cell (2) Protects the cell from mechanical Plus I Biology Keep calm and respect others • 369 . CHAPTER 9 BIOMOLECULES Biomolecules -Chemical compounds found in living organisms. A biomolecule is a molecule that naturally occurs in living organisms. Minerals Minerals are grouped as major and minor based on their amount required by cells. Formation of zwitterion An amino acid in solution can have charged amino group, (NH3+ ) both amino and carboxylic group charged (NH3+ & COO- ) or charged carboxylic group. If both amino group and carboxyl group are charged, it is called Zwitterionic form. The major minerals of the animal body are: Calcium Phosphorus, Sodium, Chlorine, Magnesium, Sulphur. The minor minerals are: Iron, Copper, Cobalt, Manganese, Molybdenum, Zinc, Fluorine, lodine, Selenium. Zwitter ion Lipids Carbohydrates, Lipids, Amino acids, Proteins, Nucleic acids, Hormones, Vitamins etc. They are water-insoluble compounds containing carbon and hydrogen but less oxygen than that found in carbohydrates. They are high energy organic compounds. Amino acids Classification of lipids Organic compounds: Amino acids are organic compounds containing an amino group (-NH2) and carboxyl group (-COOH). Amino acid consists of carbon, hydrogen, an amino group, carboxyl group and a side group designated "R", which distinguishes one amino acid from another. Based on the number of amino and carboxyl groups, amino acids are classified into three. They are: Lipids are classified into three main types, namely: Simple Lipids Compound lipids Derived lipids Fatty acids They are organic acids having hydrocarbon chains (a chain of carbon and hydrogen atoms) that end in a carboxyl group (- COOH). Acidic amino acids eg: Aspartic acid Basic amino acids, eg: Lysine Saturated fatty acids. Neutral amino acids, eg: Valine Unsaturated fatty acids. • A particular property of amino acids is the ionizable nature of –NH2 and -COOH groups. Plus I Biology Fatty acids are of two main types. They are: Saturated fatty acids do not possess double bonds in their carbon chains. Eg: Palmitic acid. Winner’s Coaching Centre Biomolecules Education is the key to success • 370 . Plus I Biology Winner’s Coaching Centre Biomolecules Always have an attitude of gratitude • 371 . CH₂-(CH₂)14-COOH (Palmitic acid) Polysaccharides (carbohydrates) Unsaturated fatty acids possess one or more double bonds in their carbon chains. Lipids Eg: Arachidonic acid. Nucleic acids. Nucleotides Proteins A nucleic acid molecule is a long chain polymer (polynucleotide) composed of monomeric units called nucleotides. Nucleotides are the basic units of nucleic acids. Proteins Proteins are polymeric molecules in which the subunits are monomers of amino acids which are covalently linked to each other by peptide bonds. Each protein is a polymer of amino acids. Amino acids can be classified as essential or non essential amino acids. Each nucleotide consists of a nucleoside and phosphate group. Each nucleoside consists of a sugar molecule and a nitrogen base. Structure of Proteins. The sugar is ribose in the case of RNA (ribonucleic acid) and deoxyribose in the case of DNA (deoxy ribonucleic acid) Each protein possesses a characteristic three dimensional shape. In describing the three-dimensional structure of proteins it usually refers to four, separate levels of organization as given below: DNA and RNA function as genetic materials. Adenine, guanine, cytosine, uracil and thymine are the nitrogen bases. Primary structure Adenosine, guanosine, thymidine, uridine and cytidine are nucleosides. Secondary structure Tertiary structure Adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid are nucleotides. Quarternary structure Biomacromolecules Micro molecules Primary Structure: The primary structure of a protein refers to its unique number and sequence of amino acids linked by peptide bonds in a polypeptide chain. They are small organic molecules that give rise to macromolecules on polymerization. Macromolecules Large organic molecules, characteristic of living organisms. Biomacromolecules of the cell are categorized into four main classes. They are: Plus I Biology Winner’s Coaching Centre Biomolecules Be the light for your family • 372 . Secondary structure: The secondary structure of proteins refers to the spatial arrangement of polypeptide chains as a result of hydrogen bond formation. The − (alpha) helix and the B-pleated sheet are best examples of secondary structure. Polysaccharides They are long chain of sugars. Monosaccharides (Simple carbohydrates having only one sugar or saccharide molecule in their constitution) are the building blocks of polysaccharides Tertiary structure: When a long peptide chain, with or without a helix, is coiled and variously folded in itself, the resulting highly specific three dimensional configuration of the protein is termed the tertiary structure. i.e.; polysaccharides are the polymerized forms of monosaccharides. There are two important classes of polysaccharides regarding their composition. They are:Homopolysaccharides: Heteropolysaccharides: Nucleic acids Nucleic acids are important macromolecules of the cell. These are complex, long-chain compounds larger than most proteins containing carbon, oxygen, hydrogen, nitrogen and phosphorus. There are two kinds of nucleic acidsDNA and RNA. Watson - Crick Model: One of the secondary structures exhibited by DNA. Quaternary structure: A protein is said to have quaternary structure if it is composed of several polypeptide chains which are not covalently linked to one another. Each polypeptide chain in such a protein, is called sub unit Plus I Biology According to this model, DNA exists as a double helix. The two strands of polynucleotides are antiparallel i.e., run in the opposite directions. The backbone is formed by the sugarphosphate-sugar chain. Winner’s Coaching Centre Biomolecules Be giving, enjoy sharing • 373 . A and G of one strand compulsorily base pairs with T and C, respectively on the other strand. There are two hydrogen bonds between A and T (A = T) There are three hydrogen bonds between G and C (G=C) energy in order to undergo a particular chemical reaction. Each strand appears like a helical staircase. Enzymes Active site: An area of enzyme surface which has a shape complementary to a particular substrate, enabling the enzyme and substrate to become temporarily bonded to form an enzyme substrate complex. Substrate: The chemical which is converted into a product is called a substrate. The catalytic cycle of enzyme action. Factors affecting enzyme activity Temperature Substrate binds to the active site of the enzyme, fitting into the active site. The binding of the substrate induces the enzyme to alter its shape. Substrate concentration The active site of the enzyme breaks the chemical bonds of the substrate and the new enzyme - product complex is formed. Temperature and PH The enzyme releases the products of the reaction. The free enzyme repeats the process. Nature of enzyme action Enzyme molecule (E) + Substrate molecule (S) → Enzyme substrate complex (ES) E+S↔ ES Complex→ EP complex → E+ P The energy level difference between substrate and product is not affected in the enzyme action. Activation energy: Extra energy that must be possessed by atoms or molecules in addition to their ground-state Plus I Biology pH. Binding of specific chemicals. Each enzyme shows its highest activity at a particular temperature and pH. The characteristic pH at which an enzyme has maximal catalytic activity is called optimum pH. Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat. Concentration of substrate With the increase in substrate concentration, the velocity of the enzymatic reaction rises at first. The reactions ultimately reaches Vmax. Vmax is the maximum velocity of an enzymatic reaction when the binding site is saturated with substrate. Winner’s Coaching Centre Biomolecules Make time for yourself • 374 . between a pair of substrates. 3. Hydrolases Enzymes catalyzing hydrolysis of ester, ether, peptide, glycosidic bonds. 4. Lyases Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds. 5. Isomerases Includes all enzymes catalyzing inter conversion of optical geometrical or positional isomers. 6. Ligases Enzymes catalyzing the linking together of 2 compounds Cofactors Non-protein constituents which are bound to the enzyme to make the enzyme catalytically active are called cofactors. In it, the protein portion of the enzymes is called the apoenzyme. Three kinds of cofactors may be identified: They are: Binding of specific chemicals: When the binding of the chemical shuts off enzyme activity, the process is called inhibition and the chemical is called an inhibitor. Prosthetic groups Coenzymes Competitive inhibitor: Metal ions. When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor. Prosthetic groups are organic compounds and are distinguished from other cofactors in that they are tightly bound to the apoenzyme. For example, in per oxidase and catalase, which catalyze the breakdown of hydrogen peroxide to water and oxygen, haem is the prosthetic group and it is a part of the active site of the enzyme. Classification and nomenclature of enzymes. Enzymes are divided into six classes. 1. Oxido reductases/ dehydrogenases Enzyme which catalyse oxidoreduction between 2 substrates S and S. 2. Transferases Enzymes catalyzing a transfer of a group Plus I Biology Coenzymes are also organic compounds but their association with the apoenzyme is only transient, usually occurring only during the course of catalysis. ie. co-enzymes serve as cofactors in a number of different enzyme cat- Winner’s Coaching Centre Biomolecules Dedication is expensive than talent • 375 . alyzed reactions. The essential chemical components of many coenzymes are vitamins, e.g. coenzyme nicotinamide adenine dinucleotide (NAD) and NADP contain the vitamin niacin. A number of enzymes require metal ions for their activity. Catalytic activity is lost when the cofactor is removed from the enzyme.eg: Zinc is a cofactor for the proteolytic enzyme carboxy peptidase. PREVIOUS YEAR QUESTIONS 1. 3.Nonprotein constituents called cofactors are bound to the enzyme to make the enzyme catalytically active. [March:2011] a.Name the protein portion of the enzyme. a. Identify this compound. b. Name the bond produced when another biomolecules of the same category combines with this. c.If a number of such molecules are bonded together, what will be the resultant molecule? [March 2013] 2. Observe the molecule given below and answer the following questions. [March 2012] a.Identify the molecule. b.What happens to the catalytic activity when the cofactor is removed from the enzyme? c.Mention any two kinds of cofactors with examples. 4. Obser the graph. a. What is meant by ’Vmax’ value? b.Why is ’Vmax’ not exceeded by any further rise in the substrate concentration? c.If a chemical substance closely resembling to that of a substrate is introduced into the reaction system, what will be the consequences? Substantiate. b.Label 1 and 2. [March:2010] c.Mention any three structural details of the molecule shown in the diagram. Plus I Biology Winner’s Coaching Centre Biomolecules You are good enough, respect yourself • 376 . 5. Fill int the blank columns with the correct terms/sentences.(3 scores) [March:2009] A IMPORTANT QUESTIONS B ……………… …. Catalyze oxido-reduction two substrates Transferase …………………………. ……………….. Catalyse hydrolysis of ester, glycosidic or C-C bonds. Lyse …………………………. ……………….. Catalyse interconversion of optical or geometric isomers. Ligase agree to it? Which is the glycosidic linkage of lactose and its monomers? ………………………….. 6. The diagram given below shows a segment of double-stranded DNA. Copy it and label the parts marked a and b. [March:2008] 7. The body of organisms are composed of four main classes of macromolecules . List out the macromolecules. [March:2007] 8. Which of the following is stronger in a DNA double helix? [March 2006] 1. By observing the relationship between the first pair, fill up the blanks. (a) Cellulose : Polysaccharide DNA : ……….. (b) Adenine : Purine Thymine : …… 2. …….. Is considered as the most abundant protein in the biosphere. 3. Amino acid proteins : Peptide bond. Monosaccharides Polysaccharides:……. 4. What role does temperature play in food preservation? 5. Identify the protein structures A and B from the following figures. 6. Which of the following amino acids is Zwitter ion, A or B or C? 9. Enzymes are biocatalysts. What do you understand from the given sequence of enzyme action? [March:2006] E+S ES E+P 10. Maltose is a disaccharide of 2 glucose molecules linked by the glycosidic linkage of C1 7. Egg albumin is a protein. When you boil egg the albumin solidifies. Why is this happening? Of the glucose and C4 of the other. Do you 8. Fill the gap. Plus I Biology Winner’s Coaching Centre Biomolecules Performance comes from practice • 377 . Inhibition of succinic dehydrogenase by malonate is an example for ………………….. c. DNA has ………. Instead of uracil 9. Observe the mode of action given below. 17. Enzymes have been classified into different groups based on the type of reaction they catalyse. Note the classes of enzymes. E + S→ ES →Ep → E → P Mention any two factors controlling it. 10. Observe the diagram of a functional enzyme given below and identify the marked regions in the figure. d. The protein part of a enzymes is….. 18. The figure shows the bonding of a biomolecule . a.Identify the monomer. b.Name the bond between the molecule. c.Name the macromolecule formed. PREVIOUS YEAR QUESTIONS ASNWERS 1. 11. “Living state is a non-equilibrium steady state”. Do you agree with this statement? Justify your answer. (a) Glycine (b) Peptide bond (c) Protein 2. (a) Watson and Crick model of DNA 12. Arrange the following carbohydrates in the order of increasing complexity of chemical structure.[ oligosac charides, Hemi cellulose, glucose, starch] 13. classify the following as polypeptide and polysaccharide. (b) 1. Thymine. 2. Hydrogen bond. (c) 1. Sugar phosphate back bone 2. Nitrogen bases face inside and are projected perpendicular to the back (Insulin, Glycogen, Chitin, Paper, RuBisCo) 14. Amino acids, rubber, drigs sugar, and spices, classify them into primary and secondary metabolites. 15. What is the significance of attaining tertiary structure by proteins? 16. Add suitable word in the gap. a. 3.A pairs with T by two hydrogen bonds and G pairs with C with three hydro gen bonds. 3. (a) Apoenzyme (b) Catalytic activity decreases A protein molecule is a polymer of ……. b. Nucleic acids are polymers of……… Plus I Biology bone. (c) 1. Prosthetic group eg: Heaem 2. Co-enzyme, eg: NAD,NADP, FAD, Winner’s Coaching Centre Biomolecules Practice makes progress • 378 . FADP. 7. 1. Carbohydrates, 4. (a) maximum velocity 2. Lipids (b) At this state, the enzyme molecules become fully saturated and no active site is left free to bind with the additional substrate molecule. All enzymes show this saturation effect. 3. Proteins (c) It will inhibit the enzyme activity. As a result, the reaction will stop. 5. 4. Nucleic acids. 8. C— G 9. In an enzyme action, the enzyme (E) reacts with substrate (S) to form an enzyme– substrate complex (ES). It then splits up into the enzyme (E) and the product (P). 10. Yes, Covalent Bond. A B Oxidoreductase Catalyse oxido-reduction between two substrates Transferase Catalyse group transfer between substrates. Hydrolase Catalyse hydrolysis of ester, glycosidic or C-C bonds. Lyse Removal of group from a substrate by clearing gouble bonds Isomerase Catalyse intersronversion of optical or geometric isomers. Ligase Catalyse linking together of two compounds IMPORTANT QUESTIONS ANSWERS 1. (a) Nucleic acid (b) Pyrimidine. 2. RuBisCo. 3. Glycosidic bonds. 4. Enzymes in the food is inactivated at very low temperatures, on gradual increase in temperature the enzyme activity is regained. 5. A - Secondary structure B– Tertiary structure. 6. B 7. The conformation of protein is changed by temperature and the protein becomes denatured. 8. Competitive inhibition. 9. 1. Temperature 6. 2. pH 10. A– Apoenzyme B– Co-factor. 11. Yes. Because, 1. Biomolecules are present in a biological system in definite concentrations. 2. Systems at equilibrium cannot perform work but living organisms work continuously. 12. 1. Glucose 2. Oligosaccharides. Plus I Biology Winner’s Coaching Centre Biomolecules Love your parents, who will never let you down • 379 . 3. Hemicellulose 4. Starch 13. Polypeptide Polysaccharide 1. RuBisCo 1. Glycogen 2. Chitin 3. Insulin 4. Paper 14. Primary metabolites Secondary metabolites 1. Amino acids 1. Rubber 2. Sugar 2. Drugs 3. Spices 15. Tertiary structure bears crevices called active sites. Active sites are essential for substrate binding during enzymatic reaction. 16. (a) Amino acids (b) Nucleotides (c) Thymine (d) Apoenzyme. 17. 1. Oxidoreductases 2. Transferases 3. Hydrolases 4. Lyases 5. Isomerases 6. Ligases. 18. (a) Glucose (b) Glycosidic bond (c) Polysaccharide Plus I Biology Winner’s Coaching Centre Biomolecules Keep calm and respect others • 380 . CHAPTER 10 CELL CYCLE AND CELL DIVISION • Chromatid One of the two identical longitudinal 1. Interphase 2. M Phase halves of a chromosome. • Centromere A button like structure occurring between the chromosomal arms of chromosomes. • Centrioles Cylindrically-shaped cytoplasmic orga nelles in animal cells which appear just outside the nucleus. It has no membrane. • spindle fibres Interphase: Fine threads of contractile protein which carry chromosomes during cell division • Kinetochores Small disc-shaped structures at the sur face of the centromeres • Bivalent Paired homologous chromosomes formed during meiosis • Tetrad The four homologous chromatids which associate during prophase and metaphase of meiosis and are involved in crossing-over. Cell cycle Plus 1 Biology • The inter phase is also called the resting phase. • It is the time during which the cell is preparing for division by undergoing both cell growth and DNA replication in an orderly manner. It is biosynthetically the most active phase. • The interphase is divided into three further phases: G1 phase (Gap 1) S Phase (synthesis) G2 Phase (Gap 2) Cell cycle: The sequence of events which a cell duplicates its genome, synthesises the other constituents of the cell and eventually divides into two daughter cells is termed cell cycles Basic phases of cell cycle • It represents the phase between two successive M phases. G1 phase • The interval between mitosis and initiation of DNA replication. • During G1 phase, the cell is metabolically active and it continuously grows but does Winner’s Coaching Centre Cell Cycle and Cell Division Learning is never done with errors and defeats • 381 . not replicate its DNA S phase • The period during which DNA synthesis or replication takes place. Mitosis is divided into the following four stages: Prophase • During this time the amount of DNA in the cell doubles. Metaphase Anaphase • However, there is no increase in the chromosome number. Telophase • In animal cells, DNA replication begins in the nucleus, and the centriole duplicates in the cytoplasm. G2 phase • Proteins are synthesised for mitosis. • Cell growth continues. Quiescent stage (G0) • The cells that do not divide further exit G1 phase to enter an inactive stage called quiescent stage (G0) of the cell cycle eg: Heart cells. • Cells at this stage remain metabolically active. but no longer proliferate unless called on to do so depending on the requirement of the organism. M phase (Mitosis phase) The phase when the actual cell division or mitosis occurs. It has two stages. They are: Karyokinesis- It is the division of the nucleus, that is, the separation of the chromosomes. Cytokinesis -It is the division of the cytoplasm M phase (Mitosis phase) Process of Mitosis Prophase: Mitosis • In mitosis, the nuclear content of a cell reproduces and divides, resulting in the formation of two new daughter cells, each containing the diploid number of chromosomes. It is the first stage pf mitosis following the S and G2 phases of interphase. • Chromosomal material condenses to form compact mitotic chromosomes. Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Don't stop learning until you are proud • 382 . • • Chromosomes are seen to be composed of two chromatids attached together at the centromere. Anaphase The centriole, which had undergone duplication (doubling) during the S phase of interphase, now begins to move towards the opposite poles of the cell. • Chromatids move to opposite poles. • The assembly of mitotic spindle begins. • Golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope disappear. • Centromeres split and chromatids (now called chromosomes separate). • The number of chromosomes at each end of the cell equals the original number. Telophase • This is the final stage of mitosis. Metaphase • Spindle fibres get attached to the kinetochores of chromosomes • Chromosomes line up randomly at the centre of the cell between the spindles, along the metaphase plate. Metaphase plate is seen at the equatorial region of the cell. • Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements. • Nuclear envelope assembles around the chromosome clusters. • Nucleolus, golgi complex and ER are formed again. Now we can say that karyokinesis has been completed. • The centromere of each chromosome replicates. Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Always desire to learn something • 383 . Syncytium - In some organisms karyokinesis is not followed by cytokinesis. As a result of this a multinucleate condition arises which is called syncytium. The key features of meiosis: eg. Liquid endosperm in coconut • Meiosis involves two sequential cycles of nuclear and cell division called meiosis I, meiosis II but only a single cycle of DNA replication. • At anaphase stage, each separated chromatid is considered as a complete chromosome. • Meiosis I begins after the replication of parental chromosomes in the 'S' phase of interphase. Significance of mitosis • Meiosis involves pairing of homologous chromosomes and recombination between them. • Restricted to diploid cells • Chromosome number remains the same in all vegetative cells. • The genetic constitution of the daughter cells is the same as that of the parent cell. • Mitosis helps the body growth of multicellular organisms and to repair the damage. • It is useful for replacement of lost cells. • It helps unicellular organisms to increase in number. • Four haploid cells are formed at the end of meiosis II Meiosis • It is a specialised kind of cell division that reduces the chromosome number in a diploid cell by half, resulting in the production of haploid daughter cells. Meiosis occurs during gametogenesis in plants and animals. • Meiosis involves two division sequences separated by a resting phase and results in the formation of four new cells, each having the haploid number of chromosomes. • Meiosis is called reduction division. Why? Meiosis occur in sex organs and the diploid number of chromosome is reduced to half to form gametes. Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Learn to appreciate others • 384 . Meiosis/ Process of meiosis occurs First meiotic division This stage begins with one parent cell and ends with two daughter cells, each containing the haploid number of chromosomes. • Unpairing of homologous chromosomes starts and Chiasmata are first seen. • Chiasmata are the points of contact where interchange of chromosome material takes place between chromatids of two homologous chromosomes. Diakinesis • It is the final stage of meiotic prophase I • Terminalisation of chiasmata occurs. Chromosomes are fully condensed. • Meiotic spindle is assembled. • Nucleolus disappears and the nuclear envelope breaks down. Phases Prophase I Leptotene The chromosomes are long, thin and threadlike at this stage and gradually visible under light microscope. Zygotene • Synapsis occurs. It is the pairing of homologous chromosomes. 4 distinct chromatids are seen and is called tetrad stage. • Synaptonemal complex is formed - (It is a structural component situated between a pair of synapsed homologous chromosomes). Pachytene Recombination nodules appear. These are the sites at which crossing over (exchange of genetic material between two homologous chromosomes) occurs between non-sister chromatids of the homologous chromosomes. This results in recombination of genes. Diplotene • Dissolution of the synaptonemal complex Plus 1 Biology Metaphase I. • Pairs of bivalent chromosomes line up randomly along the metaphase plate. • Spindle fibres attach to each chromosome pair; centromeres do not replicate. Winner’s Coaching Centre Cell Cycle and Cell Division Sometimes you win, sometimes you learn • 385 . Anaphase I • The bivalent pairs separate, with spindle fibres pulling the homologous, double stranded chromosomes to the opposite ends of the cell. Reduction in chromosome number occur at this phase. • Because the centromeres have not divided, the chromatids remain attached. Telophase I • The nuclear membrane and nucleolus reappear. • Telophase I is followed by cytokinesis in which the cytoplasm compresses and divides the cell into two halves. • Each new cell contains the haploid number of chromosomes. Interkinesis • This is a short interval between the two meiotic divisions • The nucleus and nuclear mem brane are well defined. • Each chromosome consists of two chromatids that do not replicate. Second Division This stage is essentially a mitotic division. It begins with two new daughter cells, each containing the haploid number of chromosomes, and ends with four new haploid cells. Prophase II • The nuclear membrane disappears • The chromosomes again become compact; they do not synapse Metaphase II • Chromosomes align at equator. Spindle fires attach to the centromere. Anaphase II • The chromatids separate; each is now a singlestranded chromosome. • Chromosomes move away from one another and are pulled to the opposite ends of the cell. Telophase II • Meiosis ends with telophase II • The two groups of chromosomes once again get enclosed by a nuclear envelope. Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Learning is a treasure that follows you everywhere • 386 . • After telophase II, cytokinesis follows. In this process, the cytoplasm of each cell compresses and divides the cells into two halves leaving a total of four new daughter cells each containing the haploid number of chromosomes. A B Zygotene (a) (b) Crossing over (c) Dissolution of synaptonemal complex Diakinesis (d) Significance of meiosis • Four haploid daughter cells are formed from a single diploid cell. • The chromosome number is restricted to half in the gametes. • Avoids unnecessary duplication of chromosomes in fertilization. • Genetic variation occurs in offspring due to the exchange of genetic material during crossing over. • (March 2020) 3. The stage at which synapsis occurs during prophase 1. (2020) 4. Meiosis maintains the chromosome number of a species constant. • Helps to maintain vigour in the progeny through sexual reproduction 5. Previous Year HSE Questions 1. - - - - - - - : Chromatids move to opposite poles. ( March 2020) 2. Analyse the table given below and fill in the blanks. a) Write three phases of interphase. b) Write the peculiarity of quiescent stage (G0). (2020) Fill in the blank: 6. Karyokinesis of mitosis is divided into four stages. Name the second and third stage. Write any two features of second stage. (March 2019) 7. Crossing over occurs in -------- substage of prophase 1 8. Plus 1 Biology During interphase stage cells prepare for cell division. Cytokinesis in animal cell takes place by the appearance of a ------- in the plasma membrane. (March 2019) Observe the relationship between the first two terms and fill in the blank. Metaphase: Spindle fibres attach to kinetochores. Name of the following: a) Leptotene b) Zygotene c) Diplotene d) Pachytene (2019) Given below is the diagrammatic representation of a particular stage mitosis: Winner’s Coaching Centre Cell Cycle and Cell Division Exercise changes your attitude • 387 . (2018) 12. 9. a) Identify the stage. b) Write any two features of these stage. (2019) First phase of meiosis I is typically longer and complex one. Name it. Mention the five subdivisions of this phase. Observe the given stage of mitosis. Identify the stage and write any two features of it. (2018) 13. (March 2018) 10. Certain stages in cell cycle are given below: Given below is the metaphase of mitosis. Analyse the diagram and draw a sketch of anaphase. Write any two events of anaphase. Karyokinesis, prophase, cytokinesis, metaphase, anaphase, telophase Choose the statements (from those given below) that match with these stages and prepare a table. • Centromere split and chromosomes move to opposite poles. • Chromosomes cluster at opposite poles and nuclear envelope assembles around. • Chromosomes seems to be with two chromatids attached at centromere • Chromosomes arranged at spindle equator. • Separation of daughter chromosomes. • 11. (March 2017) 14. Give the scientific term of the following: Interchange of genetic material between con-sister chromatids of homologous chromosomes. (2017) 15. “Meiosis is highly significant in sexually reproducing organism.” Justify. (2017) 16. (a) identify the substage of meiosis in which crossing over is occurring. (i) Leptotene (ii) Zygotene (iii) Pachytene (vi) Diplotene (b) Division of Cytoplasm. Fill in the blanks. Small disc– shaped structures at the surface of the centromere are called ------ Plus 1 Biology 17. Summarize the significance of meiosis in sexually reproducing organisms. (March 2016) Identify the substages of prophase I of meiosis in which the following events Winner’s Coaching Centre Cell Cycle and Cell Division To lose patience is to lose battle • 388 . take place. Mention two significance of meiosis. 18. a) Dissolution of the synaptonemal complex b) Crossing over c) Pairing of homologous chromosome d) Terminalisation of chiasma of chiasma (2016) Observe the diagrams, Identify the A and B stages of mitosis. Write any two identifying features of each stage (2016) 19. 20. Due to the presence of a secondary constriction, a knob– like small fragment appears in some chromosomes called…… (March 2015) Important Questions 1. Which stage of Meiosis crossing over of genetic material takes place? 2. Name the cells in which Meiosis occurs. 3. Mitosis is characterized by ………. 4. Which phase is the longest in the cell cycle? 5. Cell division that is known as reduction division is………. 6. Observe the relationship between the first two terms and fill in the blank: Prophase: Nucleolus and golgi complex disappear ………. : Nucleolus and golgi complex reform 7. Observe the diagrammatic view of a cell cycle and answer the questions. a) Identify the phase, in which DNA synthesis takes place. b) Mention any one event that takes place in the stages marked as X and Y. (March 2015) 8. 9. Plus 1 Biology Condensation of chromosomes occur in ………. a) Prophase I b) Prophase II c) Anaphase d) Metaphase Which stage is the connecting link between Meiosis I and Meiosis II? a) Interphase I b) Interphase II c) Interkinesis d) Anaphase I Mitosis occurs in Winner’s Coaching Centre Cell Cycle and Cell Division Patience is waiting with good attitude • 389 . 10. 11. 12. 13. a) Haploid individuals b) Diploid individuals c) Both (a) and (b) d) In bacteria only If there were 4 chromosomes present during prophase, how many chromosomes are there in each cell at the end of anaphase II? 14. Anaphase and Anaphase I leads to separation of chromosomes in different ways. Substantiate the statement with suitable explanation. 15. Notice the four stages of mitosis give below 1) Prophase a) 16 b) 4 2) Metaphase c) 2 d) 8 3) Anaphase 4) Telophase (a) Identify the stage at which the maximum condensation of chromosomes occur. (b) Name the stage that follows the above identified stage and write any two peculiarities of the stage. Terminalisation of chiasmata occurs in which stage? a) Pachytene b) Diplotene c) Zygotene d) diakinesis 16. Choose the correct answer: Karyokinesis is followed by cytokinesis. Synapsis is associated with a) Define cytokinesis. a) Pachytene b) b) Zygotene Differentiate cytokinesis in plant cell and animal cell. c) Leptotene d) Diplotene 17. Complete the illustration related to cell cycle appropriately. During diakinesis terminalization of chiasmata occurs. a) Write any other two changes that occur during this stage. b) Identify the stage that follows diakinesis. 18. Continuation of life mainly depends on meiotic division. Substantiate. 19. Using the hints I and II given below , make suitable pairs as in the example provided . [ Hint I : Synapsis, compaction of chromosomes, dissolution of synaptonemal complex, crossing over, terminalization of chiasmata] [Hint: II zygotene, diakinesis, diplotene, Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Trying now is better than trying later • 390 . pachytene, leptotene] 20. Chromatids move to opposite poles. List the main differences between Mitosis and Meiosis. 9. Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis Previous year questions 1. Prophase I Anaphase 2. 10. Zygotene Synaptonemal complex (a) Pachytene (b) Diplotene (c) Anaphase/ Karyo- Centromere splits kinesis and chromosomes move to opposite Crossing over Telophase/ Karyo- Chromosomes kinesis cluster at opposite poles and nuclear envelope assem- Dissolution of synaptonemal complex Diakine- Terminalisation of chisis asmata (d) 3. Zygotene 4. (a) G1 phase, S phase and G2 phase (b) Metabolically active but no longer proliferate. 5. Cleavage furrow 6. Metaphase, Anaphase Features of metaphase 1. Metaphase plate 2. All chromosomes at equator 3. Chromosome at maximum condensation 4. Spindle fibres attached to kinetochores 7. d) Pachytene 8. (a) Anaphase Prophase/ Metaphase/ Karyokinesis Chromosomes seem to be with two chromatids attached at centro- Metaphase/ Karyokinesis Chromosomes arranged at spindle Anaphase/ Karyokinesis Separation of daughter chromo- Cytokinesis Division of cytoplasm 11. Kinetochore 12. Telophase 1. Chromosomes cluster at opposite poles. 2. Nuclear envelope assemble around chromosome cluster. (b) Centromers splits and chromatids separate. Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Investment in knowledge pays the best interest • 391 . separate. 13. (2) Movement of daughter chromosomes towards the opposite poles of the cell. 19. Statellite chromosomes 20. (a) S phase (b) x-Metaphase 1. Centromeres split and chromatids separate. 2. Chromatids move to opposite poles. 14. Crossing over. 15. It ensures the conservation of specific chromosome number. It causes the variation of genetic character. 16. a) Pachytene b) Conservation of specific chromosome number of each species is achieved across successive generations in sexually reproducing organisms through meiosis. 17. (a) Diplotene (c) Zygotene (b) (d) Pachytene Diakinesis Significance of meiosis 1) 2) 18. Chromosome number constantly maintained Variation occurs and formation of new species (a) Metaphase Chromosomes arranged at the equator. Y– Anaphase Centromere divides and chromatids move towards the opposite poles. Important question answers Fill in the blanks 1. Pachytene 2. Reproductive cells or germ cells 3. Equational division 4. Interphase 5. Meiosis 6. Telophase 7. Prophase I 8. Interkinesis 9. Both (a) and (b) 10. 2 11. Diakinesis 12. Zygotene 13. Features (1) Formation of spindle apparatus (2) Chromosomes are arranged at the equator (b) Anaphase Features (1) Plus 1 Biology Centromers splits and chromatids Winner’s Coaching Centre Cell Cycle and Cell Division Today a reader, Tomorrow a leader • 392 . 14. Anaphase Anaphase 1 Centromere splits and chromatids move to opposite poles Homologous chromosomes separate and move to opposite poles while sister chromatids remain associated at their centromeres 15. 20. Mitosis In mitotic di- 1. Meiotic division vision, a sininvolves two gle division , successive diviresults in two sions– Meiosis I daughter and Meiosis II. cells. These divisions result in four daughter cells 2. Mitosis is 2. Meiosis I is known as known as reducequational tional division. division. This This is because is because the the chromosome daughter cells number is rehave the same duced to half. diploid numMeiosis II is ber of chroknown as equamosomes as tional division. the parent. This is because the sister chromatids separate and the chromosome number remains the same. 3. Prophase is 3.Prophase I is very short and does long and comnot comprise prises 5 phases: any phase. Leptotene, zygotene, pachytene, diplotene and diakinesis. (a) Division of cytoplasm (b) Animal cell: Furrow appear in the plasma membrane which gradually deepens and joins in the centre. Plant cell: Cell plate formation starts in the centre of the cell and grows outward to meet the existing lateral walls. 17. (a) Chromosomes get fully condensed. Nucleus disappears and nuclear envelope breaks down. (b) Metaphase I 18. (1) Meiosis is reduction division that ensures formation of haploid gamete in sexually reproducing organisms. (2) 19. It causes genetic variability tat leads to evolution. Leptotene - Compaction of somes chromo- Meiosis 1. (a) Metaphase (b) Anaphases: Centromere splits and chromatids separate. Chromatids move to opposite poles. 16. Diakinesis - Terminalisation of chiasmata Zygotene - Synapsis Pachytene - Crossing over Diplotene - Dissolution of synaptonemal complex Plus 1 Biology Winner’s Coaching Centre Cell Cycle and Cell Division Think like a proton, always positive • 393 . 4. There is no 4. In the zygotene pairing of stage of prochromophase, the pairsomes, ing of chromocrossing somes occurs. over or chi- During pachyasmata for- tene, crossing mation dur- over occurs. ing pro- Chiasmata are phase. formed in the 5. Synap5. Synaptonemal tonemal complex oi complex is formed durnot formed. ing the zygotene stage of 6. Anaphase 6. involves the separation of the chromatids of each chromosome. Plus 1 Biology 7. Mitosis plays 7. Meiosis brings a significant about variation role in the and maintains healing repair, the chromoand growth of some number a cell. from generation to generation. During anaphase I, the homologous chromosomes separate while the chromatids remain attached at their centromeres. During anaphase II, the chromatids separate as a result of the splitting of the centromere. Winner’s Coaching Centre Cell Cycle and Cell Division