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ALGAEAlgae are mostly aquatic, some being terrestrialalso.A few algae grow on other plants.Aquatic algae grow in marine water or fresh waterThey may be small, unicellular, microscopic likeChlorella (non-motile), Chlamydomonas (motile)or multicellular unbranched filamentous likeSpirogyra and Ulothrix,or branched filamentous like Charaor colonial forms like Volvoxor huge macro-scopic such as sea weeds which measure more than 60 meters inlength. e.g. Sargassum dr.aarif
The algal cell wall consists of two layers i.e. inner cellulosic and outer composed ofpectin.The algae consist of various types of photosynthetic pigments.Chlorophyll-a is an(essential pigment)CarotenoidsPhycobilins.The reserve food material is in the form of starch, laminarin ,starch, mannitol orfloridean-starch, etc. dr.aarif
REPRODUCTION IN ALGAE Reproduction Sexual Vegetative AsexualFragmentation (in By the formation of formation and fusionfilamentous forms) various types of non- of gametes. motile or motile spores.and Isogamy : fusing gametes are The most common being samecell division (in the zoospores. Anisogamy : fusing gametesunicellular forms). are different They are flagellated Oogamy : fusing gametes (motile) and on are totally different, germination gives rise to enough to be called as new plants. male and female gametes dr.aarif
At least a half of the total carbon dioxide fixation on earth is carried out by algae throughphotosynthesisBeing photosynthetic they increase the level of dissolved oxygen in their immediateenvironment.They are of paramount importance as primary producers of energy-rich compounds whichform the basis of the food cycles of all aquatic animals.Many species of Porphyra, Laminaria and Sargassumare among the 70 species of marinealgae used as food.Certain marine brown and red algae produce large amounts of hydrocolloids (waterholding substances), e.g., algin(brown algae) and carrageen (red algae) are usedcommerciallyAgar, one of the commercial products obtained from Gelidium and Gracilaria are used togrow microbes and in preparations of ice-creams and jellies.Chlorella and Spirullina are unicellular algae, rich in proteins and are used as foodsupplements. dr.aarif
ALGAEChlorophyceae Phaeophyceae Rhodophyceae (green algae) (brown algae) (red algae) They are usually grass green due to the dominance of pigments chlorophyll a and b.The pigments are localised in definite chloroplasts.The chloroplasts are of different shapes; discoid, plate-like, reticulate, cup-shaped,spiral or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in thechloroplasts. Pyrenoids contain protein besides starch. Some algae may store food inthe form of oil droplets. Green algae usually have a rigid cell wall made of an inner layer of cellulose and anouter layer of pectose.Vegetative reproduction usually takes place by fragmentation or by formation ofdifferent types of spores.Asexual reproduction is by flagellated zoospores produced in zoosporangia.The sexual reproduction shows considerable variation in the type and formation of sexcells and it may be isogamous, anisogamous or oogamous.The common forms are Ectocarpus, Dictyota, Laminaria, Sargassumand Fucus. dr.aarif
ALGAEChlorophyceae Phaeophyceae Rhodophyceae (green algae) (brown algae) (red algae) The members of phaeophyceae or brown algaeare found primarily in marine habitats.They show great variation in size and form.They range from simple branched, filamentous forms [Ectocarpus] to profuselybranched forms as represented by kelps, which may reach a height of 100 metres. Theypossess chlorophyll a,c, carotenes and xanthophylls,They vary in colour from olive green to various shades of brown depending upon theamount of the xanthophyll pigment, fucoxanthin present in them.Food is stored as complex carbohydrates, which may be in the of laminarin ormannitol. The vegetative cells have a cellulosic wall dually covered on the outside by agelatinous coating of alginVegetative reproduction takes place by fragmentation.Asexual reproduction in most brown algae is by biflagellate zoospores that are pear-shaped and have two unequal laterally attached flagella.Sexual reproduction may be isogamous, anisogamous or oogamous.The common forms are Ectocarpus, Dictyota, Laminaria, Sargassumand Fucus. dr.aarif
ALGAEChlorophyceae Phaeophyceae Rhodophyceae (green algae) (brown algae) (red algae)The members of rhodophyceae are commonly called red algaebecause of thepredominance of the red pigment, r-phycoerythrin in their body.Majority of the red algae are marine with greater concentrations found in the warmerareas.The red thalli of most of the red algae are multicellular. The food is stored as floridean starch which is very similar to amylopectin andglycogen in structure.The red algae usually reproduce vegetatively by fragmentation.They reproduce asexually by non-motile spores andsexually by non-motile gametes.Sexual reproduction is oogamous and accompanied by complex post fertilisationdevelopments.The common members are: Polysiphonia, Porphyra, Gracikma and Gelidium. dr.aarif
BRYOPHYTAMostly terrestrial plantswhich depend onexternal water for fertilization and completionof their life cycle.Hence they are called `amphibian plantsGrow in shady and moist places such as moistwalls, damp rocks, moist soil and on decayinglogs.They show thalloid plant body which is notdifferentiated into root, stem and leaves.In Bryophytes true roots are absent butrhizoids are present.Rhizoids are unicellular in liverworts, whilemulticellular in mosses. They absorb water and minerals and also helpin fixation of thallus to the substratum. dr.aarif
GAMETOPHYTE SPOROPHYTEThe main plant body(thallus) of the The zygote produces a multicellular bodybryophyte is haploid. called a sporophyte.It produces gametes, hence is called agametophyte The sporophyte is not free-living but The sex organs in bryophytes are attached to the photosyntheticmulticellular. gametophyte and derives nourishmentThe male sex organ is called from it.antheridium. They produce biflagellateantherozoids. Some cells of the sporophyte undergo The female sex organ called reduction division (meiosis) to producearchegonium is flask-shaped and haploid spores.produces a single egg. The antherozoids are released into These spores germinate to producewater where they come in contact with gametophyte.archegonium. An antherozoid fuses withthe egg to produce the zygote. Thus, the sporophyte is diploid,The gametophyte is the dominant, recessive and partially dependent ongreen, haploid and independent gametophytephase. dr.aarif
Economic Importance of Bryophytes1. Some mosses provide food for herbaceous mammals, birds and other animals. 2. Species of Sphagnum, a moss, provide peat that have long been used asfuel, and because of their capacity to hold water as packing material for trans-shipment of living material.3. Mosses, along with lichens are the first organisms to colonise rocks andhence, are of great ecological importance. They decompose rocks making thesubstrate suitable for the growth of higher plants.4. Since mosses form dense mats on the soil, they reduce the impact of fallingrain and prevent soil erosion dr.aarif
Bryophyta Hepaticopsida Anthoceratopsida Bryopsida (Liverworts) (Hornworts) (Mosses). The plant body of a liverwort is thalloid, e.g., Marchantia .Thethallus is dorsiventral and closely appressed to the substrate. Theleafy members have tiny leaf-like appendages in two rows on thestem-like structures.Asexual reproduction in liverworts takes place by fragmentation ofthalli, or by the formation of specialised structures called gemmae(sing, gemma). Gemmae are green, multicellular, asexual buds,which develop in small receptacles called gemma cups located onthe thalli (see diagram). The gemmae become detached from theparent body and germinate to form new individuals.During sexual reproduction, male and female sex organs areproduced either on the same or on different thalli. The sporophyte isdifferentiated into a foot, seta and capsule. After meiosis, sporesare produced within the capsule. These spores germinate to formfree-living gametophytes.
Bryophyta Bryopsida Hepaticopsida Anthoceratopsida (Mosses) (Liverworts) (Hornworts)The gametophyte which consists of two stages. The first stage is the protonema stage, which develops directly from aspore.The second stage is the leafy stage, which develops from the secondaryprotonema as a lateral bud. They consist of upright, slender axesbearing spirally arranged leaves. They are attached to the soil throughmulticellular and branched rhizoids. This stage bears the sex organs.Vegetative reproduction in mosses is by fragmentation and budding in the secondary protonema.In sexual reproduction, the sex organs antheridia and archegonia areproduced at the apex of the leafy shoots. After fertilisation, the zygotedevelops into a sporophyte, consisting of a foot, seta and capsule.The sporophyte in mosses is more elaborate than that in liverworts. Thecapsule contains spores. Spores are formed after meiosis. The mosseshave an elaborate mechanism of spore dispersal. Common examples ofmosses are Funaria, Polytrichum and Sphagnum.
PTERIDOPHYTAThe first vascular plants and the first successfulterrestrial plants with true roots, stem and leaves but no flowers fruits and seedsCalled as VASCULAR CRYPTOGAMSThe Pteridophytes include horsetails and ferns.The Pteridophytes are terrestrial, small, eitherannual or perennial, and grow luxuriantly incool, moist and shady places. e.g. ferns.They may be aquatic(Azolla, Marsilea), xerophytic(Equisetum) epiphytic(Lycopodium) i.e.growing on large trunks of trees dr.aarif
PTERIDOPHYTA Plant BodyThe primary root is short-lived and is soon replacedby adventitious rootsStem may be aerial or underground.The leaves may be scaly (Equisetum), simple and sessile (Lycopodium) or large and pinnately compound (Ferns).The leaves in pteridophyta are small(microphylls) asin Selaginella or large(macrophylls) as in Ferns.In pteridophytes, the xylem consists of only tracheidsand phloem consists of sieve cells only. Secondary growth is not seen in Pteridophytesdueto absence of cambium. dr.aarif
PTERIDOPHYTA HETEROMORPHIC ALTERNATION OF GENERATION dr.aarif
PTERIDOPHYTA REPRODUCTIONThe sporophyte shows asexual reproduction and produces spores by meiosis from which thegametophyte develops.The gametophyte is haploid,recessive but independent, and reproduces sexually.Product of sexual reproduction, i.e. zygote produces diploid sporophyte.Spores are produced in special multicellular structures called sporangia.The sporangia areproduced by leaf-like appendages called sporophylls. In some cases,sporophylls may form distinct compact structures called strobili orcones(Selaginella, Equisetum).The sporangia produce spores by meiosis in spore mother cells.The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostlyphotosynthetic thalloid gametophytes called prothallus. dr.aarif
These gametophytes require cool, damp, shady places to grow.The gametophytes bear male and female sex organs calledantheridia and archegonia, respectively.Water is required for transfer of antherozoids - the male gametes released from theantheridia, to the mouth of archegonium.Fusion of male gamete with the egg present in the archegonium result in theformation of zygote.Zygote thereafter produces a multicellular well-differentiated sporophyte which isthe dominant phase of the pteridophytes. In majority of the pteridophytes, all thespores are of similar kinds; such plants are called homosporous. Genera likeSelaginella and Salvinia which produce two kinds of spores, macro (large) and micro(small) spores, are known as heterosporous. The megaspores and microsporesgerminate and give rise to female and male gametophytes, respectively. The femalegametophytes in these plants are retained on the parent sporophytes for variableperiods. The development of the zygotes into young embryos take place within thefemale gametophytes. dr.aarif
The Pteridophytes, apart from normal way of reproduction, also sometimes show followingmethods:1.Apogamy- It is the development of the sporophyte without the fusion of the male andfemale gametes. It arises directly from the gametophyte. Here the sporophyte is haploid.2. Apospory- It is the development of the gametophyte from any cell of the sporophyteother than the haploid spores. Such a gametophyte is diploid in nature. Pteridophyta Psilopsida Lycopsida Sphenopsida Pteropsida Psilotum Selaginella Equisetum Pteris Lycopodium Dryopteris Adiantum dr.aarif
ANGIOSPERMSMost advanced division of the flowering plantsHighly evolved plants, primarily adapted toterrestrial habitat.Wolffia is the smallest angiosperm, l mm in size andEucalyptusgrows to over 100 meters.The plant body is differentiated intoroot, stem and leaves.It has flowers, fruits and seeds.Vascular tissues are well developed. Xylem shows vessels or tracheae while phloem has sieve tubes and companion cells. dr.aarif
DICOTYLEDONAE MONOCOTYLEDONAE 2 cotyledons in the Embryo 1 cotyledon in the Embryo Tap root system Adventitious root system Stem is profusely branched Stem is unbranched Reticulate Venation Parallel Venation Flowers show tetramerous or Flowers show trimerous symmetry pentamerous symmetryVascular Bundle is Conjoint, Collateral and Vascular Bundle is Conjoint, Collateral and open closed Secondary growth is found Secondary growth is absent dr.aarif
GYMNOSPERMSMost of the Gymnosperms are evergreen,perennial woody trees or shrubs. The gymnosperms are plants in which theovules are not enclosed by any ovary wall andremain exposed, both before and afterfertilisation.They are non-flowering plants producingnaked seeds (fruits are not produced).Xylem has tracheids andphloem with sieve cells. dr.aarif
GYMNOSPERMSThe plant body i.e. sporophyte is differentiated intoroot, stem and leavesROOTS :Specialized Coralloid roots of Cycas show association with N2-fixing blue-green algae andPinus show association with endophytic fungi calledmycorrhizaeSTEM :The gymnospermic stem is mostly erect, aerial, solid andcylindrical.In Cycas, it is unbranched, while in Pinus, Cedrus and conifers it is branchedLEAVES :The leaves are dimorphic.The foliage leaves are simple, needle like or pinnatelycompound Scale leaves are small, membranous and brown. dr.aarif
The gymnosperms are heterosporous; theyproduce haploid microspores and megaspores.The two kinds of spores are produced withinsporangia that are borne on leafy structurescalled sporophylls which are arranged spirallyalong an axis to form lax or compact strobili orcones.The strobili bearing microsporophylls andmicrosporangia are called male strobili or maleconeThe microspores develop into a malegametophytic generation which is reduced andis confined to only a limited number of cells.This reduced gametophyte is called a pollengrain. The development of pollen grains takeplace within the microsporangia. dr.aarif
The cones bearing megasporophyllswith ovules are called female strobili orfemale coneThe male or female strobili may beborne on the same tree (Pinus). However in Cycas, male cones andmegasporophylls are borne on differenttrees. The megaspore mother cell isdifferentiated from one of the cells ofthe nucellus (nutritive tissue of theovule).
GYMNOSPERMS HETEROMORPHIC ALTERNATION OF GENERATIONSPOROPHYTEDiploidDominantIndependentGAMETOPHYTEHaploidRecessiveDependent dr.aarif
The nucellus (megasporangia) is protected by envelopes and the compositestructure is called an ovule. The megaspore mother cell divides meiotically to formfour megaspores. One of the megaspores develops into a multicellular femalegametophyte that bears two or more archegonia or female sex organs. Themulticellular female gametophyte is also retained within megasporangium dr.aarif
The pollen grain is released from the microsporangium. The pollination in Gymnosperm isanemophilous (wind pollination). The pollen grains come in contact with the opening of theovules borne on megasporophylls.The pollen tube carrying the male gametes grows towards archegonia in the ovules anddischarge their contents near the mouth of the archegonia. Following fertilization, zygotedevelops into an embryo and the ovules into seeds. These seeds are not covered.The fertilization is direct as the pollen grains are received directly in the pollen chamber ofthe ovule. Fertilization is achieved through a pollen tube. This process is calledsiphonogamy. dr.aarif
Gymnospermae Cycadopsida Coniferopsida Gnetopsida e.g.Cycas e.g. Pinus e.g. Gnetum Zamia Sequoia Ephedra Angiosperms Gymnosperms1. Ovules are enclosed in the ovary 1. Ovules are naked2. Pollen chamber and pollination drop are 2. Pollen chamber and pollination drop areabsent present3. Archegonia are absent 3. 2-8 archegonia are present4. Each ovule has only 1 female gamete 4. 1 ovule has 2-8 female gametes5. Double fertilization 5. No double fertilization6. Endosperm is triplod and formed after 6. Endosperm is haploid and formed beforefertilization fertilization dr.aarif
LIFE CYCLES Haplontic Haplo-diplontic DiplonticThe dominant, Bryophytes and diploid sporophyte isphotosynthetic phase in pteridophytes, the dominant,such plants is the free- interestingly, exhibit an photosynthetic,living haploid intermediate condition independent phase of thegametophyte. (Haplo-diplontic); both plant. This kind of life cycle phases are This kind of life cycle isis termed as Haplontic. multicellular. called as Diplontic•Many algae such as However, they differ in Gymnosperms andVolvox, Spirogyra their dominant phases Angiosperms dr.aarif