SURFACE CHEMISTRY_ADVANCED # 1

Topic

Contents

KINGDOM PLANTAE

SyllabusKINGDOM PLANTAE

Algae,Chlorophyta,Brophyta,Pteridophyta, Some important points

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Algae

ChlorophytaBrophyta

Pteridophyta

Some important points

KINGDOM- PLANTAE

All the multicellular eukaryotic plants are placed in kingdom- plantae. They are autotrophic i. e. they manufacture their food photosynthesis.

Following plant groups are included in kingdom- plantae

(3) PTERIDOPHYTA(1)ALGAE (2) BRYOPHYTA(4) GYMNOSPERM (5) ANGIOSPERM

ALGAETerm'' Algae '' was given by Linnaeus.Phycology- Study of algae.Father of Phycology → Fristch → Book → Structure & Reproduction of algae''Father of Indian phycology- M.O.P.IyengarNATURE

(1) Algae are found in both fresh and marina water.(2) Algae are found in many forms like filamentous, colonial.(3) Algae are surrounded by mucilaginous sheath and below the sheath cell wall is present which is made up

(4)

(5)

(6)

of cellulose and pectin but mainly made up of cellulose, galactans, mannans and mineral like calciumcarbonateOn the basis of structure, algae are thalloid i. e. plant body is not differentiated into root, stem and leavesTissue system is also absent in algae.On the basis of nutrition, algae are photoautotrophic. They have chioroplast in which photosynthrricpigments are present. Classification of algae is mainly based pigments. Chl-a and B carotene are univer-sal pigments of algae.Cell wall of algae is made uo of cellulose a pectin, gallactose a mannose(1) Vegetative (2) Asexual (3) Sexual

Vegetative reproduction(i) Binary fission - cell divided into two parts and nucleus is also divided into two parts by mitosis.

eg. Found only in unicellular algae

(ii) Fragmentation - Filaments break down into smll pieces from new filaments.eg. All filamentous algae

Asexual reproduction :(i)(ii)

By different types of spores like zoospore, aplanospore, hypnospore akinetes.Zoospores are formed in favourable conditions and Aplanospores, hypnospore and akinete etc. areformed unfavourable condition.

(iii) Thick walled spores (Hypnospres akinetes) also protect the algae from unfavourabke condition so theyare the methods of pernnation also.

Sexual reproduction :(i) Male sex organ is called antheridium and female called oogonium. The sex organs of algae are unicellular

& jacketless. But exceptionally sex organs of green algae Chara (chara-green-algae known as stonewort) are multicellular and jacketed.The male sex organ of Chara is known as globule and female is known as nucule.

(ii) Plant body of algae is haploid so sexual repro. Take place through zygotic meiosis. So their life cycle ishaplontic. But exceptionally brown algae are diploid and sexual reproduction tack place throughgemtic meiosis in them.The life cycle of brown algae is diplona-plontic.

(iii) Algae reproduce by zygotic meiosis i.e. first division in zygote is meiosis so embryo is not formed.

Sexual repro. Is of three types

(a) Isogamous - Chlamydomonas debaryanum, Ulothrix, Ectocarpu, Spirogyra

(b) Anisogamous - Chlamydomonas braunii

(c) Oogamous - Chlamydomonas coccifera, Sargassum, Volvos Fucus

Note: (1) chlamydomanas exhibits complet evolution of sexual reproduction.(2) In chlamydomanas debaryanum gametes are flagellated and similar in size.(3) In chlamydomonas braunii gametes are motile and dissimilar in size.

The classification of algae is mainly based on the photosynthetic pigments. In addition to this, cellwall composition and stored food are also the base of classification.

Algae is divided into following divisions

(1) CHLOROPHYTA - GREEN ALGAE

(2) PHAEOPHYTA - BROWN ALGAE

(3) RHODOPHYTA - RED ALGAE

PLANT KINGDOM (PLANTAE)

Some important Points about Algae

Atleast a half of the total CO2 fixation (photosynthesis) on earth is carried out by algae, because on earthwater is present in 2/3rd part.

They perform oxygenic photosynthesis, so they increase the level of dissolved oxygen in their immediate(nearby) environment.

They are primary producers (autotrophs) of energy rich compounds which form the basis of food cycles ofall aquatic animals.

As the producers algae are of paramount importance. About to species of marine algae are used as food. Hydrocolloids or phycocolloids :- The colloidal substances obtained from algae which have very high

water holding capacity are known as phycocolloids eg. Algin, Carrageen & Agar Agar. Pyrenoids :- They are storage bodies located in the chloroplast in these bodies protein are present around

which starch is also there. Means pyrenoids are made of proteins & starch.

Classes Common Major Pigment Stored Cell wall Flagellar HabitatName food wall number &

position ofinsection

Chlorophyceae Green Chlorophyll Starch Cellulose 2-8, equal, Fresh wateralgae a, b apical brackish

water, salt water

Phaeophyceae Brown Chlorophyll Mannitol, Cellulose 2, unequal, Fresh wateralgae a, c, Laminarin & algin lateral (rare) bracicish

fucoxanthin water, salt water

Rhodophyceae Red Chlorophyll Floridean Cellulose Absent Fresh wateralgae a, d,

Phycoerythrinstarch (some),

brackish water,salt water(most)

CHLOROPHYTA All the algae, included in this division are green in color. Green algae are the most advanced algae. Itisbelieved that green algae the anccestors of the higher plants. Green algae usually have a rigid cell wall made up of an inner layer of cellulose an outer layer of pectose. Habitat : Green algae are cosmopolitan in nature.Different forms of Green algae (Structure):

Green algae are found in many forms(1) Unicellular :-

(i) Chlamydomonas - Motile unicellular algae. This moves with the help of flagella.(ii) Chlorella - Non motile unicellular alga.

Calvin discovered'' calvin cycle'' by experimenting on chlorella.(iii) Acetabularia - Umbrella plant- It is the largest unicellular plant . The diameter of its cell is 10 cm.

Hammerling experimented on Acetabularia.Note: According tofive kingdom system the algae described above should be placed in Protista but due totheir life cycle is similar to green algae so they studied in plantae.

(2) Colonial - Some green algae are found in colonies. They from colony of cell. The number of cell in acolony is fixed. Colony with fixed number of cells coenobium.

eg. Volvox - Motile colony(3) Multicellular filamentous - Mostlyn the green algae are multicellular and filaentous.

eg. Ulothrix - known as pond woolSpirogyra - known as pond silk

(4) Multicellular thlloid or parenchymatous - some algae are multicellular in length & width.eg. Ulva - Also called as sea lettuce

Photosynthetic pigments:Chlorophyll - Chl' a' and Chl' b'Carotene - caroteneXanthophyll - Luteaxanthin and Violoxanthin- Yellow coloured

Note: 1. On the basis of pigment (Chl ' a', Chl 'b', carotenoids), stored food (starch) & cell wall(made up of cellulose or prctose), green are considered similar to higher plants.]

2. Most of the members of green algae have starch as stored food and some have oildroplet also.

3. One or more pyrenoids are also present in chloroplast as storage bodies. Pyrenoidscontain proten besides starch.

4. (i) Sexual reproduction may be isogamous, anisogamous or oogamous.5. (ii) Vegetative reproduction is by tragmentat asexual reproduction is by flagellated

zoospore produced in zoosporangium.Economic Importance:(1) Food -

(2)

(3)

(4)

Chlorella is used as food , because after Spirulina, Chlorella has largest amount of protein.Antibiotics -Chlorellin antibiotic is obtained from Chlorella.Space research -In space, Chlorella is used as a source of food and O by space travellers.Parasitic algae -Cephaleuros algae remains parasitically in the leaves of tea plant and causesdisease 'redrust'.

PHAEOPHYTABrown algae or sea weeds or "kelps"

Brown algae are found in marina water. Brown algae multicellular filamentous. Brown algae are the largest in size (upto 100 meter in length). Largest brown algae - Macrocystis The vegetative cell have a cellulosic wall usally covered on the outside by a gelatinous coating of align. Thallus of brown algae is divided into three parts:-

(i) Lamina (frond) - Leafy part or photosynthetic part(ii) Stipe - Elongated tubes celled trumpet hyphae are present for food con

(iii) Hold fast -e.g.

duction in stipe. Trumpet hyphae are analogus to sieve tubes ofvascular plants. Due to lamina and stipe brown algae look likeleaf (leafy algae).Help in attachment.Fucus, Dictyota, Ectocarpus

Reproduction :- Vegetative reproduction take place by fragementation. Assexual reproduction in most brown algae is by biflagellate zoospore.

Pigments :Chlorophyll - Chi 'a', Chi 'c’Carotene - Only caroteneXanthophylls - Mainly Fucoxanthin

Note : The amount of Fucoxanthin is more in brown algae due to which these algae are brown in colour.(Xanthophylls a!e mostly yellow but fucoxanthin is brown)

Stored Food :Laminarin and mannitol - both are derivatives of carbohydrates.

Phycocolloids : On cell wdll of brown algae some colloid substances like fucinic acid, alginic acid and fucoidin are

present which are known as phycocolloids. Phycocolloids protects brown-algae against dessication and shocks. Phycocolloids are used in ice-cream

as thickening agent. Alginates, salts of alginic acid used for dentury measurement. Alginates or Alginic acid - Obtained from Laminaria, Fucus, Macrocystis.

A1ginates are used in the manufacturing of soap, ice-cream, polish, cream and plastic.Special Point : (1) Life cycle of Ectocarpus and kelps are diplohaplontic, life cycle of Fucus is diplontic.

(2) Zoospores and gametes are pear shaped and have two unequal laterally attahced flane1la.(3) Sex repro. may be brown algae isogamous, anisogamous or

oogamons. Special Name :(1) Postelsia → It is known as sea palm(2) Anegclonema → It is old Ice bloom because it grows on marlae ice

It is known as Gulf weed because Sargssum is a free floating alga. It grows rapidly in North Atlantic oceanand covers thousands of hectare/of area. Therefore this region is called as sargasso sea.

Lominaria (Kelps) :It is called as Devil's Aprin.Iodine and Bromine - Obtained from Laminaria.

RHODOPHYTA

(1)

(2)(3)

(4)(5)

Red algaeRed algae are known as second ancient algae.e.g. PolysiphoniaThere is no motile stage found in life cycle of red algae and BGA i.e. cilia & flagella are absent.Red algae mainly found in marina water with greater concentration found in the warmer areas. Butexceptionally Batrachospermum is found in fresh water (rivrer) and Porphyridium is found on land.Red algae are multicellular but exceptionally Porphyridium is unicellular.Cell wall of red algae is complex and made up of cellulose & pectin.The cell wall of red algae is also complicated like blue green algae. Their cell wall has many differenttype of substances such as xylan, galactose, polyuronic acid, polysulphate esters.

But in some algae calcim carbonate is also present in the cell wall. Due to which their thallus become stony. These algae from lime stone & coral reefse.g. Corallina and Lithothamnion

Pigments:Chlorophyll - Chl' a' and chl 'b'Carotenes - B carotenePhycobilins - R - phycoerythein (red coloured) and R- phycocyanin (blue coloured)(1)(2)(3)

On the basis of pigment red algae is similar to blue green algae.Colour of red algae changes according to depth in sea this is celled as Gaudikov's effect. When red algae are present on the sea their colour is blue and when they are at the botton their

(4)(5)

colour is red.At the surface of sea the amount of R-phycocyanin is more while in depth the amount R-phycoerythrin is more.Penetration power is maximum in ultra violet and violet light. R-phycocrythrin is only pigment to absorbult violet light. Due to phycoerythrin red algae are deepest algae.Gaudikov's effect is also found in Blue- Green algae.Red algae not always red, it may be blue coloured also.eg. Batrachospermum - This is a blue coloured algae.

Stored Food :Floridean starch - floridean starch is structurally similar to glycogen and amylopectin

Phycocolloids :Agar -Agar, carrageenin and funori phycocolloids are found in the cell wall of red algae.

Reproduction :(1) Vegetative - By fragmentaiion(2) Asexual - Non motile spores [By monos pore, carpospores, tetraspore](3) Sexual reproduction :

(i) By zygotic meiosis because main plant is haploid.(ii) Sexual reproduction is oogarmous and accompanied by complex post fertilizationdevelopments.(iii) The female sex organs are called carpogonia.(iv) The maie sex organs of red algae are known as spennatangia. Non moiile spore like gametesare formed in spermatangia which are known as spermatia.(v) Life cycle of Polysiphonia is diplobiontic and Batrachospermum is haplobiontic

Special points and Economic importance(1)(2)(3)

Harveyella - It is a colourless parasitic alga. It remains as parasite on other alga.

Porphyra - It is an edible algae.

Gelidium and Gracilaria - Agar - Agar colloid is obtained from these. It is used to prepare culturemedium to grow microbes and in prepartion of ice creams and Jellies.

(4) Chondps crispus - It is also called Irish moss, Carrageenin colloid is obtained from this alga. It is used

as gelating agent in food industries (i.e. to make the food item viscous)

Capsule of medicines is also prepared from carrageenin.

HABITAT OF SOME IMPORTANT ALGAE(1) Terrestrial - The algae found in moist soil & wall.

eg. Terrentofolia

(2) Epiphytes - Algae which are present on plants

eg. Protoeoceus

(3) Endophytes - Algae which are present inside plantsego

eg. Coieochaete niteiurn (in Nitella plant)

(4) Epizoic - Algae which are present on animalsego

eg. Cladophora (present on Mollusca shell)

Cyanoderma and Triehophilus (Blue green algae) (Present on sloth bear)

(5) Endozoic - Algae which are present inside the body of animals

eg. Zooehlorella and Zooxenthellae (inside the Hydra)

(6) Parasites - Algae that live as parasite and causes diseases

eg. Cephaleuros (algae remains in the leaves of tea plant)

Cephaleuros causes red rust disease of tea

(7) Thermophilic -Algae found in hot water.eg. Chlorella

(8) Cryophytes - Algae which are pre~ent in polar regions & Low Temperature.eg. Chlamydomonas (some species)

Haematdcoccus nivalis (It develops red snow in polar region.)

(1)

(2)

(3)

(4)

(9) Epiphloephytes - Algae arise on bark of trees.

THALLOPHYTAThe term "Thallophyt.a" was given by “Endlicher” According to two kingdom c1assification all

the algae, fungi and prokaryotes were placed in thallophyta, because their pant body is thallus.

In thallophyta the male sex organs are called as Antheridia and female sex organs are called as Oogonia.

Sex organs are unicellular & Jacket less [Jacket -layer of sterile cells)

The sexual reproduction in thallophyta is isogamous, anisogamous and oogamous.In thallophyta, sexual reproduction takes place through zygotic meiosis, therefore embryo is not formed.

Demerits of Two kingdom classification:(1) In two kingdom classification Prokaryotes and Eukaryotes placed in the same group.

(2) In this system photosynthetic green algae and non photosynthetic fungi are placed in same group i.e.

plantae.(3) In two kingdom system unicellular and multicellular organism are placed together.

(4) On the basis of cell wall bacteria were considered as plant and put in plantae.

(5) Position of Euglena is not fixed.

BRYOPHYTA

The term "Bryophyta" was Proposed by "Robert Braun".

The study 0f Bryophytes is knovjn.CIS Bryology.

Hedwig is considered to be the father of Bryology. But according to some scientist it is believed that

Cavers is the father of Bryology.

Father of Indian Bryology is Prof. Shiv Ram Kashyap.

General characteristics :

1. Bryophytes are the first land plant It is believed that, they originated from aquatic plant and they comeon land through water. Because some bryophytes have characters similar to aquatic plants (eg. presenceof air canal)

2. Bryophytes are known as amphibians of the plant kingdom, because these plants can live in soil but aredependent on water for fertilization.

3. Bryophytes are not considered as the successful land plants because vascular tissue is absent and theyneed water for fertilization. Due to the absence of vascular tissue bryophytes can not grow very tall. Theprocess of water conduction in bryophytes takes place with the help of parenchyma. Parenchyma is aliving tissue.

4. Plant body of bryophytes is more differrentiated than that of algae.5. Bryophytes are sciophytes, i.e. bryophytes.prefer to grow in most (wet) and shady places.6. It is thalluslike & prostrate & erect & attached to substraction by unicellular or multicellular rhizoids.7. They lack true roots, stemsor leaves. But they may root like, stemlike or asses leaf like structures.Life cycle of Bryophytes:1. The main plant body of bryophyte is haploid. It produces gametes, hence is called gametophyte.2. Sex organs are formed on gametophyte Sex organs are multicellular and facketed in bryophytes male sex

organs are called as antheridium and female sex organs are called as archegonium. Archegonium is flaskshaped.

3. The male gametes of bryophytes are motile. These motile male gametes are called as antherozoids.

Antherozoids are usually comma shaped and biflagellate. Female gamete is called egg.

Buds(n)

Protonema(n)

GerminationMosses

Spores(n)

Sporic Meiosis

Spore mother cells(2n)

Sporophyte (2n)

Embryo(2n)

Liver worts&

Horn worts

Gametophytic generation

GAMETOPHYTE(n)

Antheridia(n)

Archegonia(n)

Antherozoids(n)

Egg(n)

Zygote(2n)

MitosisSporophytic generation

4. In Bryophyta, fertilization is performed by zoodiogamy i.e. male gamete swims into water to reachethe female gametes and fertilizes it.

5. Oogamous types of ferlilisation is four:d in bryophytes. As a result of the teli:lization, a diploid zygoteis formed. Zygute does not undergo reduction division (meiosis) immediately) This zygote initiatesthe sporophytic generation. Sporophytic generation is a diploid stage.

6. Zygote formed embryo and then sporophyte by mitosis. Sporophyte of bryophyte is not differentiatedinto root, stem & leaf but it is made of foot Seta & capsule so it is known as sporagonium.Sporophyte is not free living attached to photosynthetic gametophyte & derived nocrishment from it.

7. The germination of spores is direct or indirect. In Liverworts & Hornworts the germination of spore

is direct i.e each spore forms a gametophyte after germination i.e. each spore forms one thallus.

Bur the germination of spores in Mosses is indirect. In mosses a multicellular filament is formed after

the germination of spore. This filament is known as protonema. Now buds are formed on protonema.

Each bud develops and form a gametophyte plant. Indirect germination is best for survival. Mosses

are gregarious in nature because they appear in group.

Note: Protonema developed from spores is called as primary protonema and the protonema

developed from parts other than spores are known as Sometimes buds again produce multicellular

filamentous structures when is secure Protonema.• Sexual reproduction in bryophytes is oogamous type and life cycle is halplodiplontic type.• In Bryophyta the sporophyte is depend on gametophyte. This is a unique character of

bryophyta.

Bryophyta is divided in to three classes

1. Hepaticopsida 2. Anthocerotopsida 3. Bryopsida or Musci

HEPATICOPSIDA - LIVFR WORTS

(i) All the bryophytes included in this class have shape like liver (eg. Marchantia) or flat (eg. Riccia) so theyare known as liverworts.

(ii) Plant body of this group is thallus like and dorsiventral. Rhizoids and scales are present on thallus..Rhizoids are unicellular and unbranched. Scales are multicelluler.

(iii) The leafy members (eg Porella) have tiny leaf like appendages in two rows on the stem like structures.(iv) The sporophyte of Liverworts is completelydepend on gametophyte i.e. it is d~pehd on gametophytes

food, water and habitat.(v) The sporophyte of Liverworts is made up of foot, seta and capsule. (Except Riccia sporophyte is made

up of only capsule).(vi) In capsule of Riccia some diploid & sterile cells are there to provide nutrition to developing spores, they

are known as nurse cell.(vii) These nurse cells are further evolved into elastic Marchontier. Elastaters are hygroscopic & they help in

dispersal ofEg. of Liverworts -

Ricca, Marchantia, Cryptothallus, Riella, Pellia, Porella.Note : (1) In Bryophytes. sporophyte of Riccia is the simplest.

(2) Asexual (vegetative) rcproduction in Liverworts takes place by iragmentation of thalli, or by theformation of specialised structures called gemmae (sing. gemma). Gemmae aregreen. multicellular.asexual buds, which develop in small receptacles called gemma cups located on the thalli. Thegemmae become detached from the parental body and germinate to form new individuals. Eg.Marchantia.

(3) During sexual reproduction male and female sex organs are produced either on same (eg. Riccia)or on different thallus (Eg. Marchantia)

ANTHOCEROTOPSIDA - HORNWORTS

(i) The plant body of this group is also thallus like. Scales are absent but rhizoids are present on thallusRhizoids are unicellular and unbranched.

(ii) The sporophyte of Hornworts is divided into foot and capsule.(iii) The sporophyte of Homworts is not completely depend on its gametophyte i.e. it is semiparasite because

its sporophyte is photosynthetic therefore it can manufacture its own food. So it does not depend ongametophyte for food, it depends only for water and habitat.

(iv) In hornworts at the basal part of capsule, a special, type of meristem is present. Due to the activeness ofthis meristem, the capsule grows rapidly. It grows like the hom of animals.eg. Notothylus, Anthoceros

BRYOPSIDA OR MUSCI -MOSSES

(i) All the Mosses are included in this class. The plant body of mosses is made up of stem like. leaf like andrhizoids (roots like). The Rhizoids present in the plants of this class are multicellular. branched andobliquely septate.Note - The presence of leaves in gametophyte is the unique character of Moss because in plant kingdomany gametophyte do not have leaves. They consists of upright selender axis bearing spirally arrangedleaves.

(ii) Vegetative reproduction in mosses is by fragmentation and buding in the secondary protonema. Duringsexual reproduction, sex organs are produced at the apex of the leafy shoots.

(iii) The sporophyte of moss in bryophyta is highly developed while the sporophyte of liverwort is the sim-plest. The sporophyte of moss is divided into foot, seta, capsule.

(iv) The sporophyte of mosses is also semiparasite like, that of Hornworts. i.e. it is photosynthetic. The moseshave an elaborate mechanism of spore disperal.Eg. of Mosses: Funaria - Rope moss or Cord moss Polytrichum - Hair tap moss Dawsonia - Australian moss -The highest bryophyte-45 cm. Buxbaumia - Saprophytic moss - Photosynthesis absent Sphagnum -

– Bog moss - lt like.s to grow-on acidic bog.Quaking bog

– Carpet moss or Turf moss - It spreads like a carpet on bog due to which, the swampcannot be easily seen.

– Peat moss - It is a fossil fuel that obtained from bog. The formation of peat takes place bythe fossilization of Sphagnum. Sphagnum grows in acidic bog. The number of bacteriaare less in bog due to which the degradation of dead cell could not takes place. Hence it ispresent in the form of fossil.

– Absorbent cotton - Sphagnum can absorb water in very high amount, therefore it is usedin the form of absorbent cotton in Europe.

IMPORTANCE OF MOSSES

– Bryophytes in general are of little economic importance but some mosses provide foodfor herbaceous mammals, birds and other animals, Species of Sphagnum, a moss, providepeat that have long been used as fuel, and because of their capacity to hold water aspacking material for transshipment of living material. Mosses along with lichens are thefirst organisms to colonise rocks and hence, are of great ecological importance. Theydecompose rocks making the substrate suitable for the growth of higher plants. Sincemosses foml dense mats on the soil, They reduce the impact of falling rain and preventsoil erosion.

PTERIDOPHYTATerm pteridophyta was proposed by Haeckel.

The study of pteridophytes is known as pteridology.Pteridophytes are known as reptiles of plant kingdom.

1. Pteridophytes are also called as vascular cryptogames. Pteridophytes are vascular plants i.e. xylemand phloem are present in it. In pteridophytes, vessels in xylem and companion cells in phloem areabsent. But exceptionaly xylem of Pteridium, Selaginella and Marsilea contains false vessels.Note :-Secondary growth is absent (due to absence of cambium) in pteridophytes butexceptionally secondry growth is present in stem of Isoetes.

2. Pteridophytes are used for medicinal purpose and as soU binders. They are also frequently grownas ornamentals.

3. Pteridophytes are called as the first successful terrestrial plants i.e. they are more adapted terrestrialplants as compared to bryophytes.

4. Because like bryophytes, most of the pteridophyte plants growin shady & moist places.(i) Vascular tissue is present in pteridophytes.(ii) The  y have roots.

5. Pteridophytes are not completely successful terrestrial plants because they need water forfertilization, so pteridopl)ytes grow in shady and m6ist places.

6. In pteridophyta, the plant body is completely differentiated in to root, stem and leaves. The primary root remains a1ive for short period. After some time it is replaced by adventitious

roots. Stem is erect or prostrate. When in pteridophytes stem is underground, which is known as

rhizome. On the basis of leaves. pteridophytes are of two types -

First in which stem is smaller while leaves are larger. They are known as macrophyllousPteridophytes.

eg. Pteridium, Pteris, MarsileaSecond, in which stem is larger and leaves are smaUer. They are called as microphyllousPteridophytes.

eg. Equisetum, Lycopodium, Selaginella

LIFE CYCLE OF PTERIDOPHYTES

Plant is sporophyte. Le. diploid.Most of the pteriophytes are homosporus i.e. only one type of spores are formed during reproduction.

eg. Psilotum, Lycopodium, EqtJisetum, Pteridium, Dryopteris, Adiantum, Pteris.Exception - Some pteridophytes are heterosporus i.e. two types of spores microspores and megaspores.

eg. Selaginella, Isoetes, Marsilea, Salvinia, Azolla, Stylites, PiI1ularia, RegnellidiumFormation of spores takes place in sporangia. Sporangia are formed at the abaxial surface of leaves. Theleaves on which sporangia are formed are called sporophylls (reproductive leaves) and normal photosyntheticleaves are called tropophylls (vegetative leaves). Sporangia are present in groups, these groups are calledsorus (Plural-sori). Sori are found on sporophylls.

Note:In pteridophyta, sporophylls are also photosynthetic. This is a unique character of pteridophyta.

Spore mother cells are present in sporangia. Spores are formed in these spore mother cells by meiosis andthese spores start the gametophytic generation.6. In pteridophyta, the germination of spores is exosporic i.e. germination takes place out side the

sporangia (in soil)7. In soil a gametophyte is formed by the germination of each spore. which is known as prothallus.

The formation of garnetophyte takes place in the soil tnerefore it is free (independent) and mostlyphotosynthetic. These gametophyte require cool, damp, shady places to grow. Because of thisspecific restricted requirement and the need for water for fertilisation, the spread of livingpteridophytes is limited and restticted to narrow geographical regions.

8. There is no relation between the main sporophytic plant and prothallus. Prothallus (gametophyteplant) is made up of thallus and rhizoids. It is non vascular.Note: In plant kingdom, gametophyte is always non vascular

9. In homosporus pteridophytes gametophyte is monoecious but in heterosporus pteridophytes thegametophyte is dioecious.

In heterosporus pteridophytes -Microspores form - Male gametophyteMegaspores form - Female gametophyte

10. The formation of sex organs takes place on this gametophyte. Male sex organs are called asantheridium and female sex organs are called as archegonium. The formation of male gametestakes place in Antheridia which are called as antherozoids.Antherozoids are spiral and multiflagellate but exceptionaly antherozoid of Selaginella are spindleshapes and in Lycopodium is curved (comma) and biflagellate. Egg is formed in archegonium.

11. Fertilization takes place by zoodiogamy and zygote is formed as a result of fertilization. Zygotedevelop and forms an embryo. Now this embryo develops and forms a sporophytic plant withroot, stem, leaf. Type of sexual reproduction in pteridophyta is oogamous. Their life cycie is diplo-hapiontic type. The unique character of life cycle of Petridophyte is - independent alternation of generation

i.e. sporophyte and gametophyte are independent of each other.

Embryo(2n)

Zygote(2n)

Fertilization(Zoodiogamy)

Egg(n)

Antherozoids(n)

Sporophyte (2n) Sporophylls

(2n)

Sporangia(2n)

Spore mother cells(2n)

Spore(n)

Gametophyteor Prothallus

(n)

Antheridia(n)

Archegonia(n)

Meiosis

Sporophyticgeneration

Gametophyticgeneration

Pteridophyta is divided in to 4 classes1. Psilopsida 2. Lycopsida 3. Sphenopsida 4. Pteropsida

1. Psilopsida:(i) The most ancient vascular plants are placed in this class. The plants in this class have many

primitive characters.(ii) Their plant body is differentiated in to stem (rhizome), scaly leaves and rhizoids.

2. Lycopsida:(i) Club mosses are placed in this class.(ii) The plant body of club mosses is differentiated into root, stem and leaves. Leaves are green and

photosynthetic and known as tropophylls are present on stem. Roots are adventitious.Lycopodium - Common club moss or Ground pine or Trailing evergreen

It is a medicinal plant. It is used as tonic in Homeopathic medicines.Selaginella - Little club moss or spike moss or Bird's nest moss or Resurrection plant.Selaginella bryopteris - It is known as "Sanjeevani"

3. Sphenopsida(i) In this class Horse tails are included.(ii) The plant body of horse tails are differentiated into root, stem or rhizome & scaly leaves.(iii) Roots are adventitious.(iv) Their stem is jointed i.e. nodes & internodes are clearly seen on stem. Scaly leaves are present on

these nodes.(v) Silica is present in the epidermis of stem and leaves. Due to silicated surface leaves become

rough. If two horse tail plants collide , then there is a dangerous chance of fire in the forest.(vi) The formation of sporangia takes place on special branches of stem called as sporangiophores.

Sporangiophores are arranged in a group and fonn a long and condensed cone. This cone is formedat the apical part of aerial stem

e.g. Equisetum (pipe)

Pteropsida :(i) This is the largest group of pteridophytes.(ii) They are commonly called as ferns. Most of the pteridophytes are ferns.(iii) Ferns are megaphyllous (macrophyllous)·i.e. rhizome is small and leaves are tompartively larger

and these leaves are known as 'Fronds'.(iv) Multicellular hair are present on the young leaf and young rhizome of fems which are called as

ramenta. They are for protection & to decrease the loss of water during transpirations.(v) There is no difference between tropophylls and sporophylls in fern i.e. every leaf of fem forms

sporangia at the time of reproduction. Therefore cones are not produced in ferns.Pteridophyta - 4 classes

(1) PSILOPSIDA(i) Psilopsida are root less pteridophytes Rhizoids are present instead of roots. In psilopsida stem is

underground i.e., Rhizome. This rhizome bears some aerial branches. Sporangia are formed onthese branches. Rhizoids are found on rhizome also.

(ii) Scaly leaves are present on aerial branches (scaly leaves - dry, brown coloured & non-photosynthetic.They are only for protection of sporangia)

(iii) Scaly leaves do not have capacity of photosynthesis, therefore photosynthesis is performed by stem.(vi) Sporangia are formed on stem.(v) Sporangia are formed on stem.(vii) Most of the plants in this class are extinct only one living genus are present in this class - Psilotum

Psilotum Aliving fossilRhynia & Horneophyton - Fossil plant

(2) LYCOPSIDA(i) Sporangia are formed on sporophylls. These sporophyll are not scattered on stem, instead they are

present in groups at the tip of plant. The group is called strobilus or cone.Isoetes - Quill wort or Merlyn grass - Aquatic weed.Selaginella - Resurrection plant - Most of the species of selaginella are “Draught Escapers” i.e., do notface draught condition, complete their life cycle in short wet season. In dry season plant dries & rolls in aball like structure. In this stage, it passes out dry season. When wet season returns plant absorb water 4again becomes normal green plant. So it is termed as “Resurrection Plant”.

SOME IMPORTANT POINTS1. Heterospory (Heterosporous Condition) :-

Occurence of 2 type of spores, small (Microspore) & large (macrospore = megaspore) is heterospory. Avery few genera are heterosporous in pteridophytes eg. Selaginella, Salvinia, Azolla.

2. On these plants microspores form malegametophyte, male sex organ 4 malegamete which come outsidethe microsporangium but the megaspore forms female gametophyte, female sex organs & female gameteinside the magasporangium on the parental sporophyte which are retained in megasporangium for vari-able periods.

3. After the fertilization zygote & embryo is formed. Embryo essentially come outside the megasporangiumso seed could not be formed in pteridophytes but the heterospory is found in them which is an importantstem in evolution of seed habit in higher plants.Note : In some pteridophytes prothallusis saprophytic & heterosporus petridophyte like selaginella &salvinia gametophyte are not called prothallus.

Examoles of Ferns :Pteridium pteris - They are called “Braken ferm” or “Sun fem”.

Dryopteris - Also called as Brook shield fem

Adiantum - Walking fernThis name is given to them due to rapid vegetative reproduction . Vegetative

reproduction in Adiantum takes place by means of leaf tip, It spreads

very fast.

Osmunda - Royal fern or flowering fern.

Ophioglossum - Adder's tongue fern

Marsilea - Pepper wort fernAzolla - Aquatic fern (Smallest pteridophyte and biofertilizer)

Alsophila - Tree fern (Largest pteridophyte)

Salvinia - Aquatic is nature

SOME IMPORTANT POINTS :(2) Selaginella and Salvinia In heterosporus pteridophyts Selaginella and Salvinia and the development

& Azollaof the zygote in to young embryos takes place with in the femalegametophyte. Female gametophytes are retained on the parent sporophyte

for variable periods.

Genera like Selaginella and Salvinia posses partially endosporic

development of embryo.

This event is a precursor of seed habit considered an important steps in

evolution.(3) Selaginella Ligulate leaves (tongue shaped) are present in it.

Function - Ligule is secretory structure, which secretes water and keso

the sporangium and the young leaf moist.

(4) In some pteridophytes sporangia are not formed on lower surface of sporophylls-

In some pteridophytes sporangia are formed at the axil of leaf.

eg. SelaginellaIn some pteridophytes sporangia are formed in spike.

eg. OphiglossumIn some pteridophytes sporangia are formed in sporocarp.

eg. Marsilea, Azollo, Salvinia(5) In some pteridophytes prothallus is saprophytic and the heterosporus pteridophytes like Selaginella and

salinir gametophytes are not called prothallus.

GYMNOSPERM(1) Term gymnosperm was proposed by “Theophrastus”.(2) The gymnosperms (gymnos = naked. sperma = seed) and plants in which the ovule are not encloded by

any ovary wall and remain exposed, both before:and after fertilization.(3) Study of Gymnosperm known as Gymnospermology.

Main plant body of Gymnosperm is divided in to Root, Stem and leaves. The roots are generally tap roots.

Note:- Roots in some genera have fungal association in the from of mycorrhiza (Pinus), while insome others (Cycas) small speciallised roots called coralloid roots are associated with N2-fixingcyanobacteria.

The stems are unbranched (Cycas) or branched (Pinus, Cedrus). The leaves may be simple or compound. In Cycas the pinnate leaves persist for a few years. The leaves in gymnosperms are well-adapted to extreme condition. In conifers the needle like leaves reduce the surface area, their thick cuticle and sunken stomata

also help to reduce water loss.Gymnosperm & Angiosperm are collectively included under spermatophyta i.e. seed bearing plants.

Gymnosperms are naked seeded plant i.e. no fruit formation takes place in these plant.

In gymnosperm embryo & seed formation takes place but no fruit formation occur.

Gymnosperms are very limited in distribution. They are mainly found in cold regions.!n India Gyrrmospermsare found on Himaliayan mountains. They usually OCOlr on slopes of mountain in cold region thereforegymnosperms are xerophyte.

All gymnosperm are vascular plants. Therefore vascular tissue presenU.e. xylem & phloem. Xylem lackvessels & phloem lacks companion cells.Note :- Exceptionally in xylem of Gnetum, Ephedra, Welwitschia true vessels are present. Secondary growth takes place in gymnosperms stem, so Gymnosperms stem is woody.Most of the gymnosperms are arborescent (woody and tree habit) -but some are present as shrub.

eg. EphedraSome Gymnosperm are liana or woody climbers.

eg. Gnetum ula

LIFE CYCLE OF GYMNOSPERM

1. In Gymnosperms main plant body is sporophyte (diploid). All Gymnosperm are dioecious. i.e. male &female plants are separate, but exceptionally Pinus is monoecious.

2. All Gymnosperms are heterosporus. Atthe time of reproduction two types of spores are formed. Microspores form - Male gametophyte Megaspores form - Female gametophyte

3. These two types of spores are formed in different sporangia. Microspores are formed in Microsporangia. Megaspores are formed in Megasporangia. Integumented megasporangia are also termed as ovule.

4. Both types of sporangia are formed on different sporophylls. Microsporangia are formed on Microsporophyll. Megasporangia are formed on Megasporophylls.

5. Both types of sporo:hyllS are)ound in groups & form male cone (strobilus Microsporangiate) & femalecone(Macrosporangiate).

6. Meiosis takes place in cells of microsporangium & megasporangium and form microspore & megasponerespectively.

7. In Gymnosperm and angiosperm germination of spores is endosporic i.e. germination of spore takesplants with in sporangia.

8. Male gametophyte is formed after germination of microspore. Male gametophyte is.also known as pollengrain. Male gametophyte forms male gamete.

9. In lower gymnosperm, male gametes are motile & muiticiliate, but in higher gymnosperm and angiospermmale gametes are non motile due to the absence of cilia and flagella. They do not require water forfertilization. Main body of ovule is made of a diploid tissue called as nucellus. A cell of nucellus acts as megaspore mother cell which undergoes meiosis and forms four haploid

megaspores, out of which only one remains functional and rest three degenerate. This megaspore further develops into female gemetophyte or endosperm. The cells of female gametophyte or endosperm behave like arcegonial initial and form two or

more archegonia. Archegonia - It forms egg.

10. Pollen grains (Male gametophyte) reach at the micropyle of ovule by wind, called as anemophilly. Afterpollination malegametophyte (pollen grains) are stored in the pollen chamberof ovule .

FERTILIZATION :-Two types of fertilization take place in gymnosperms

Zoodio - siphonogamy - This type of fertilization occurs in 1ower gymnosperms. Male gametes aremotile and transfered to female gamate by pollen tube.

Siphonogamy - This type of fertilization occur in higher gymnosperms. Male gametes are non motiletransferred to female gamete (egg) by pollen tube. After Pollination male & female gametes are fused &form a diploid zygote.

In gymnosperm single fertilization takes place so only zygote is formed through fertilization. InAngiosperm double fertilization takes places so two product are formed after it (i) Zygote(ii) Endosperm.

In gymnosperm, endosperm is formed before fertilization by megaspore so it is haploid but inangiosperm endosperm is formed after fertilization by triple fusion (sec. nucleus (2n) + malegamete (n). So, endosperm of angiosperm is triploid.

In angiosperm, fertilization take place by siphonogamy. Gymnosperm + Angiosperm = Siphonogama

[LIFE CYCLE OF GYMNOSPERM]

DEVELOPMENT OF ZYGOTE -(1) Embryo is lormeo by the development of diploid zygote. After embryo formation ovule is changed into

seed. Embryc enclosed in ovule because i:ievelopment of spore is endosporic. Seeds are not formed in pteridophyta because germination of spore is exosporic i.e. embryo

develops outside the sporangia.Embryo is enclosed in seed. Seed absorbs water & bursts. Now embryo germinates and forms a newdiploid plant.Note :- Different types of polyembryony are found in gymnosperm i.e. in single seed more than oneembryos are produced.

Sporophyte (2n) Sporophyte (2n)

Male cone (2n) Female cone (2n)

Microsporophylls (2n) Megasporophylls (2n)

Microsporangium (2n) Megasporangium (Ovule) (2n)Meiosis in microspore mother cells Meiosis in megaspore mother cell

Microspores (n) Microspores (n)

Male gametophyte (Pollen grain) (n) Female gametophyte (n) (Endosperm)

Male gametes (n) Archegonia (n)

Female gamete (egg) (n)

Germination Germination

FertilizationBy

Zoodio-siphonogamyOR

Siphonogamy

Zygote (2n)

Embryo (2n)Mitosis

Seed

Sporophyte (2n)

Diploid

Diploid

Haploid

LIFE CYCLE :Life cycle of Gymnosperm & angiosperm is diplontic because gametophytic generation is shortlived. Gametoohvte is verv reduced & depends on its sporophyte.SOME IMPORTANT POINTS :1. Antheridia is absent in gymnosperm & angiosperm i.e. pteridophyte is last group having antheridia.

But archegonia is also absent in angiosperm. So gymnosperm is last group having archegonia.2. During evolution Gametophyte becomes reduced & sporophyte becomes well-developed.

Very reduced - In AngiospermGametophyte

Wall developed - In MossVery reduced - In Thallophyta (Only zygote)

SporophyteWall developed - In Angiosperm

Gymnospenns are divided intotwo groups(1) Cycadophyta (Lower Gymnosperm) (2) Coniferophyta (Higher Gymnosperm)

CYCADOPHYTA(A) The plants of this group are megaphyllous or macrophyllous with circinate vemation.(B) Presence of Ramenta.(C) Male gamete is motile.

Cycadophyta is divided into three ordersCycadofillicales or Pteridospermae:-

(i) This order is completely extinct. Plant of this order known as seed fern.eg. Lyginopteris - Fossil plant

(ii) Cycadofillicales was the first group of seed plant.Benettitales :-

(a) It is also a completely extinct group.eg. Williamsonia - fossil plantNote : Its fossils were discovered by Prof. Birbal Sahani

(iii) Cycadales :(a) Presently living cycadophytes are included in this order.(b) All the plants of this group are living fossils.

Zamia pygmea - Smallest Gymnosperm Cycas - Fern palm or Sago palm

Sago is obtained from its stem. Cycas thouarsii - The diameter of its ovules is 7 cm. Its ovule, male gametes, egg

and male cone are largest in plant kingdom. In embryo of cyeastwo cotylesons are present. In cycas male gamates are top shaped.In Cycas female cone is absent.

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CONIFEROPHYTAFour orders are included in this group

(i) Ginkgoales :-(a) It is the oldest order of coniferophyta. Maximum plants of thi group are extinct.

Ginkgo biloba - living fossil - It is also kown as “Maiden hair tree”Note : Exceptionally Ginkgo biloba belongs to higher gymnosperm but its male gametes aremotile.

(ii) Cordaitales :-(a) It is completely extinct group

eg. Cordaites

(iii) Coniferales :(a) Conifers are included in this group.(b) It is the largest group of gymnosperm

Examples of Coniferales -(a) Pinus (Pines) :-

Pinus species - A resin "turpentine" is obtained from it. Turpentine isused in varnish.

Pinus gerardiana - It is known as "chilgoza pine" Pinus roxburghii - It is known as "chirpine".

(b) Cedrus deodara - It known as devdar(c) Taxus - It is known as Yew tree. An anticancer medicine “Taxol”

is obtained from its bark.(d) Taxodium maxicanus - The stem of this plant is thickest in the plant kingdom.(e) Abies balsamea - A resin “Canada balsam” is obtained from it. It is used

manufacture permanent slides in biology laboratory.

(f) Juniperus virginiana - An oil is obtained from this tree - “Cedar wood oil”. It isused cleansing fluid in biology laboratory. This oil isalso used microscope to increase the resolving power.This oil is used nail polish remover.

(g) Araucaria species Araucaria excelso - Christmas tree

Ornamental plants Araucaria araucana - Monkey puzzle tree

(h) Sequoia species - The plants in this genus are heavy. Therefore they arecalled as father of forest.

Sequoia giganteum - It is called Red wood tree or Sherman tree. It is the largestgymnosperm. There is only one tree of this species andthat is in California (America)

(i) Metasequoia - It is a living fossil. This plant is present in china valley.

(iv) Gnetales -(a) They are the most advanced gymnosperms.(b) Exceptionally members of this group have vessels in xylem.(c) Archegonia is absent in the members of this group.eg. (1) Gnetum (2) Welwitschia

(3) Ephedra - Exceptionally archegonia is present in Ephedra.Ephedra - This gymnosperm is commonly found in Rajasthan. Ephedra is a medicinal plant. Ephedrine(Medicine)is obtained from it. It is an effective medicine in asthma. Athletes misuse it, so ephedrine is restricted for them.

Cycadofillicales were first seeded plants. First time seed habit was established in this group. In general way seedhabit was originated from those pteridopbytes which are now extinct. These pteridophytes were ancestor ofcycadofillicales.

Some heterospones pterldophyes Selaginella and Salvinia show origin of seed habit.

There is mainly two requirements for seed formation.

(1) Plant should be heterosporus (2) Germination of megaspore should be endosporic