LEVEL OF ORGANISATION OF CELL IN BODY

* all members of animalia are multicellular and they exibit different level of organisation.
*cellular level-in sponges the cell are arranged in loose aggeregation.
   tissue level- in coelentrata the cell arrangement are more complex. here, the cell performing the                             same function are arranged into tissue.
   organ level-in platyhelminthes the tissue are grouped together  to form organs. each organ                                       specialised for a particular function.
   organ system level-in animals like annelida,arthropods,mollusca,echinodermata and                                               chordates,organ are associated to form funtion system. each system concern with a                              specific physiological function.this is called organ system level.
*in organ system level, the organism are classified on various basis like open and close circulatory system, complete and incomplete digestive system etc.

ALTERNATION OF GENERATION IN PLANTS

Different plant group complete their life cycle in different patterns, e.g.- angiosperm complete their life cycle in two phases- a diploid sporophyte  plant body and the other haploid gametophyte, the two follow each other rigidly. this phenomenon is called alternation of generation.
   
     Life cycle of other plant group can be of following patterns-
1. Haplontic- there is a single vegetative individual or somatic phase. it is haplod and it is often called gametophyte. the haploid plant body may be unicellular, colonial or multicellular.

2. Diplontic- there is a single somatic  phase or vegetative individual. it is diploid  and is often called sporophyte though it produces gametes in its body or sex organ.

3.this type of life history involves the  sequential recurrence of two well developed somatic phase or vegetative individuals, gametophyte and sporophyte. the sporophyte. the sporophyte possess  diploid chromosome number(2n). meiosis takes place in it at the time of formation of  meiospors. the haploid meiospores germinate to produce haploid gametophyte. the gametophyte produces gametes.fusion of gametes produces zygote which develops in sporophyte. this is called alternation of generation.

ANGIOSPERMS

* the sporophylls are aggeregate to form flowers, angiosperm are also called flowering plant.
*the pollen grain and ovule develops in specialised structure called flower.
*the seeds are enclosed by fruits.
*it has wide range of habitat, except sea because only two species are found there ZOSTERA and THALASSIA
*they range in size from tiny ,almost microscopic WOLFIA to tall tree of EUCALYPTUS
* pollination is through several agencies but most prominent is by insects.
*pollen reach stigmatic surface found at the tip of the carpell.
*female gametophyte develops upto 8 nucleate stage.
*archegonia are absent . instead there is one oosphere surrounded by two synergids that attracts and bring the pollen grains.
*there is double fertilization. one produces embryo,or new sporophyte, the other forms primary endosperm cell.
*endosperm is formed through triple fusion and generally triploid.
*fertilized ovules ripen into seeds. the seeds are covered by fruit. a fruit is technically a ripened ovary.
*xylem contains vessels.
*phloem possessses sieve tubes and companion cells.*secondry growth occurs in stem and root of some angiosperm, placed in group dicots.
*angiosperm are divided  into two sub-groups-
   1. dicotyledonous
   2. monocotyledonous

1. dicot-it is characterised by the presence of two cotyledons in seed,
                generally reticulate venation in leaves,
                concentric tissue in the stem with open vascular bundle arranged in a ring,
                penta or tetramerous flowers.
                e.g.- pea, rose, mulsard, eucalyptus etc

2. monocot- it is characterised by the presence of single cotyledons in seed.
                    generally parallel venetion in leaves
                    scattered closed vascular bundle in stem
                    trimerous flower
                    e.g.- banana, cereals, palms,grasses, bamboo etc.

GYMNOSPERMS

*gymnos means naked and sperma means seed, hence gymnosperm are those plants in which the ovules are not enclosed by any ovary wall.
* it includes medium size trees,tall trees and shrubs.
*SEQUOIA is the tallest tree among gymnosperm.
*it generally posses tap root
*PINUS root has association of fungus called mycorrhiza
*CYCUS root is coralloid and has association with cyanobacteria which helps in nitrogen fixation.
*stem are unbranched in CYCUS and branched in PINUS,CEDRUS.
*leaves may be simple or compound.
*in conifers , the needle like leaf reduce the surface area, their thick cuticle and sunken stomata also      help to reduce water loss.
*gymnosperms are heterosporous, they produce microspore and megaspores.
*spores are produced within sporangia that are borne on sporophylls, which are arranged spirally        along an axis to form lax or compact or strobili or cones. *the cone bearing microsporophylls and microsporangia are called male strobili.
* male strobili produces pollen grain
*the cone bearing megasporophylls and megasporangia are called female strobili.
* in PINUS , male and female cones develops on same tree.
*in CYCUS,male and female cones develops on different tree.
*megaspore mother cell(MMC) differentiate from one of the cell of nucellus, nucellus is protected by ovule, the ovule clustered to form female cone. this MMC develops 4 megasporangium one of which develops into multicellular female gametophyte bear two or more archegonia or female sex organ.
* male and female gametophyte do not have free living existance, they remain wthin sporangia.
*after fertilization zygote develops into an embryo and the ovules into seeds, seeds are not covered.

CYCAS

PINUS

GINKGO

PTERIDOPHYTS

*they are the first  terrestrial plant to posses vascular tissue i.e. xylum and phloem.
*they are soil binder.
*they are used as medicine.
*they are used as ornamental plants.
*they grow in cool, damp and shady places.
*the dominant phase of pteridophyte are sporophyte. in bryophytes it is gametophyte.
*plant body is differentiated into true root, stem and leaf.
*leaf may be microphylls (SELAGINELLA) or macrophylls (FERNS)
*the sporophyte bear sporangia that are subtended by leaf like appendages called sporophylls.
*in some cases sporophylls may form distinct compact structures called strobili or cones.(SELAGINELLA, EQUISETUM)
*sprangia produces spore and spore germinate into prothallus.these gametophyte required cool, damp shady place to grow.
*sexual reproduction by antheridia and archegonium.
*after fertilization zygote produce sporophyte,which is dominant phase.
*the plants which have similar spores are called homosporous.
*the plants which have dissimilar spores are called heterosporous.
*female gamete are larger than male gamete.
*zygote develops into young embryo, it is the precursor to seed habitat.
*pteridophytes are further divided into four classes:-
1.PSILOPSIDA- Psilotum
2.LYCOPSIDA- Selaginella, Lycopodium
3.SPHENOPSIDA- Equisetum4.PTEROPSIDA- Dryopteris,Pteris,Adiantum

SELAGINELLA

LYCOPODIUM

EQUISETUM

DRYOPTERIS

PTERIS

ADIANTUM

PSILOTUM

MOSSES

POLYTRICHUM

SPHAGNUM

FUNARIA

*the predominant phase of mosses is gametophyte, which consists of two stages-the protonema and the leafy stage.
*protonema directly developes from spore it is creeping,green,branched and filamentous stage.
*leafy stage develops from secondary protonema as a lateral bud.
*leafy stage bear sex organ.
*leafy stage have slender axes bearing spirally arranged leaf, attached to soil by multicellular and branched rhizoids.
*vegetative reproduction by fragmentation and budding in secondary protonema.
*sexual reproduction by antheridia and archegonia, after fertilization zygote develops into sporophyte
*sporophyte consists of foot seta and capsule.
*e.g.- Funaria, Polytrichum, Sphagnum

LIVERWORT

*the liverwort grow in moist habitat such as marshy ground,bar of trees etc
*the plant body of liverwort is thalloid.
*asexual reproduction by fragmentation of thalli or by formation of specialised structure called gemmae.
gemmae are green,multicellular, asexual bud which develop in small receptacles called gemma cups located on thalli.
*the gemmae become detached from parent body and germinate to new individual.
*in sexual reproduction male and female organ are produced on same or different thalli.
*the sporophyte are differentiated into foot, septa and capsule.
*after meiosis spore are produced within capsule.these spore germinate to form free living gametophyte.
*e.g.- Marchantia