class 11 biology Plant kingdom ppt

class 11 chapter 4 Plant Kingdom ppt

1. Types of Biological classifications There are three types of biological classifications. They are:- Artificial System Natural System Phylogenetic System

2. Artificial System of Classification Earliest system of classification. Based on vegetative characters or superficial morphological characters like habit, number, colour, shape of leaves, etc. Linnaeus artificial system of classification was based on the androecium structure .

3. Drawbacks:- Separated closely reated species. Equal weightage of vegetative and sexual characteristics.

4. Natural System of Classification Based on natural affinities among organisms. Considers external and internal features. Classification given by George Benthem & Joseph Dalton Hooker.

5. Phylogenitic System of Classification Based on evolutionary relationship among the organisms. Assumes that organisms in the same taxa have a common ancestor.

6. Simple. Thalloid. Autotropic. Chlorophyll bearing. Aquatic(fresh water and marine)organisms. Some occur in association with fungi called lichen. Some occur in association with animals .(sloth bear) Form and size are variable. Vegetative reproduction by fragmentation. Asexual reproduction by production of spores (zoospores). Sexual reproduction by fusion of gamates.

7. ( Isogamous, Anisogamous, oogamous). Fix half of the total CO 2 on the earth, through photosynthesis. Increase the level of dissolved oxygen. Primary producers and the basis of the food cycles of all aquatic animals. Marine algae(about 70%) used as food. Agar is used to grow microbes and in ice-creams and jellies. Some marine red and brown algae produce carrageen and hydrocolloids. Protein rich unicellular algae are used as food supplements by space travellers.

8. It is divided into three. Chlorophyceae(green algae), Phaeophyceae(brown algae), Rhodophyceae(red algae).

9. Unicellular. Colonial. Filamentous. Green colour due to the pigment chlorophyll a & b in chloroplasts. Chloroplasts may be discoid, plate like, reticulate, cup shaped, spiral and ribbon shaped. Most of them have one or more pyrenoids in chloroplast. Some algae store food as oil droplets. Have rigid cell wall made of an inner cellulose layer and an outer pectose layer.

10. Examples:- Chlamydomonas ; Volvox ; Ulothrix ; Spirogyra ; Chara.

11. Phaeophyceae

12. Mostly marine. Show great variation in size and form. Pigments present are chlorophyll a,c, carotenoids and xanthophylls. Vary colour from olive green to brown depending on the amount of xanthophyll pigment and fucoxanthin. Food stored as complex carbohydrates(laminarin or manitol) Vegetative cells have a cellulosic wall covered by a gelatinous coating of algin.

13. Protoplast contains plastids, central vacuole and nucleus. Body attached to a substratum by a holdfast and has a stalk(stipe) and leaf like photosynthetic organ is found. Vegetative reproduction by fragmentation. Asexual reproduction by pear shaped biflagellate zoospores. Sexual reproduction by isogamous, anisogamous and oogamous. Examples:- ectocarpus, dictyota, laminaria, sargassum and fucus.

14. Red Algae

15. Have red thalli due to the red pigment r-phycoerythrin. Mostly marine and also occur in regions close to the surface of water and at great depths in oceans. Mostly multicellular. Have complex body organisation. Food stored as floridean starch. Vegetative reproduction by fragmentation. Asexual rproduction by non-motile spores. Sexual reproduction by oogamous. Examples:- polysiphonia, porphyra, gracilaria

16. BRYOPHYTES

17. Called as Amphibians of the plant kingdom. They can live in soil, but need water for sexual reproduction. Occur in damp, humid, and shaded localities. Body is thallus-like and prostrate or erect attached to the substratum by unicellular or multicellular rhizoids. Lack true roots, leaves and stem. May possess root-like, leaf-like or stem-like structures. Main plant body is haploid. Produce gametes therefore, called as gametophytes.

18. Sex organs are multicellular. Male sex organ is antheridium which produce antherozoids. Female sex organ is archegonium which produce single egg. Antherozoids are released to water and meets archegonium. Antherozoids fuses with the egg to form zygote. Zygote produce multicellular body called sporophyte. Sporophyte is not free living.

19. Sporophyte derives nourishment from the photosynthetic gametophyte. Some mosses provide food for herbaceous mammals,birds, etc. Species of Sphagnum(a moss) provide peat. Used as fuel. Has water holding capacity so that can be used as packing trans-shipment of living materials. Mosses along with lichens decompose rocks making the substrate suitable for the growth of higher plants.

20. Substrate can prevent soil-erosion. Are divided into two:- (i) Liverworts (ii) Mosses

21. Moist and shady habitat. Body is thalloid. Thallus is dorso-ventral and closely appressed to the substrate. Leafy members have tiny leaf-like appendages in two rows on the stem like structure. Asexual reproduction by fragmentation and gemme formation. Gemme are green, multi-cellular, asexual buds that develop in smal receptacles on the thalli.

22. Gemme are detached from the parent body and germinate to form new individuals. Sexual reproduction - male and female sex organs are produced on the same or different thalli. Sporophyte is differentiated into foot, seta and capsule. After meiosis, spores are produced within the capsule. These spores germinate to form free-living gametophyte.

23. Predominant stage is called gametophyte. Consist of two stages protonema and leafy stage. Vegetative reproduction by fragmentation and budding. Antheridia and archegonia are produced at the apex of leafy shoots. After fertilisation, zygote develops to a sporophyte having foot, seta and capsule. Sporophyte is elaborate than in liverworts. Capsule contains spores, formed after meiosis. Mosses have an elaborate mechanism of spore dispersal.

24. Examples:- Funaria, Sphagnum, Polytrichum.

25. PTERIDOPHYTES

26. Include horsetails and ferns. Found in cool, damp and shady areas. Flourish well in sandy-soil. First terrestrial plants to possess vascular tissues i.e., xylem and phloem. Dominant phase is sporophyte. Differentiated into true roots, stem and leaves. Leaves are small or large. Used for medicinal purposes. Used as soil binders.

27. Grown as ornamentals. Bear sporangia that are subtended by leaf like appendages called sporophylls. Sporophyll form distinct compact structures called strobili or cones. Sporangia produce spores by meiosis in mother cells. Spores germinate to give inconspicuous, small, multicellular, free living, mostly photosynthetic, thalloid gametophyte called prothallus. Thalloid requires cool, damp, shady places to grow,

28. Need water for fertilization. Gametophytes bear male and female sex organ antheridia and archegonia. Water is needed for the transfer of antherozoids to the mouth of archegonium. Antherozoid fuses with the egg in the archegonium to form zygote. Zygote develops to a multicellular well differentiated sporophyte. Most pteridophytes produce similar kinds of spores(homo-

29. sporous plants). Others produce two kinds of spores macro(mega) & microspores and are called as heterosporous. The spores germinate and give rise to female and male gametophytes. Within female gametophyte, zygote develop into young embryos . This event is a precursor to the seed habit and is considered as an important step in evolution. Is divided into four. They are :

30. (i) Psilopsida (ii) Lycopsida (iii) Sphenopsida (iv) Pteropsida Examples:- Selanginella and Salvinia

31. GYMNOSPERMS

32. Ovules are not enclosed by ovary wall. Seeds that develop post-fertilization are not covered. Include medium sized trees or tall trees or shrubs. Sequoia (giant redwood)is the tallest tree species. Roots are generally tap roots. Roots in some have fungal association in the form of mycorrhiza. Roots in some have small specialised roots with Nitrogen fixing cyanobacteria. Stems are branched or unbranched.

33. Leaves are simple or compound. Leaves are well-adapted to withstand extreme temperature, humidity and wind. Pinnate leaves persist for a few years. The needle like leaves reduce the surface area. The sunken stomata and the thick cuticle of the needle like leaves help to reduce water loss. Heterosporous- produce haploid microspores and megaspores. Some leaves are modified into sporophylls.

34. Sporophylls bear sporangia in which spores are produced. Sporophylls are of two types. They are : (i) microsporophylls (ii) megasporophylls Male and female cones may be born on the same or different trees. Male and female gametophytes do not have an independent free-living existence. Pollen grains released from th e microsporangium are

35. carried by air currents and meet the opening the ovules. After fertilization, zygote develops into an embryo and the ovules into seeds. (i) Microsporophylls:- Arranged to male strobili. Bear microsporangia. Microspores develop into male gametophyte called pollen grains. Pollen grains are developed within the microsporangia.

36. (ii) Megasporophylls:- Arranged to female strobili. Bear megasporangia. Mainly consist of a body called nucellus, protected by envelops. Megaspore mother cell is differentiated from a cell of the nucellus. Mother cell undergoes meiosis to form four megaspores.

37. ANGIOSPERMS

38. Large group of plants. Range from microscopic to tall trees. Divided into two. They are dicotyledon and monocotyledon. Dicotyledon:- Have two cotyledon in seeds. Have reticulate venation in leaves. Tetramerous or pentamerous flowers ( 4 or 5 members in each floral whorl). Have tap roots.

39. II Monocotyledon:- Have one cotyledon in seed. Parallel venatation in leaves. Trimerous flowers (3 members in each floral whorl). Fibrous roots. Reproductive structure is flower. Male sex organ is stamen.

40. Stamen consist of filament with an anther at the tip. The pollen mother cell divides by meiosis to produce microspores which matures into pollen grains. Female sex organ is pistil. Pistil consist of ovary at its base, a long slender style and stigma. Ovary contains ovules. Ovule has a megaspore mother cell that undergoes meiosis to form four haploid megaspores. Three of them degenerate and one divides to form embryo sac.

41. Each embryo sac has a three celled egg apparatus(one egg cell and two synergids), three antipodal cells and two polar nuclei. Polar nuclei fuse to produce a secondary nucleus(2n). Pollen grains are dispersed from the anthers and carried by wind or other agencies to the stigma of a pistil and the process is called pollination. Pollen grains germinate on the stigma and the resulting pollen tubes grow through the tissues of stigma and style and reach the ovule.

42. Pollen tubes enter the embryo sac where two male gametes are discharged.One male gamete fuses with egg cell to form zygote(syngamy). Other male fuses with diploid secondary nucleus to produce triploid primary endosperm nucleus (PEN) because of the involvement of two fusions, this event is called double fertilization and is an event unique to angiosperms. Zygote develops into an embryo. PEN develops into endosperm which provides nourishment

43. to the developing embryo. Synergids and antipodals degenerate after fertilization. Ovules develop into seeds and ovaries develop into fruits. Seeds are enclosed by fruits.

44. PLANT LIFE CYCLES AND ALTERNATION OF GENERATIONS

45. In plants, both haploid and diploid cells can divide by mitosis. This forms haploid and diploid plant bodies. Haploid plant body (gametophyte) produces gamates by mitosis. After fertilization, the zygote also divides by mitosis to produce diploid plant body(sporophyte). This produces haploid spores by meiosis.Spores divide by mitosis to form a haploid plant body. Thus, during the life cycle of any sexually reproducing plants,there is an alternation of generation between gametophyte and sporophyte.

46. Haplontic In this, sporophytic generation is represented only by the zygote. Zygote undergoes meiosis to form haploid spores. They divide mitotically to form gametophyte. The dominant, photosynthetic phase is the free-living gametophyte. Examples:- Algae such as Volvox, Spirogyra, and some species of Chlamydomonas.

47. Haplontic

48. Diplontic In this, the diploid sporophyte is the dominant, photosynthetic, independent phase. Gametophytic phase is represented by the single to few celled haploid gametophyte. Examples:- Algae, Fucus, all seed bearing plants (gymnosperms and angiosperms - the gametophytic phase is few to multi-celled).

49. Diplontic

50. Haplo-Diplontic It is the intermediate condition between haplontic and diplontic. Both gametophyte and sporophyte are multicellular and often free living. But they have different dominant phases. Examples:- Bryophytes and Pteridophytes.

51. Haplo-Diplontic