plant kingdom
Hi student , in these video we start the revision of plant kingdom , we look full biological classification in previes video full boared classification is given by R.H. Whittaker that five kingdom has the phylum monera, protista , fungi, animalia ,plantae. In these chapter we deal with a detail study of kingdom Plantae, in plant kingdom we describe Algae, bryophytes, pteridophytes, gymnosperms, and angiosperms .
Ø At present phylogenetic classification systems belonging to some taxa have a common ancestor .
Ø Now we are starting with Algae .
Ø Algae are chlorophyll-bearing,simple,thalloid, autotrophic, and largest aquatic organisms.
Ø They occur in vaa riety of habitats , some of them are associated with fungi and animals .
Ø The form and size of fungi are highly variable, ranging from colonial forms like volvox and filamentous forms like Ulothrix and Spirogyra and few of marine forms such as kelps .
Ø The algae reproduce by vegetative , asexual, and sexual methods.
Ø In sexual reproduction isogamous reproduction occur means gametes are flagellated and in similar size.
Ø And the fusion of dissimilar in size is called as anisogamous.
Ø Algae are useful to humans in various ways , the half of the total carbon dioxide fixation on earth are carried out by the algae.
Ø They are photosynthetic hence they increase the dissolved oxygen in their immediate
Ø They performs the basics role in the food cycle of aquatic animals .
Ø Their are mainly 70 species of marine algae .
Now we see the type of algae , there are 3 type of algae as follow ,
1. Chlorophyceae
2. Phaeophyceae
3. Rhodophyceae.
We see the 1st type chhlorophyceae in next video ,so take care and be ready for the exams . By
Hi, students welcome to the bio guide we are going to see the revision of plant kingdom. In the previous video we see the revision of algae and their types, in this video we see the full classification of bryophytes.
• Bryophytes include various mosses and liverworts.
• They are commonly found in moist shaded areas in the hills.
• Bryophytes are live in soil but they depend upon water for reproduction hence they also called amphibians of the plant kingdom.
• They play important role in succession on rocks.
• The bryophytes are more differentiated than the algae.
• They possess a root-like , leaf-like, steam-like structure .
• The main plant body of bryophytes is haploid .
• The male sex organ of bryophytes is antheridium, they produce biflagellate antherozoids.
• The female sex organ produces a single egg called archegonium.
• The zygote formed by fusion of archegonium and antheridium does not go to reduction division immediately, they produce a multicellular body called the sporophyte.
• The sporophyte gets the nourishment from photosynthetic gametophyte .
• Some cells of sporophyte are undergo the reduction division,and produce haploid spore.
• Mosses have the gate's economical importance because they are used to colonize rocks.
Here the introduction of bryophyte is over, now let's see their type
i. Liverwort
• they are usually living in moist places,shady habitats ,barks of tree and etc ..
• The plant body of liverworth is thalloid .
• Asexual reproduction in liverwoerth are take place by fragmentation of thalli , or formation of specialised structures called gemmae.
• The gemmae becomes detached form parent body and germinate to form new individuals .
• In sexual reproduction male and female body produce either on the same or different thalli.
• The sporophyte is differentiated into a foot ,seta , and capsule .
• The spore are produce by sporophyte germinate and form free living-gametophytes .
• here the liverworth topic is end and now we start the mosses . But make sure you must take notes in your copy for better revision .
ii. Mosses
• In the predominant stage of moss contain two stages.
A. Protonema
B. Leafy stage
• The smallProtonema stage also called as the filamentous stage , because the gametophyte are directly develops into spore .
• The leafy stage bears the sex organs in it .
• vegetative reproduction occur in mosses by fragmentation and budding in secondary protonema .
• The sex organ antheridia and archegonia at the apex of the leaf shoot .
• After fertilization zygote develops into sporophyte .
• Sporophyte of mosses are more elaborate than that liverwort .
• Some common examples of mosses are - funaria ., sphagnum.
• Here the bryophyte ends and we start the next topic in another video .so tata and by , stay tund ….
Hi, students welcome to Mr. biobuddy youtube channel we are taking the revision of plant kingdom. We see the bryophytes classification in the previous video, click on the I button for it.
Now we start from Pteridophytes.
• Pteridophytes include horsetails and ferns.
• They are also used for medicinal purposes and soil binders.
• They are the first terrestrial plant that contains vascular tissue like xylem and phloem.
• Their organ are well defined like true root, stem, and leaves.
• Their leaves are small as selaginella or large as ferns.
• The sporangia produce spores by meiosis in spore mother cells.
• The spore gives rise to a free-living photosynthetic thalloid gametophyte called prothallus.
• This gametophyte requires a cool, damp, shady place to grow.
• Pteridophytes are grown in specific conditions like needing water for fertilization.
• These gametophyte bears male and female sex organs called antheridia and archegonia.
• water is required for transfer of antheridia.
• The male gamete is released from antheridia to the mouth of the archegonium, their fusion makes zygote
• zygote produces multicellular well-differentiated sporophyte, the dominant pteridophyte phase.
• In the majority of spores are similar kind such plant is called homosporous.
• And that spore produce two or more types are called heterosporous.
• The development of zygotes into the young embryos take place within the female gametophyte, this event is called as seed event consider as important event in evolution.
So here the Pteridophytes end . And here we stop in these video for some technical issue but in next video we finished the chapter full revision . So make sure you subscribe to the channel and like the video and share the video to your friends
Hi students welcome back to the mr biobuddy youtube channel . In the privies video we see the full board classification of Pteridophytes. Click on I button to see it .
In these video we see the full revision of plant kingdom . Now start form
Gymnosperms, Angiosperms and Plant Life Cycles
Gymnosperms
The gymnosperms (Gymnos = naked; sperma = seeds) are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation. These are small groups of seed plants which are represented by only 900 living species. Unlike bryophytes and pteridophytes, in gymnosperms the male and the female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes.
Habitat
These plants are mostly found in colder parts of northern hemisphere, where they form extensive forests. A number of gymnosperms are now, known as ornamentals, e.g., Ginkgo, Thuja, Araucaria, etc.
Morphology
Gymnosperms include, medium-sized trees or tall trees and shrubs. The giant red wood tree Sequoia is one of the forest tree upto 100 m. Species of Gnetum are woody climbers. The smallest gymnosperm is Zamia pygmaea which reaches a height of 25 cm. Many of the gymnosperms live for more than 4000 years, e.g, Pine (Pinus), redwood {Sequoia).
External Features
The plant body is sporophyte and differentiated into root, stem and leaves.
Plant Body
Tap roots are present for proper anchorage to heavy plant. Roots in some genera have fungal association in the form of mycorrhiza {Pinus), while in some others {Cycas) small specialised roots called coralloid roots are associated with N2-fixing cyanobacteria such as Anabaena, Nostoc, etc.
The stems are branched {Pinus, Cedrus) or unbranched {Cycas). The leaves may be simple or compound.
Archegonia
The megaspore mother cell thus, undergo meiotic division forming four megaspores. Out of which one is enclosed within the megasporangium (nucellus) and develops into a multicellular female gametophyte, bearing two or more archegonia of female sex organs.
The multicellular female gametophyte is also retained within megasporangium.
Fertilisation
Air current required for transport of male gametes. The male gametes are carried to the archegonia, i.e., gamete in the ovule by means o’f a tube called pollen tube and discharge their contents near the mouth of the archegonia. This is called siphonogamy
Seeds
Following fertilisation, zygote develops into an embryo and the ovules into seeds. The seeds contain food laden tissue called endosperm. It lies naked or exposed. Endosperm provides nourishment for growth of seedling at the time of seed germination.
Examples Cycas, Pinus, Ginkgo, Ephedra, Gnetum, Vaucheria, Cedrus, Abies, etc.
Classification of Gymnosperms
Gymnospermsfurther include three main classes Cycadopsida (cycads), Coniferopsida (conifers) and Gnetopsida (Gnetum).
Differences between Male Gametophyte of Pteridophyte and Gymnosperms
Male Gametophyte of Pteridophyte Male Gametophyte of Gymnosperms
A distinct male gametophyte may not be present. A distinct male gametophyte is present.
It contains an antheridium. Antheridium is not present.
Male gametes are flagellate. Male gametes can be flagellate or non-flagellate.
Male gametes reach female gametes by swimming in water. Male gamete reach the female gamete through a pollen tube.
Economic Importance of Gymnosperms
(i) Seeds of Pinus gerardiana (chilgoza) are used a food after roasting. Some other edible gymnosperms plant part are endosperm of Ginkgo, seed kernel of some Cycas and Gnetum, sago grains from stems of Cycas, etc.
(ii) Gymnosperms provide softwood for construction, plywood and paper industry.
(iii) Branches of gymnosperm trees are used as fuel food.
Saw dust of conifers is used in making plastics and linoleum.
Resin is a semifluid secreted by special tubes of a number of conifers. It helps in sealing female cones after pollination, scale leaves around leaf bases and apical buds. Resin is distilled to obtain turpentine and resin. Turpentine is used for . thinning paints, varnishes, etc., and resin is used
for sealing joints, wheel green, preparation of writing paper, oil clothes, etc.
Here the gymnosperms ends now start the angiosperms .
Angiosperms
Angiosperms are seed bearing plants or flowering plants. Unlike gymnosperms where the ovules are naked, in angiosperms the sporophyll are organised into flowers and the seeds are produced inside fruits. There are about 250000 species of angiosperms in the nature. They evolved about 130-160 million years ago.
Habitat
Angiosperm are found in wide range of habitats, from the land to up to 6000 m in Himalayas or Antarctica and Tundra, dry hot deserts, cold deserts, tropics, fresh water up to 60°C, underground, over other plants as parasites, saprophyte, etc. Zostera is a marine angiosperm.
Plant Body
These plant are sporophytic, in the form of herbs, shrubs, trees, climber creepers, etc. The smallest angiosperm is water plant Wolffia and tallest is Eucalyptus regnans (100 mand above). Primary root develops from radicle. It forms tap root system. In many angiosperms roots develop from places other than radicle, these are adventitious roots. Stem develops from plumule.
Leaves
These are simple or compound. The leaves bear axillary buds which can grow into stem branches.
Vascular Tissues
Angiosperms have vessels in xylem. Phloem contains sieve tubes and companion cells in regard to gymnosperms which do not have companion cells.
Flowers
Flowers are the reproductive structures formed by the union of one or both types of sporophylls (microsporophylls or stamens and megasporophylls or carpels).
Microsporophylls or Male Sex Organs
Stamens are considered as the male sex organs of a flower. Each stamen has two main parts, i.e., a slender filament with an anther (at the tip). An anther contains four microsporangia where microspore mother cells become differentiated to form four microspores, each developing into a pollen grain.
Megasporophylls or Female Sex Organs
Carpel or pistil is called the female sex organ of the flower. Each carpel has three parts {i.e., an ovary, style and stigma). A megaspore mother cell is differentiated in the nucellus and undergoes meiosis, ultimately one functional megaspore gets enlarged and forms the female gametophyte known as embryo-sac.
Each cell of an embryo sac is haploid:
Embryo Sac
Each embryosac contains a three celled eg® apparatus consisting I of one egg cell and two synergids, three antipodal cells (at the i opposite end) and two polar nuclei (in the central cell). The polar : nuclei eventually fuses and forms diploid secondary nucleus.
Pollination
Pollen grains after dispersal from the anthers are carried by various ways such as wind, water or by various other agencies to the stigma of the pistil.
Fertilisation and Development of a Seed
Each pollen grain germinates on the stigma forming a pollen tube that carries two male gametes to the embryo sac, growing through the tissues of stigma and style.
One of the male gametes fuses with the egg cell to form a zygote (syngamy).
The other male gamete fuses with the diploid secondary nucleus to produce the triploid Primary Endosperm Nucleus (PEN). Because of the involvement of above mentioned two events, it is known as double fertilisation. After fertilisation, synergids and antipodal cells degenerate.
The zygote develops into embryo and the primary endosperm nucleus develops into an endosperm.
The ovule gradually transforms into a seed and the ovary becomes the fruit. A fruit is actually a ripened ovary. They not only protect the seed but also help in their dispersal.
Classification of Angiosperms
George Bentham and Joseph Dalton Hooker presented the system of classification of angiosperm* published in Genera Plantarum (1862-1883) which appeared in three volumes.
This system of classification is used by most of the well known Herbaria of the world. The details of this system are not described here. Conveniently, on the basis of the number of cotyledons angiosperm are classified in two broad groups i.e., Monocotyledonae and Dicotyledonae.
Economic Importance of Angiosperms
(i) The angiosperms are major source of food, fibers, spices and beverages.
(ii) They also provide valuable timber and medicines.
(iii) These also add beauty to our environment as well.
Alteration of Generation
Life cycle of an organism is a sequence of events that occur from birth to death of an organism. In plants, both haploid and diploid cells can divide by mitosis.
This feature leads to the formation of different plant bodies haploid and diploid. The haploid plant body produces gametes by mitosis. This plant body represents a gametophyte.
After fertilization, zygote also divides by mitosis to produce a diploid saprophytic plant body. Haploid spores are produced by this plant body by meiosis. These in turn, divide by mitosis to form a haploid plant body once again.
Thus, during the life cycle of any sexually reproducing plant, there is an alternation of generation between gamete producing haploid gametophyte and spore producing diploid saprophyte.
Plant Life Cycles
Different plant groups and individual have different features in their life cycle
Haplontic
The dominant photosynthetic phase is a gametophyte produced by haploid spores. The gametophyte produces gametes by mitosis.
The gametes fuse and produce a diploid zygote, that represents sporophytic generation. There are no free living sporophytes. Meiosis in the zygote results in formation of haploid spores. This kind of life cycle is called haplontic.
Many algae such as Volvox, Spirogyra and Chlamydomonas represent this pattern of life cycle.
Diplontic
In this type, the diploid sporophyte is the dominant. The multicellular diploid phase is called sporophyte. The gametophytic phase is represented by the single to few celled haploid gametophyte.
This kind of life cycle is termed as diplontic. All seed bearing plants, gymnosperms and angiosperms follow this pattern of life cycle. Fucus, an alga is diplontic.
Haplodiplontic
In this type, there are two distinct multicellular phases, diploid sporophyte and haploid gametophyte are present. Both phases are multicellular. However, they dilfer in their dominant phases.
(i) A dominant, independent, photosynthetic, thalloid or erect phase is represented by a haploid gametophyte. It alternates with the short lived multicellular sporophyte totally, partially or dependent on the gametophyte for its anchorage and nutrition. All bryophytes represent this pattern.
(ii) The diploid saprophyte is represented by a dominant independent photosynthetic vascular plant body. It alternates with multicellular saprophytic/autotrophic,
independent but short lived haploid gametophyte. This pattern is called haplodiplontic life cycle.
All pteridophytes demonstrate this pattern. However, most algal genera are haplontic, some of them such as Ectocarpus, Polysiphonia and kelps are haplodiplontic.
Here we end the full revision of plant kingdom . We also going to see the revision of animals kingdom so please subscribe to our channel and make sure you like the video .
Ads go here
Aditya .....I love u bro
ReplyDelete