NCERT Class 11 Biology Chapter 3 Notes Plant Kingdom- Download PDF Notes

CBSE Quick Revision Notes Class 11 Biology Chapter 3: Plant kingdom is a very important biology chapter of the NCERT textbook from the CBSE exam point of view. The NCERT Class 11 Biology Chapter 3 notes give you a basic idea of the plant kingdom and how plants are classified or divided into groups based on their characteristics. The important topics covered in NCERT Class 11 Biology notes are definitions, algae, bryophytes, pteridophytes, gymnosperms, and angiosperms, plant life cycles, alternation of generations; and important examples. Download the CBSE Notes for Class 11 Biology, Chapter 3, PDF to use it offline anywhere. Students must go through each topic in the Plant Kingdom of Class 11 Biology in the easiest and most effective way possible with the help of NCERT Notes for Class 11.

Class 11 biology chapter 3 notes also cover all the important concepts related to this chapter, which are useful in various competitive exams. Plant kingdom NCERT Notes for Class 11 Biology help you revise crucial concepts given in the NCERT Book in no time during the CBSE Board exam preparation. CBSE Class 11 Biology Chapter 3 notes will help you with quick revision. The Plant Kingdom chapter covers all headings of NCERT. CBSE Class 11 Biology chapter 3 notes also contain important examples that have been frequently asked in the various exams. Having NCERT Solutions and revision notes for Class 11 Biology Chapter 3 handy are beneficial to save you time. The NCERT Class 11 notes PDF can be downloaded through the link given below.

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NCERT Class 11 Chapter 3 Class Notes

Plant Kingdom

• Plantae now excludes fungi, as well as members of the Monera and Protista families with cell walls, despite previous classifications placing them in the same kingdom.
• As a result, cyanobacteria, also known as blue-green algae, are no longer considered algae.
• Let us examine classification within angiosperms to gain a better understanding of the concerns that influenced classification systems.
• The earliest classification systems relied solely on gross morphological characteristics such as habit, colour, leaf number and shape, and so on.
• They were mostly based on vegetative characteristics or the structure of the androecium (system given by Linnaeus). such systems were synthetic; they divided closely related species because they were based on a few features.
• Furthermore, the artificial systems accorded equal weight to vegetative and sexual qualities; this is unacceptable because vegetative characters are more easily influenced by the environment.
• Natural classification systems arose in response to this, based on natural affinities among organisms and taking into account not only external but also interior characteristics such as ultrastructure, anatomy, embryology, and phytochemistry.
• George Bentham and Joseph Dalton Hooker were the first to classify blooming plants in this way.
• Phylogenetic classification systems that are based on evolutionary relationships between organisms are currently acceptable.
• This suggests that organisms from the same taxon share a common ancestor.
• We now use data from a variety of other sources to assist us in resolving classification issues.

Algae

• Algae are simple, thalloid, chlorophyll-bearing, autotrophic creatures that are primarily aquatic (both freshwater and marine).
• They can be found in a range of various environments, including damp stones, soils, and wood.
• Some of them are also found in fungi (lichen) and mammals (for example, on sloth bears).
• Algae come in a wide range of shapes and sizes, from colonial forms like Volvox to filamentous forms like Ulothrix and Spirogyra.
• Kelps, for example, are a type of marine organism that forms massive plant bodies.
• Algae reproduce vegetatively, asexually, and sexually.
• Fragmentation is the mode of vegetative reproduction. A thallus forms from each fragment.
• Asexual reproduction occurs through the production of spores of various types, the most common of which are zoospores. They 're being flagellated (motile) and produce new plants after germination.
• The fusing of two gametes results in sexual reproduction.
• These gametes can either be flagellated and of comparable size (as in Ulothrix) or non-flagellated (non-motile) but of comparable size (as in Spirogyra). This type of reproduction is referred to as Isogamous reproduction.
• Anisogamous refers to the fusion of two gametes of different sizes, such as those found in Eudorina species.
• Oogamous fusion occurs when one big, nonmotile (static) female gamete fuses with a smaller, motile male gamete.
• Algae are beneficial to humans in a number of ways.
• Algae photosynthesis accounts for at least half of the total carbon dioxide fixing on the planet.
• They enhance the amount of dissolved oxygen in their immediate environment because they are photosynthetic.
• They are crucial as primary producers of energy-rich chemicals, which are the foundation of all aquatic species' food cycles.
• Chlorophyceae, Phaeophyceae, and Rhodophyceae are the three major groups of algae.

Chlorophyceae

• Green algae are the members of the Chlorophyceae family. Unicellular, colonial, or filamentous plant bodies are all possible.
• Because chlorophyll a and b pigments predominate, they are usually grass green.
• Pigments are concentrated in specific chloroplasts.
• Chloroplasts can be discoid, plate-like, reticulate, cup-shaped, spiral-shaped, or ribbon-shaped in different species; most chloroplast members have one or more pyrenoids as storage bodies.
• Aside from starch, pyrenoids contain protein.
• Vegetative propagation usually occurs by fragmentation or the formation of various types of spores.
• Sexual reproduction can be isogamous, anisogamous, or oogamous, with significant differences in the type and formation of sex cells.
• Chlamydomonas, Volvox, Ulothrix, Spirogyra, and Chara are some of the most common green algae.

Phaeophyceae

• Brown algae, also known as phaeophyceae, are mostly found in marine environments. They come in a wide range of sizes and shapes.
• They range in complexity from basic branched filamentous forms (Ectocarpus) to lavishly branched forms like kelps, which may grow to be 100 meters tall.
• Chlorophyll a, c, carotenoids, and xanthophylls are all present in them.
• Depending on how much of the xanthophyll pigment, fucoxanthin is present in them, they range in colour from olive green to various shades of brown.
• The plant body, which comprises a stalk, the stipe, and a leaf-like photosynthetic organ – the frond – is generally held to the substratum by a holdfast.
• Vegetative reproduction occurs through fragmentation.
• The majority of brown algae reproduce asexually by biflagellate zoospores, which are pear-shaped with two unequally linked flagella.
• Isogamous, anisogamous, or oogamous sexual reproduction is possible.
• Union of gametes can occur in water or within the oogonium (oogamous species).
• The gametes are pyriform (pear-shaped) and have two flagella that are connected laterally.
• Ectocarpus, Dictyota, Laminaria, Sargassum, and Fucus are the most prevalent.

Rhodophyceae

• Rhodophyceae members are usually referred to as red algae due to the preponderance of the red pigment r-phycoerythrin in their bodies.
• The majority of red algae are marine, with higher numbers seen in warmer locations. They can be found in both well-lit areas near the top of the sea and at considerable depths in oceans where relatively little light penetrates.
• The majority of red algae have multicellular red thalli. Some of them have complicated bodily structures.
• The food is kept as floridean starch, which is structurally identical to amylopectin and glycogen.
• Red algae often proliferate vegetatively by fragmentation. They reproduce asexually through non-motile spores and sexually through gametes.
• Sexual reproduction is oogamous, with extensive post-fertilization processes.
• Polysiphonia, Porphyra, Gracilaria, and Gelidium are the most prevalent non-motile members.

Bryophytes

• Bryophytes are mosses and liverworts that are commonly found growing in moist shaded areas of the hills.
• Bryophytes are also recognized as amphibians of the plant kingdom because they can live in soil but require water for sexual reproduction.
• They are most common in damp, humid, and shady environments. They are essential for plant succession on bare rocks/soil.
• Bryophytes have a more differentiated plant body than algae.
• It is thallus-like as well as prostrate or erect, with unicellular or multicellular rhizoids attaching it to the substratum.
• They don't have true roots, stems, or leaves. They can have root, leaf, or stem-like structures.
• The bryophyte's main plant body is haploid. It is called a gametophyte because it produces gametes.
• Bryophytes have multicellular sex organs. Antheridium is referred to as the male sex organ. They synthesize biflagellate antherozoids.
• Archegonium, the flask-shaped female sex organ produces only one egg.
• The antherozoids are discharged into the water, where they interact with archegonium.
• The zygote is formed when an antherozoid combines with an egg. Zygotes do not immediately begin reduction division. They form a multicellular organism known as a sporophyte.
• The sporophyte is not free-living, but is connected to the photosynthetic gametophyte and feeds on it. Some sporophyte cells undergo reduction division (meiosis) to produce haploid spores. These spores germinate, resulting in the formation of gametophytes.
• Bryophytes are not economically important in general, although some mosses supply food for herbaceous mammals, birds, and other animals.
• Because of their ability to hold water, Sphagnum moss species provide peat, which has traditionally been utilized as fuel and as packing material for the trans-shipment of live material.
• Mosses and lichens are the first species to colonize rocks and so have a high ecological value. They decompose rocks, preparing the substrate for higher plant growth.
• Mosses reduce the impact of falling rain and prevent soil erosion by forming dense mats on the soil.
• The bryophytes are classified as liverworts and mosses.

Liverworts

• Liverworts typically grow in moist, shady environments such as stream banks, marshy ground, deep in the woods, damp soil and tree barks.
• A liverwort's plant body is thalloid (e.g., Marchantia) with a dorsiventral thallus that is tightly appressed to the substrate.
• The leafy members feature tiny leaf-like appendages on the stem-like structures in two rows.
• In liverworts, asexual reproduction occurs by thalli fragmentation or the formation of specialized structures known as gemmae.
• Gemmae are green, multicellular, asexual buds that grow in little receptacles on the thalli called gemma cups.
• The gemmae separate from the parent body and germinate, resulting in the formation of new individuals. Male and female sex organs are generated on the same or distinct thalli during sexual reproduction.
• The sporophyte consists of three parts: the foot, the seta, and the capsule.
• Spores are formed within the capsule following meiosis. These spores germinate and develop into free-living gametophytes.

Mosses

• The gametophyte stage, which consists of two stages, is the most important stage of a moss' life cycle.
• The protonema stage is the initial stage, which develops immediately from a spore. It is a creeping stage that is green, branching, and frequently filamentous.
• The second stage is the leafy stage, which grows as a lateral bud from the secondary protonema. They are composed of thin, lean axes with spirally arranged leaves. They are connected to the soil by rhizoids that are multicellular and branching. The sex organs are present at this stage.
• Mosses reproduce vegetatively through fragmentation and blossoming in the secondary protonema.
• The sex organs antheridia and archegonia are generated at the top of the leafy shoots during sexual reproduction.
• The zygote develops into a sporophyte after fertilization, consisting of a foot, seta, and capsule.
• Moss sporophytes are more complex than liverwort sporophytes. Spores are present in the capsule.
• After meiosis, spores develop. Mosses such as Funaria, Polytrichum and Sphagnum are common examples.

Bryophytes: A liverwort – Marchantia

Pteridophytes

• Horsetails and ferns are examples of Pteridophytes. Pteridophytes are useful in medicine and as soil binders. They are also popular as ornamentals.
• They are the first terrestrial plants to have vascular tissues - xylem and phloem.
• Pteridophytes are located in cool, damp, shady areas, yet some can thrive in sandy soil.
• The major plant body of pteridophytes is a sporophyte, which is divided into real roots, stems, and leaves.
• These organs have well-developed vascular tissues. Pteridophyta leaves can be microscopic like Selaginella or huge like ferns.
• Sporophytes have sporangia that are subtended with appendages that are leaf-like and are known as sporophylls.
• Sporophylls can form unique compact structures known as strobili or cones (Selaginella, Equisetum) in certain circumstances.
• Sporangia generate spores by meiosis in spore mother cells.
• The spores germinate and produce prothallus, which are small, free-living, multicellular thalloid gametophytes that are primarily photosynthetic. These gametophytes require cool, wet, shaded conditions to thrive. Because of this very restricted requirement, as well as the necessity of water for fertilization, the expansion of live pteridophytes is limited and geographically confined.
• Male and female sex organs, known as antheridia and archegonia, are found in gametophytes. Male and female sex organs, known as antheridia and archegonia, are found in gametophytes.
• Water is essential for the transmission of antherozoids, or male gametes released by antheridia, to the mouth of archegonium.
• The zygote is formed when a male gamete fuses with an egg in the archegonium.
• After that, the zygote develops into a multicellular, well-differentiated sporophyte, which is the main phase of the pteridophytes.
• The spores in the majority of pteridophytes are all of the same type; such plants are referred to as homosporous.
• Heterosporous refers to genera which include Selaginella and Salvinia, which generate two types of spores, macro (big) and micro (small).
• Psilopsida (Psilotum), Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum) and Pteropsida (Dryopteris, Pteris, Adiantum) are the four classes of pteridophytes.

FERN

Gymnosperms

• Gymnosperms (gymnos = naked, sperma = seeds) are plants in which the ovules are visible both before and after fertilization and are not contained by an ovary wall.
• The seeds that form after fertilization are not coated, i.e., they are naked. Gymnosperms are medium- to tall-sized trees and shrubs.
• Tap roots are the most common type of root. Roots belonging to some genera have fungal associations in the form of mycorrhiza (Pinus), whilst others (Cycas) have small specialized roots termed coralloid roots that are connected with N2 - fixing cyanobacteria.
• The stems are either branched (Pinus, Cedrus) or unbranched (Cycas).
• The leaves can be either simple or complex. Gymnosperm leaves are well-adapted to tolerate temperature, humidity, and wind extremes. The needle-like leaves of conifers decrease surface area. Their thick cuticle and sunken stomata also aid in water conservation.
• Gymnosperms are heterosporous, with haploid microspores and megaspores formed. The two types of spores are formed within sporangia, which are carried on sporophylls that are spirally arranged along an axis to create lax or compact strobili or cones. Microsporangiate, often known as male strobili, are strobili with microsporophylls and microsporangia.
• The microspores mature into a male gametophytic generation that is greatly reduced and confined to a small number of cells. pollen grain is the name given to this reduced gametophyte.
• Pollen grains are formed within the microsporangia. Macrosporangiate or female strobili are cones that contain megasporophylls with ovules or megasporangia.
• Unlike bryophytes and pteridophytes, male and female gametophytes in gymnosperms do not have their own autonomous free-living existence. They persist within the sporangia that have been preserved on the sporophytes.

Pinus, Cycas

Angiosperms

• Unlike gymnosperms, which have bare ovules, angiosperms, or flowering plants, have pollen grains and ovules formed in specialized structures called flowers.
• The seeds of angiosperms are encased in fruits. The angiosperms are a diverse group of plants that live in a variety of environments.
• They range in size from the tiny Wolffia to large Eucalyptus trees (over 100 meters).
• They supply us with food, feed, fuel, medications, and a variety of other commercially vital things.
• They are classified into two groups: dicotyledons and monocotyledons.
• Dicotyledons have two cotyledons in their seeds, reticulate venations in their leaves, and tetramerous or pentamerous flowers, which have four or five members in each floral whorl.
• Monocotyledons, on the other hand, have single cotyledon seeds, leaves with parallel venation, and trimerous flowers with three members in each floral whorl. The stamen is a flower's male sex organ. Each stamen is made up of a thin filament with an anther at the tip.
• The pollen mother cell divides within the anthers via meiosis to produce microspores, which mature into pollen grains. The pistil is a flower's female sex organ. The pistil is made up of a large ovary at the base, a long slender style, and a stigma.
• Ovules can be found inside the ovary. In general, each ovule has a megaspore mother cell that goes through meiosis to produce four haploid megaspores. Three of them degenerate, while one of them divides to produce the embryo sac.
• Each embryo-sac contains a three-celled egg apparatus consisting of one egg cell and two synergids, three antipodal cells, and two polar nuclei. Eventually, the polar nuclei combine to form a diploid secondary nucleus.
• Pollen grain is delivered to the stigma of a pistil by wind or other means after being dispersed from the anthers. This is termed as Pollination.
• Pollen grains germinate on the stigma, and the resultant pollen tubes grow through the stigma and style tissues to reach the ovule. The pollen tubes enter the embryo-sac and release two male gametes.
• A zygote is formed when one of the male gametes unites with an egg cell (syngamy). The triploid primary endosperm nucleus (PEN) is formed when the other male gamete fuses with the diploid secondary nucleus.
• Because of the presence of two fusions, namely syngamy and triple fusion, this phenomenon is known as double fertilization, which is a unique event to angiosperms.
• The zygote grows into an embryo (with one or two cotyledons), and the PEN develops into an endosperm, which feeds the growing embryo.
• After fertilization, the synergids and antipodals degenerate. During these events, the ovules become seeds and the ovaries become fruit.

Plant Life Cycles and Alternation of Generations

• Mitosis allows both haploid and diploid cells in plants to divide. This ability results in the development of haploid and diploid plant bodies.
• Mitosis is the process through which gametes are produced in the haploid plant body. This plant body is a gametophyte.
• The one-celled zygote is the sole representative of sporophytic generation. There are no sporophytes that are free living.
• In the zygote, meiosis results in the generation of haploid spores. The gametophyte is formed when haploid spores divide mitotically.
• The free-living gametophyte is the major photosynthetic phase in such plants. This is referred to as a haplontic life cycle. This pattern is represented by several algae, including Volvox, Spirogyra, and certain Chlamydomonas species.
• On the other end of the spectrum, there is the variety in which the diploid sporophyte is the photosynthetic, dominant and independent phase of the plant.
• The single to few-celled haploid gametophyte represents the gametophytic phase. This is referred to as a diplontic life cycle. alga, Fucus represent this pattern.
• Bryophytes and Pteridophytes have an intermediary stage (Haplo-diplontic); both are multicellular. They do, however, differ in their prominent periods.
• A haploid gametophyte represents a dominant, autonomous, photosynthetic, thalloid, or erect phase that alternates with the short-lived multicellular sporophyte that is fully or partially dependent on the gametophyte for anchoring and feeding. This pattern is shared by all bryophytes.
• A dominating, autonomous, photosynthetic, vascular plant body defines the diploid sporophyte. It alternates with saprophytic/autotrophic, independent, multicellular but short-lived haploid gametophyte.
• This is referred to as the haplo-diplontic life cycle. This pattern is found in all pteridophytes.
• The majority of algal genera are haplontic, although others, including Ectocarpus, Polysiphonia, and kelps, are haplo-diplontic.

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