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Plant Kingdom · Class 11 NEET Notes

Complete Class 11 notes on Plant Kingdom, told as one story: how plants left the water. Nine diagrams, a comparison table that answers most questions, trap alerts and a fact sheet. Free to read or download.

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1Comparison table
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In short

The Plant Kingdom reads as a single story: how plants left the water. Algae are still tied to it, bryophytes need it to reproduce, pteridophytes gain vascular tissue, gymnosperms free the seed from water entirely, and angiosperms add the flower and double fertilisation. Each step trades dependence on water for something new.

Contents
  1. ·Read This First
  2. 1How Plants Are Classified and what the syllabus now expects
  3. 2Algae three classes, told by pigment
  4. 3Life Cycles haplontic, diplontic, and the middle case
  5. 4Bryophytes the amphibians of the plant world
  6. 5Pteridophytes the first plants with plumbing
  7. 6Gymnosperms seeds, but left uncovered
  8. 7Angiosperms the seed gets a cover
  9. ★Plant Kingdom · Fact Sheet
0

Read This First

  • This chapter is worth about 3 percent of NEET, based on the last ten years of papers.
  • It is almost pure recall. So the marks go to whoever revises the comparisons, not to whoever reads the most.
  • Throughout these notes, blue marks a defining feature and red marks a trap or a first appearance.
  • The single most useful page is the comparison table in Section 6. Learn that and most questions fall.
Trap alert
A note on the rationalised NCERT
  • NCERT trimmed some content from this chapter in the rationalised edition.
  • These notes are built on the core that every edition keeps: the five groups, their features, and the life cycles.
  • If your school follows an older book, check the classification section at the front against your current edition.
  • When in doubt, the current NCERT is the syllabus. Nothing else is.
1

How Plants Are Classified

  • Early systems used only a few easy characters, such as habit. These are called artificial systems.
  • Natural systems use many characters together, including internal structure.
  • Phylogenetic systems group plants by how closely they are related by descent.
  • Three modern aids: numerical taxonomy gives each character a number and lets a computer weigh them, cytotaxonomy uses chromosome data, and chemotaxonomy uses chemical constituents.
The five groups in the order they appear. Each step solves one more problem of living on land.FIVE GROUPS, ONE DIRECTION OF TRAVELALGAEBRYOPHYTESPTERIDOPHYTESGYMNOSPERMSANGIOSPERMSno vascular tissueno vascular tissuefirst vascular plantsfirst seeds, nakedseeds inside fruitwater needed for fertilisationYES, alwaysNO, pollen carries the male gamete
The five groups in the order they appear. Each step solves one more problem of living on land.
Think it through
The one story that ties the chapter together
  • Plants began in water, where sperm could simply swim to the egg.
  • Moving onto land created two problems: support and water for fertilisation.
  • Vascular tissue solved support, and it arrives with the pteridophytes.
  • Pollen solved the water problem, and it arrives with the gymnosperms.
  • Read every group as an answer to one of those two problems.
2

Algae

  • Simple, mostly aquatic plants. The body is a thallus, with no true root, stem or leaf.
  • Reproduction can be vegetative (fragmentation), asexual (spores) or sexual.
  • Sexual reproduction runs from isogamous (both gametes alike) to anisogamous (different sizes) to oogamous (large still egg, small motile sperm).
  • Economic value: about half of all photosynthesis on Earth, plus agar, algin and carrageenan.
The three classes side by side. Pigment sets the colour, and the stored food is the fact most often asked.THE THREE ALGAL CLASSES: PIGMENT DECIDES THE COLOURCHLOROPHYCEAE (green)pigmentchlorophyll a, bstored foodstarchcell wallcelluloseflagella2 to 8, equalChlamydomonas, Volvox, UlothrixPHAEOPHYCEAE (brown)pigmentchl a, c + fucoxanthinstored foodmannitol, laminarincell wallcellulose + alginflagella2, unequal, lateralLaminaria, Fucus, SargassumRHODOPHYCEAE (red)pigmentchl a, d + r-phycoerythrinstored foodfloridean starchcell wallcellulose + pectinflagellaABSENTPolysiphonia, Gelidium
The three classes side by side. Pigment sets the colour, and the stored food is the fact most often asked.
Trap alert
The four facts examiners ask from this table
  • Red algae have NO flagella at any stage. That single fact appears again and again.
  • Stored food: green stores starch, brown stores mannitol and laminarin, red stores floridean starch.
  • Fucoxanthin makes brown algae brown. r-phycoerythrin makes red algae red.
  • Brown algae have two unequal flagella, attached at the side, not at the tip.
Algae all blurring together?
Sort them by pigment and watch the colours separate.

The classification game deals you an alga and asks for its class, pigment and food store. Three rounds and the table sticks.

Play this concept in the app
3

Life Cycles

  • Every plant alternates between two bodies: a haploid gametophyte and a diploid sporophyte.
  • Fertilisation joins two gametes and doubles the number, giving 2n.
  • Meiosis makes spores and halves it again, giving n.
  • Which of the two bodies dominates is what separates the groups.
The whole cycle in one picture. Fertilisation doubles, meiosis halves, and it repeats.ALTERNATION OF GENERATIONS: THE ENGINE OF EVERY PLANT LIFE CYCLEGAMETOPHYTEhaploid (n)SPOROPHYTEdiploid (2n)gametes fuse: FERTILISATIONn + n gives 2nspores form: MEIOSIS2n gives nFertilisation doubles the number. Meiosis halves it. The cycle simply repeats.
The whole cycle in one picture. Fertilisation doubles, meiosis halves, and it repeats.
Three patterns. Moving right, the diploid sporophyte takes over more of the life cycle.THREE LIFE CYCLES. BLUE IS HAPLOID (n), RED IS DIPLOID (2n)HAPLONTICzygote is the only 2n stagegametophytedominantVolvox, Spirogyra, ChlamydomonasHAPLO-DIPLONTICboth phases are multicellularbothdominantbryophytes and pteridophytesDIPLONTICgametes are the only n stagesporophytedominantseed plants, and FucusMoving right, the diploid sporophyte takes over more and more of the life cycle.
Three patterns. Moving right, the diploid sporophyte takes over more of the life cycle.
Think it through
How to answer any life cycle question
  • Ask one thing: which body is the bigger, longer-lived one?
  • If the gametophyte wins, it is haplontic (algae) or haplo-diplontic (bryophytes).
  • If the sporophyte wins, it is haplo-diplontic (pteridophytes) or diplontic (seed plants).
  • Fucus is the exception: a brown alga with a diplontic cycle, like a seed plant.
4

Bryophytes

  • Mosses and liverworts. They live on land but still depend on water, which is why they are called the amphibians of the plant world.
  • The plant body is the gametophyte. It has no true roots, stems or leaves.
  • No vascular tissue at all, so they stay small and grow in damp, shady places.
  • The sporophyte is smaller, and it stays attached to the gametophyte and draws food from it.
A liverwort spreads flat. A moss stands upright. In both, the green plant you see is the gametophyte.BRYOPHYTES: THE AMPHIBIANS OF THE PLANT WORLDLIVERWORT (Marchantia)flat, ribbon-like thallusrhizoids anchor itMOSS (Funaria)capsule (2n)leafy gametophyte (n)upright, with tiny leaf-like structuresThe GAMETOPHYTE is the main plant. The sporophyte is smaller and stays attached to it,drawing nourishment from it. Water is still needed to carry the sperm to the egg.No true roots, stems or leaves, and no vascular tissue.
A liverwort spreads flat. A moss stands upright. In both, the green plant you see is the gametophyte.
  • Liverworts reproduce asexually by gemmae, held in cup-shaped gemma cups.
  • The moss sporophyte has three parts: foot, seta and capsule.
  • Ecological value: they are the first to colonise bare rock, and they slow soil erosion.
  • Sphagnum (peat moss) is used as packing material for sending live plant material.
5

Pteridophytes

  • Ferns and their relatives. These are the first plants with vascular tissue, so xylem and phloem appear here.
  • They have true roots, stems and leaves, which bryophytes never had.
  • The sporophyte is now the main plant. This is the big switch in the chapter.
  • The gametophyte is a small, free-living, heart-shaped prothallus.
The fern you recognise is the sporophyte. The gametophyte is the tiny separate prothallus.PTERIDOPHYTES: THE FIRST PLANTS WITH PLUMBINGfrond (leaf)sori: clusters of sporangiaon the underside of the frondprothallus: the tiny free-livingheart-shaped gametophyte (n)WHAT IS NEW HEREtrue roots, stem and leavesxylem and phloem appearsporophyte is now DOMINANTgametophyte is small and freestill needs water for spermspores, but no seeds yet
The fern you recognise is the sporophyte. The gametophyte is the tiny separate prothallus.
  • Spores are made in sporangia, which are grouped into sori under the leaf.
  • Homosporous means one kind of spore. Heterosporous means two kinds, large and small.
  • Selaginella and Salvinia are heterosporous, and that is the fact most often asked.
  • Heterospory is important because it is the first step towards the seed habit.
Trap alert
Water is still the limit
  • Pteridophytes solved support, but not reproduction.
  • The sperm still has to swim to the egg, so a film of water is essential.
  • This is why ferns still grow in cool, damp, shady places despite having plumbing.
  • The next group solves exactly this problem.
6

Gymnosperms

  • The first seed plants. The seed is the big idea: a young plant packed with food inside a coat.
  • Gymno means naked and sperma means seed. The seeds sit exposed on the cone scales, with no fruit wall around them.
  • There is no ovary, so there can be no true fruit.
  • Pollen is carried by wind, so no water is needed for fertilisation. This finally frees plants from damp places.
Male cones make pollen. Female cones carry the naked seeds. Wind does the rest.GYMNOSPERMS: SEEDS, BUT LEFT UNCOVEREDa conifer, such as Pinusmale conetiny, makes pollenfemale coneseeds sit naked on the scalesKEY POINTSnaked seeds, no fruit wallno ovary, so no true fruitpollen is carried by WINDno water needed for fertilisationxylem has no vesselsphloem has no companion cellsmostly needle leaves, thick cuticle
Male cones make pollen. Female cones carry the naked seeds. Wind does the rest.
  • Usually tall trees with a thick, woody stem. Leaves are often needle-like with a thick cuticle, which cuts water loss.
  • Xylem has no vessels and phloem has no companion cells. This is a favourite one-mark question.
  • They are heterosporous: microspores give pollen, megaspores stay in the ovule.
  • Examples: Pinus, Cycas, Ginkgo, and Cedrus.
One table for the whole chapter. Red marks where a feature first appears, which is where questions cluster.ONE TABLE THAT ANSWERS MOST PLANT KINGDOM QUESTIONSFEATUREALGAEBRYOPHYTESPTERIDOPHYTESGYMNOSPERMSVascular tissueabsentabsentPRESENTpresentDominant phasegametophytegametophytesporophytesporophyteTrue rootsabsentabsentpresentpresentWater for fertilisingyesyesyesNOSeedsabsentabsentabsentPRESENT, nakedLife cyclehaplontichaplo-diplontichaplo-diplonticdiplonticRed marks the first appearance of a feature. That is where the questions cluster.
One table for the whole chapter. Red marks where a feature first appears, which is where questions cluster.
7

Angiosperms

  • The flowering plants. The seed is now enclosed inside a fruit, which is what the name means.
  • The flower is the reproductive structure. The ovary ripens into the fruit.
  • They are split into dicots (two cotyledons, net-veined leaves, tap root) and monocots (one cotyledon, parallel veins, fibrous root).
  • They range from the tiny Wolffia to the giant Eucalyptus.
Two fusions happen, not one. That is double fertilisation, and it is unique to this group.ANGIOSPERMS: THE SEED GETS A COVER, AND FERTILISATION HAPPENS TWICEovary wall becomes the FRUITovulestigmapollen grainpollen tube grows downMALE GAMETE 1 + EGGgives the ZYGOTE (2n)this grows into the embryoMALE GAMETE 2 + TWO POLAR NUCLEIgives the ENDOSPERM (3n)this feeds the growing embryoDouble fertilisation happens in angiosperms only. Nowhere else in the plant kingdom.
Two fusions happen, not one. That is double fertilisation, and it is unique to this group.
Trap alert
Double fertilisation, and the numbers that go with it
  • One male gamete fuses with the egg to give the zygote, 2n, which becomes the embryo.
  • The other fuses with two polar nuclei to give the endosperm, 3n, which feeds the embryo.
  • 3n is the number to remember. Answering 2n for the endosperm is the standard slip.
  • This double event happens in angiosperms only, nowhere else in the plant kingdom.

★ Plant Kingdom · Fact Sheet

Every formula for revision day. Print this page alone.

ALGAE, GREEN

Chlorophyll a and b

Starch. Cellulose wall.
Chlamydomonas, Volvox, Ulothrix.

ALGAE, BROWN

Fucoxanthin gives the colour

Mannitol and laminarin.
2 unequal lateral flagella.

ALGAE, RED

r-phycoerythrin

Floridean starch.
NO flagella at any stage.

LIFE CYCLES

Haplontic: algae

Haplo-diplontic: bryo, pterido
Diplontic: seed plants, Fucus.

BRYOPHYTES

Gametophyte dominant

No vascular tissue, no true roots
Sporophyte attached to it.

BRYOPHYTE PARTS

Sporophyte: foot, seta, capsule

Gemmae in gemma cups
Sphagnum gives peat.

PTERIDOPHYTES

First VASCULAR plants

Sporophyte dominant
Prothallus is the gametophyte.

HETEROSPORY

Two spore sizes

Selaginella and Salvinia
First step to the seed.

GYMNOSPERMS

Naked seeds, no ovary, no fruit

Wind pollinated, no water needed
Pinus, Cycas, Ginkgo, Cedrus.

GYMNOSPERM TISSUE

Xylem has NO vessels

Phloem has NO companion cells
Needle leaves, thick cuticle.

ANGIOSPERMS

Seed enclosed in a fruit

Dicot: 2 cotyledons, net veins
Monocot: 1, parallel veins.

DOUBLE FERTILISATION

Gamete + egg = zygote (2n)

Gamete + 2 polar nuclei = 3n
Angiosperms ONLY.

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