Plant Kingdom

The Plant Kingdom (Kingdom Plantae) includes all eukaryotic, multicellular,

autotrophic organisms that synthesize food through photosynthesis.
This kingdom plays a critical role in maintaining life on Earth through oxygen
production, carbon dioxide absorption, and forming the base of most food chains.

Basis of Classification in Plant Kingdom

Classification helps in organizing knowledge, predicting characteristics, and
understanding evolutionary relationships among organisms. In plants, classification is
based on several key criteria.

1. Presence or Absence of Vascular Tissues (Conducting Systems)

●​ Non-vascular plants: Lack specialized tissues for conduction (xylem & phloem).​
Example: Bryophytes
●​ Vascular plants: Possess vascular tissues for transport of water and nutrients.​
Example: Pteridophytes, Gymnosperms, Angiosperms

2. Differentiation of Body into Root, Stem, and Leaves

●​ Thalloid body: Undifferentiated plant body (thallus).​
Seen in Algae, Liverworts
●​ Differentiated body: Shows distinct root, stem, and leaves.​
Seen in Pteridophytes, Gymnosperms, Angiosperms

3. Habitat
●​ Aquatic: Live in freshwater/marine environments.​
Example: Algae like Spirogyra
●​ Terrestrial: Adapted to land habitats.​
Example: Bryophytes, Pteridophytes

4. Presence or Absence of Seeds

●​ Seedless plants: Produce spores instead of seeds.​
Example: Bryophytes, Pteridophytes
●​ Seed-bearing plants: Produce seeds through sexual reproduction.​
Example: Gymnosperms, Angiosperms

5. Type of Seeds
●​ Naked seeds: Not enclosed in fruits.​
Example: Gymnosperms (e.g., Pinus)
●​ Enclosed seeds: Protected within fruits.​
Example: Angiosperms (e.g., Mango, Apple)

6. Type of Gametophyte and Sporophyte Dominance

●​ In lower plants like algae and bryophytes, gametophyte (haploid) is dominant.
●​ In higher plants like pteridophytes and beyond, sporophyte (diploid) is dominant.
 Summary Table: Basis of Plant Classification
Higher Plants
Lower Plants
(e.g.,
Feature (e.g., Algae,
Gymnosperms,
Bryophytes)
Angiosperms)

Vascular
Absent Present
tissue

Plant body Thalloid or

Well differentiated
differentiation simple

Seed
No Yes
production

Type of
Spore-based Seed-based
reproduction

Dominant Gametophyte
Sporophyte
generation (mostly)

Major Groups of Plant Kingdom (as per NCERT)

Plant Kingdom is classified into:
Algae – Simple, aquatic, photosynthetic plants
Bryophytes – First land plants; non-vascular
Pteridophytes – Vascular seedless plants
Gymnosperms – Vascular seed plants with naked seeds
Angiosperms – Vascular seed plants with enclosed seeds (flowering plants)

Importance of Alternation of Generations

One of the most fundamental concepts in plant biology is the phenomenon
of Alternation of Generations, a reproductive cycle that alternates between two
distinct multicellular stages:
1. Sporophyte (Diploid) – 2n
●​ Develops from the zygote after fertilization.
●​ Produces haploid spores via meiosis.
●​ Dominant stage in vascular plants like ferns, gymnosperms, and angiosperms.
2. Gametophyte (Haploid) – n
●​ Arises from spores.
●​ Produces gametes (egg and sperm) via mitosis.
●​ Dominant stage in non-vascular plants like bryophytes.

Life Cycle: Alternation Process

1.​ Gametes (n) fuse → Zygote (2n)
2.​ Zygote develops into Sporophyte (2n)
3.​ Sporophyte undergoes meiosis → Spores (n)
 4.​ Spores grow into Gametophyte (n)
5.​ Gametophyte produces Gametes (n)

Alternation of Generations = Gametophyte ↔ Sporophyte

Types of Life Cycles Based on Dominance

1. Haplontic Life Cycle (Gametophyte Dominant)

●​ Sporophyte is short-lived and dependent on gametophyte.
●​ Common in Algae like Chlamydomonas, Spirogyra.

2. Diplontic Life Cycle (Sporophyte Dominant)

●​ Gametophyte is highly reduced (few cells).
●​ Typical in Gymnosperms and Angiosperms.
●​ Example: Mango, Pinus

3. Haplo-Diplontic Life Cycle (Both Generations Equal or Prominent)

●​ Both gametophyte and sporophyte are multicellular and independent.
●​ Found in Bryophytes and Pteridophytes.
Type of Dominant
Example
Life Cycle Phase

Gametophyte Spirogyra,
Haplontic
(n) Chlamydomonas

Sporophyte
Diplontic Mango, Pinus
(2n)

Haplo-diplo Both
Ferns, Mosses
ntic prominent

Key Concepts and NCERT Highlights

NCERT Example-based Points

●​ Algae (e.g., Volvox, Ulothrix) – show haplontic life cycle
●​ Bryophytes (e.g., Marchantia, Funaria) – haplo-diplontic life cycle with gametophyte
dominance
●​ Pteridophytes (e.g., Ferns) – haplo-diplontic with sporophyte dominance
●​ Gymnosperms and Angiosperms – diplontic life cycle; sporophyte is the main plant
body
 Summary of Key Points
Topic Key Details

Multicellular, eukaryotic,
Kingdom
autotrophic organisms
Plantae
with cellulose cell walls.

Vascular tissues, body

Basis of structure, reproduction,
Classification seed type, dominance
stage.

Algae, Bryophytes,
Pteridophytes,
Major Groups
Gymnosperms,
Angiosperms.

Reproductive cycle
Alternation of alternating between
Generations gametophyte and
sporophyte.

Life Cycle Haplontic, Diplontic,

Types Haplo-diplontic.

Chlamydomonas
(haplontic), Funaria
NCERT
(bryophyte), Fern
Examples
(pteridophyte), Mango
(angiosperm).

Frequently asked in
NEET MCQs based on
Importance examples, dominance,
and life cycles.

NEET Focused Questions (Practice)

1.​ Which plant group lacks vascular tissues?​
A. Pteridophytes​
B. Angiosperms​
C. Gymnosperms​
D. Bryophytes
 2.​ In which life cycle is the gametophyte the dominant generation?​
A. Diplontic​
B. Haplontic​
C. Haplo-diplontic​
D. None
3.​ Match the following:
●​ Spirogyra → (i) Haplontic
●​ Marchantia → (ii) Haplo-diplontic
●​ Pinus → (iii) Diplontic
Correct Match: Spirogyra – (i), Marchantia – (ii), Pinus – (iii)

Algae

Introduction
Algae are simple, chlorophyll-bearing, autotrophic organisms that perform
photosynthesis like higher plants.
They are mostly aquatic and form the base of many aquatic food chains. Despite
their simplicity, they are incredibly diverse in structure, reproduction, and life
cycles.
Algae contribute significantly to global oxygen production, form the foundation of
aquatic ecosystems, and are used in commercial products.

General Characteristics of Algae

1.​ Autotrophic: Perform photosynthesis using chlorophyll.
2.​ Simple Thallus Body: No true roots, stems, or leaves.
3.​ Eukaryotic: All algae studied in the NCERT belong to the domain Eukarya.
4.​ Unicellular or Multicellular: Forms range from unicellular (Chlamydomonas) to
multicellular filamentous (Spirogyra) or colonial (Volvox).
5.​ Aquatic: Mostly found in fresh or marine water. Some grow in moist soil or on tree
bark (epiphytic).
6.​ Cell Wall: Composed of cellulose and other complex polysaccharides.
7.​ Pigmentation: Possess different types of chlorophyll and accessory pigments,
depending on the class (green, brown, red).

Habitat & Thallus Organization

Habitat
Aquatic:
Freshwater (e.g., Spirogyra)
Marine (e.g., Sargassum)
Terrestrial:
Moist soil, bark, or rocks
Others:
Epiphytes (grow on other plants)
Endosymbionts (live inside other organisms)
Thallus Organization
Unicellular Motile: e.g., Chlamydomonas
Unicellular Non-motile: e.g., Chlorella
Colonial: e.g., Volvox (many cells together forming a colony)
Filamentous:
Unbranched: e.g., Spirogyra
Branched: e.g., Cladophora
Parenchymatous: Multicellular complex forms (e.g., Laminaria)

Reproduction in Algae
Algae show all three types of reproduction:
vegetative, asexual, and sexual.
Vegetative Reproduction
Definition: Simple cell division or fragmentation of thallus into daughter individuals.
Example: Fragmentation in Spirogyra, Chlamydomonas divides mitotically.
Asexual Reproduction
Occurs through: Formation of spores
Zoospores: Flagellated, motile spores (e.g., Chlamydomonas)
Aplanospores: Non-motile spores
Common in: Algae under favorable conditions
Sexual Reproduction
Involves fusion of male and female gametes
Types of gametic fusion:
Isogamy: Gametes similar in size and shape​
Example: Spirogyra, Ulothrix
Anisogamy: Gametes differ in size​
Example: Chlamydomonas (some species)
Oogamy: Large non-motile egg and small motile sperm​
Example: Volvox, Fucus

Life Cycle Patterns in Algae

Algae exhibit the haplontic life cycle, and rarely diplontic or haplo-diplontic.
1. Haplontic Life Cycle
●​ Dominant phase: Gametophyte (n)
●​ Zygote: The only diploid stage, undergoes meiosis immediately
●​ Example: Chlamydomonas, Spirogyra
2. Diplontic Life Cycle
●​ Dominant phase: Sporophyte (2n)
●​ Gametes formed via meiosis
●​ Example: Fucus (a brown alga)
3. Haplo-diplontic Life Cycle
●​ Both haploid gametophyte and diploid sporophyte are multicellular
●​ Example: Ectocarpus (brown algae)

Types of Algae (NCERT Classification)

Algae are divided into three major classes based on type of pigments, food
storage materials, and cell wall composition:

1. Chlorophyceae (Green Algae)

Characteristics
●​ Pigments: Chlorophyll a and b (gives green color)
●​ Stored food: Starch
●​ Cell wall: Cellulose and pectose
●​ Flagella: 2-8, equal in length (apical insertion)
●​ Thallus: Unicellular, colonial, or filamentous
Reproduction
●​ All three types: vegetative, asexual (zoospores), sexual (isogamy/oogamy)
NCERT Examples
●​ Chlamydomonas – Unicellular, motile
●​ Volvox – Colonial, motile
●​ Ulothrix and Spirogyra – Filamentous
●​ Chlorella – Unicellular, non-motile, used in space food

2. Phaeophyceae (Brown Algae)

Characteristics
●​ Pigments: Chlorophyll a, c, and fucoxanthin (brown color)
●​ Stored food: Mannitol and laminarin
●​ Cell wall: Cellulose with algin (gel-like)
●​ Flagella: Two unequal, lateral
●​ Thallus: Branched, filamentous or flat leaf-like; commonly marine
Reproduction
●​ Vegetative (fragmentation)
●​ Asexual (zoospores with two unequal flagella)
●​ Sexual (isogamy, anisogamy, oogamy)
NCERT Examples
●​ Ectocarpus – Branched filamentous
●​ Dictyota – Leaf-like flat thallus
●​ Laminaria, Fucus, Sargassum – Large and complex marine forms

3. Rhodophyceae (Red Algae)

Characteristics
●​ Pigments: Chlorophyll a and d, phycoerythrin (red pigment)
●​ Stored food: Floridean starch
●​ Cell wall: Cellulose, pectin, and polysulphate esters
●​ Flagella: Absent
●​ Habitat: Mostly marine, prefer deep waters due to efficiency in absorbing blue light
Reproduction
●​ Vegetative (fragmentation)
●​ Asexual (non-motile spores)
●​ Sexual (oogamous, no flagellated gametes)
NCERT Examples
●​ Polysiphonia – Highly branched
●​ Porphyra – Edible seaweed
●​ Gracilaria, Gelidium – Used in agar-agar preparation

Comparison Table of Algae Classes

Chlorophyceae
Feature Phaeophyceae (Brown) Rhodophyceae (Red)
(Green)

Chlorophyll a, c + Chlorophyll a, d +
Main Pigments Chlorophyll a, b
fucoxanthin phycoerythrin

Stored Food Starch Mannitol, Laminarin Floridean starch

Cellulose + Pectin +
Cell Wall Cellulose + Pectose Cellulose + Algin
Esters

Habitat Freshwater/Marine Mostly Marine Mostly Marine (deep)

Flagella Equal, apical Two, unequal, lateral Absent

Sexual
Isogamy to oogamy Iso/Aniso/Oogamy Oogamy only
Reproduction

Examples Ulothrix, Spirogyra Laminaria, Fucus Polysiphonia, Gelidium

 NEET Key Points Summary
Key Concept Highlight

Photosynthetic, thalloid,
Algae
aquatic, unicellular to
Characteristics
multicellular

Vegetative Fragmentation, cell

Reproduction division

Asexual Via zoospores or

Reproduction aplanospores

Sexual Isogamy, Anisogamy,

Reproduction Oogamy

Haplontic mostly, some

Life Cycle
diplontic/haplo-diplontic

Green algae, store starch,

Chlorophyceae
e.g., Spirogyra, Volvox

Brown algae, marine,

Phaeophyceae fucoxanthin pigment, e.g.,
Fucus, Laminaria

Red algae, marine, deep

Rhodophyceae sea, no flagella, e.g.,
Polysiphonia, Gelidium

Real-world Importance of Algae

●​ Oxygen production: ~50% of Earth’s O₂ comes from algae
●​ Aquatic food chains: Base of the pyramid
●​ Commercial use:
Agar (from Gelidium)
Carrageenan (from red algae, used in food industry)
Alginates (from brown algae, used in textiles, cosmetics)
●​ Biofertilizers: Blue-green algae fix atmospheric nitrogen
●​ Biofuels and space food: Chlorella and Spirulina are rich in proteins
 NCERT-Aligned Examples & Questions for NEET Practice
1.​ Which pigment is responsible for the brown color in Phaeophyceae?​
A. Fucoxanthin
2.​ Identify a unicellular non-motile green alga used in space food:​
B. Chlorella
3.​ Rhodophyceae store their food in the form of:​
C. Floridean starch
4.​ Which of the following has no flagella at any stage?​
D. Polysiphonia (Rhodophyceae)
5.​ Match the following:
●​ Spirogyra → (i) Fragmentation
●​ Chlamydomonas → (ii) Zoospores
●​ Fucus → (iii) Diplontic cycle​
Correct match: i – Fragmentation, ii – Zoospores, iii – Diplontic

Bryophytes
Bryophytes are the first land plants and are known as the amphibians of
the plant kingdom because they need water for sexual reproduction.
They form a critical evolutionary link between algae and vascular plants.
Bryophytes are non-vascular, meaning they lack xylem and phloem tissues.
Despite their simple body structure, they play important roles in ecosystems.

General Characteristics of Bryophytes

1.​ Non-vascular Plants
No true vascular tissue (xylem and phloem)
No roots, stems, or leaves (instead, they have rhizoids)
2.​ Gametophyte Dominant Life Cycle
The main plant body is haploid (n), called gametophyte
Diploid sporophyte is dependent on the gametophyte for nutrition
3.​ Amphibians of the Plant Kingdom
Require water for reproduction (flagellated sperm swims to egg)
4.​ Habitat
Moist, shady environments like damp soils, tree trunks, and rocks
5.​ Thalloid or Leafy Body
Body is either flattened (thalloid) or has leaf-like structures
6.​ No Flowers or Seeds
Reproduce via spores formed in capsules (part of the sporophyte)
7.​ Alternation of Generations
Show clear alternation between gametophyte and sporophyte stages

Structure of Bryophytes: Thalloid and Leafy Forms

1. Thalloid Structure
●​ Seen in Liverworts
●​ Plant body is flat, dorsiventrally differentiated (upper and lower surfaces)
●​ Rhizoids present for attachment (unicellular or multicellular)
●​ No vascular tissue or true roots
Example: Marchantia
2. Leafy Structure
●​ Seen in Mosses
●​ Plant body appears like small stem with tiny leaf-like appendages
●​ Rhizoids are multicellular and branched
●​ Better internal organization than thalloid forms
Example: Funaria

Reproduction in Bryophytes
Bryophytes reproduce by vegetative, asexual, and sexual methods.
1. Vegetative Reproduction
●​ Fragmentation: Plant body breaks into fragments and each grows into a new plant​
Seen in Riccia, Marchantia
●​ Gemmae: Special structures for asexual reproduction, common in liverworts​
Found in gemma cups in Marchantia

2. Sexual Reproduction
●​ Oogamous: Male gamete (antherozoid) is small, motile; female gamete (egg) is
large, non-motile
●​ Sex organs:
●​ Antheridia: Male organ producing antherozoids (flagellated)
●​ Archegonia: Female organ producing eggs (flask-shaped)
●​ Fertilization:
●​ Occurs only in the presence of water
●​ Antherozoids swim to the archegonia and fertilize the egg
●​ Zygote → Develops into sporophyte (diploid)

3. Sporophyte
●​ Diploid structure attached to the gametophyte**
●​ Cannot survive independently; remains attached to gametophyte for nutrition
●​ Divided into:
 ●​ Foot: Anchors sporophyte to gametophyte
●​ Seta: Stalk-like portion
●​ Capsule: Contains spores (haploid) formed by meiosis

Alternation of Generations
●​ Gametophyte (n) – Dominant, independent, photosynthetic
●​ Sporophyte (2n) – Attached, dependent, non-photosynthetic (or partially
photosynthetic)
●​ Spores (haploid) germinate to form new gametophytes

Ecological Importance of Bryophytes

1.​ Soil Formation
●​ Bryophytes like mosses grow on rocks, help in weathering and soil formation
2.​ Soil Conservation
●​ Form dense mats that bind soil and prevent erosion
3.​ Water Retention
●​ Act like sponges and retain water in forests, aiding plant growth
4.​ Pioneer Species in Succession
●​ First to colonize barren rocks in ecological succession
5.​ Indicator Species
●​ Sensitive to pollution and used as bioindicators
6.​ Peat Formation
●​ Some mosses (e.g., Sphagnum) form peat used as fuel and soil conditioner

Classification of Bryophytes
Bryophytes are classified into two main groups for NEET based on NCERT:
1. Liverworts (Class: Hepaticopsida)
General Features
●​ Thalloid gametophyte: Flat and dorsiventral
●​ Rhizoids are unicellular
●​ Gemmae present for vegetative propagation
●​ Antheridia and archegonia are produced on special branches (in some)
Reproduction
●​ Sexual reproduction is oogamous
●​ After fertilization: zygote → sporophyte → spores via meiosis
NCERT Examples
●​ Marchantia: Thalloid body, gemmae present
●​ Riccia: Simplest liverwort
2. Mosses (Class: Bryopsida)
General Features
●​ Plant body shows two stages:
1.​ Protonema stage – Creeping, green, branched, filamentous (juvenile stage)
2.​ Leafy stage – Upright, with stem-like axis and leaf-like structures
●​ Rhizoids: Multicellular and branched
Reproduction
●​ Sex organs produced on leafy shoot
●​ Fertilization leads to formation of sporophyte with:
●​ Foot, seta, capsule
●​ Capsule releases spores which form protonema, continuing life cycle
NCERT Examples
●​ Funaria: Common moss, leafy gametophyte
●​ Polytrichum: Tall moss, distinct leafy structure
●​ Sphagnum: Forms peat, helps in water retention

Comparison: Liverworts vs. Mosses

Feature Liverworts Mosses

Gametophyte Thalloid (flat Leafy (stem-like

Form body) axis with leaves)

Multicellular,
Rhizoids Unicellular
branched

Vegetative Gemmae (in

Fragmentation
Repro. gemma cups)

Protonema
Juvenile Stage Not distinct
(filamentous)

Simple, Elaborate, long

Sporophyte
short-lived seta and capsule

Funaria,
NCERT Marchantia,
Polytrichum,
Examples Riccia
Sphagnum
 NEET Key Points
Concept Highlight

Gametophyte (haploid,
Plant Body
dominant)

Vascular Tissue Absent

Antheridia (male),
Sex Organs
Archegonia (female)

Water Essential for fertilization

Requirement (motile sperm)

Diploid, dependent on
Sporophyte
gametophyte

Heteromorphic:
Alternation of
gametophyte (n) dominant,
Generations
sporophyte (2n) short-lived

Vegetative Gemmae (liverworts),

Reproduction fragmentation (mosses)

Important Marchantia, Riccia, Funaria,

Bryophytes Sphagnum, Polytrichum

Soil formation, water

Ecological Role retention, bioindicators,
succession

Frequently Asked NEET MCQs on Bryophytes

1.​ Which group is known as the amphibians of the plant kingdom?​
Bryophytes
2.​ The main plant body in bryophytes is:​
Gametophyte
3.​ Which of the following has a protonema stage?​
Funaria
4.​ Gemmae are used for vegetative reproduction in:​
Marchantia
5.​ The sporophyte in bryophytes is:​
Dependent on the gametophyte
 Pteridophytes
Introduction to Pteridophytes
Pteridophytes are the first vascular plants in the plant kingdom and occupy an
important evolutionary position as they are the first terrestrial plants with true
roots, stems, and leaves, along with vascular tissues (xylem and phloem).
They are seedless and reproduce via spores, not seeds or flowers.
NCERT Definition: “The Pteridophytes include horse tails and ferns. These are the
first terrestrial plants to possess vascular tissues – xylem and phloem.”

General Features of Pteridophytes

1.​ Terrestrial, Seedless Vascular Plants
●​ Thrive in moist, shady places
●​ Some species survive in dry areas
2.​ Dominant Sporophyte Generation
●​ Unlike bryophytes, where the gametophyte is dominant, pteridophytes
have a dominant diploid sporophyte which is independent and
photosynthetic
3.​ True Roots, Stems, and Leaves
●​ Roots: True roots, usually adventitious
●​ Stems: Can be underground (rhizome) or aerial
●​ Leaves:
●​ Microphylls: Small, single-veined (e.g., Selaginella)
●​ Macrophylls (Fronds): Large, with complex venation (e.g., ferns)
4.​ Vascular Tissue Present
●​ Xylem (mostly tracheids) and phloem (no companion cells)
●​ Efficient water and nutrient transport → allows larger body size
5.​ No Flowers or Seeds
●​ Reproduce via spores; absence of seeds makes them cryptogams
6.​ Photosynthetic Sporophyte
●​ The green sporophyte is self-sufficient (independent)
7.​ Cuticle and Stomata Present
●​ Adaptation to reduce water loss

Sporophyte: The Dominant Plant Body

●​ Diploid (2n) and forms the main plant body
●​ Differentiated into:
 ●​ Roots: Penetrate the soil and absorb water/nutrients
●​ Stem: May be aerial or underground (e.g., rhizome in ferns)
●​ Leaves:
●​ Small or large
●​ Often spirally arranged and compound (especially in ferns)
●​ Sporangia develop on special leaves called sporophylls
●​ In some cases, sporophylls form compact structures called strobili or cones (e.g.,
Selaginella, Equisetum)

Reproduction in Pteridophytes

Asexual Reproduction
●​ By spores produced inside sporangia
●​ Sporangia are borne on the undersides of leaves (as in ferns) or in cones

Types of Spores
1.​ Homosporous Pteridophytes
●​ Produce one type of spore (e.g., Lycopodium, Equisetum, Pteris)
●​ All spores are similar and give rise to bisexual gametophytes
2.​ Heterosporous Pteridophytes
●​ Produce two types of spores:
●​ Microspores → Male gametophyte
●​ Megaspores → Female gametophyte
●​ Examples: Selaginella, Salvinia
●​ Considered evolutionary link to seed habit

Gametophyte: Prothallus
●​ Formed from spore germination
●​ Small, multicellular, free-living, usually photosynthetic
●​ Haploid (n) and independent, unlike bryophytes where gametophyte is dominant

Characteristics of Prothallus:
●​ Develops sex organs:
●​ Antheridia: Male sex organs, produce flagellated antherozoids
●​ Archegonia: Female sex organs, flask-shaped, produce eggs
●​ Water is essential for fertilization:
●​ Male gametes swim to archegonium and fertilize the egg
●​ Fertilization → Zygote → Embryo → New Sporophyte
 Alternation of Generations in Pteridophytes
●​ Sporophyte (2n) → Meiosis → Spores (n) →
●​ Spores → Germinate → Gametophyte (Prothallus) (n) →
●​ Produces gametes → Fertilization → Zygote (2n) →
●​ New Sporophyte
Distinct Alternation of Generations
●​ Dominant phase = Sporophyte
●​ Short-lived = Gametophyte (Prothallus)

Homosporous vs. Heterosporous Pteridophytes

Feature Homosporous Heterosporous

Two types
Spore Type One type (microspore &
megaspore)

Gametophyte Bisexual (antheridia Unisexual (male or

Type + archegonia) female)

Pteris, Lycopodium,
Examples Selaginella, Salvinia
Equisetum

Yes (precursor to
Seed Link No
seed habit)

Ecological and Evolutionary Importance

1.​ Soil Binders
●​ Roots hold the soil, preventing erosion
2.​ Pioneers in Succession
●​ Colonize rocks → help in soil formation
3.​ Evolutionary Link
●​ Transition between non-vascular (bryophytes) and seed plants
(gymnosperms)
4.​ Medicinal Uses
●​ Some species (e.g., Equisetum) used in herbal medicine
5.​ Horticultural Value
●​ Ferns are popular ornamental plants
 NCERT Examples of Pteridophytes

Ferns (e.g., Pteris, Dryopteris, Adiantum)

●​ Macrophylls with leaflets
●​ Sporangia borne on underside of leaves
●​ Prothallus forms after spore germination

Horsetails (e.g., Equisetum)

●​ Jointed stems with nodes and internodes
●​ Leaves reduced to small scales
●​ Sporangia in cone-like structures (strobili)

Club Mosses (e.g., Lycopodium, Selaginella)

●​ Lycopodium: Homosporous, cones bear sporophylls
●​ Selaginella: Heterosporous, evolutionarily significant

Structure of a Typical Fern Leaf (Frond)

●​ Frond = Macrophyll, compound leaf
●​ Rachis = Central axis
●​ Pinnae = Leaflets
●​ Sori = Clusters of sporangia on lower surface
●​ Indusium = Protective covering over sori

NEET-Level Key Points

Concept Highlights

Pteridophytes (xylem &

First Vascular Plants
phloem present)

Dominant Sporophyte (2n),

Generation independent

Reproduction Via spores (not seeds)

Prothallus – free-living,
Gametophyte
short-lived

Water needed; motile

Fertilization
male gametes
 Concept Highlights

Homosporous vs Important for NEET

Heterosporous (seed evolution link)

Important Ferns (Pteris), Horsetails

Examples (Equisetum), Selaginella

Top NEET MCQs (Frequently Asked)

1.​ The dominant phase in pteridophytes is:​
Sporophyte
2.​ Heterospory is found in:​
Selaginella
3.​ The gametophyte of pteridophytes is called:​
Prothallus
4.​ Fertilization in pteridophytes requires:​
Water
5.​ Sporangia in ferns are present on:​
Underside of leaves

Gymnosperms
Introduction to Gymnosperms
Gymnosperms (Greek: Gymnos = naked, sperma = seed) are seed-producing
plants whose seeds are not enclosed within fruits. These are non-flowering
plants that bear naked seeds directly on the surface of scales or cones.
Gymnosperms represent a major group of vascular plants and form an
evolutionary link between pteridophytes and angiosperms.
NCERT Definition: “The gymnosperms are the plants in which the ovules are not
enclosed by any ovary wall and remain exposed before and after fertilization.”

General Characteristics of Gymnosperms

1.​ Naked Seeds:
●​ Seeds are exposed, not enclosed within a fruit (no ovary wall)
●​ Develop on the surface of cone scales
2.​ Vascular Plants:
●​ Well-developed xylem and phloem
 ●​ Xylem lacks vessels (except in Gnetum)
3.​ True Roots, Stems, and Leaves:
●​ Roots: Taproot system (with coralloid roots in Cycas)
●​ Stems: May be branched (e.g., Pinus) or unbranched (e.g., Cycas)
●​ Leaves:
●​ Can be simple or compound
●​ Often needle-like (e.g., Pinus) to reduce water loss
●​ Covered with thick cuticle and sunken stomata (xerophytic
adaptation)
4.​ Woody Plants:
●​ Mostly perennial trees or shrubs
●​ Secondary growth common, leading to thick woody trunks
5.​ Cones or Strobili:
●​ Reproductive organs are in cones (strobili)
●​ Separate male and female cones
6.​ No Flowers or Fruits:
●​ Absence of true flowers
●​ No formation of fruits due to absence of ovary

Reproduction in Gymnosperms
Gymnosperms are heterosporous, producing two types of spores:
●​ Microspores (Male) → Male gametophyte (pollen grain)
●​ Megaspores (Female) → Female gametophyte (ovule)
These spores develop in specialized structures within male and female cones.

Male Cones (Microsporangiate Cones)

●​ Bear microsporophylls with microsporangia
●​ Microspores (pollen grains) formed by meiosis
●​ Male cones are smaller and produce pollen grains

Female Cones (Megasporangiate Cones)

●​ Bear megasporophylls with ovules
●​ Megaspores formed within nucellus of ovule
●​ Develop into female gametophytes

Pollination
●​ Mode: Anemophilous (pollination by wind)
●​ Pollen grains are light and dry; dispersed by wind
●​ No need for water for fertilization (unlike bryophytes/pteridophytes)
 Fertilization and Seed Formation
●​ Male gametes reach the ovule via pollen tube
●​ Fusion of male and female gametes → Zygote
●​ Develops into embryo
●​ Ovule → Seed (exposed on cone scale)

Key Point: Gymnosperms do not exhibit double fertilization or formation

of endosperm through triple fusion.

Life Cycle of Gymnosperms

Alternation of generations is heteromorphic with a
dominant sporophyte generation:
1.​ Sporophyte (2n): Main tree/body
2.​ Produces spores via meiosis (microspores and megaspores)
3.​ Spores → Male and Female gametophytes
4.​ Gametophytes → Gametes
5.​ Fertilization → Zygote → Embryo → New Sporophyte
Life cycle is diplohaplontic with dominant diploid sporophyte and reduced,
dependent haploid gametophyte

Alternation of Generations
Phase Type Description

Dominant,
Diploid
Sporophyte photosynthetic,
(2n)
independent

Reduced,
Haploid
Gametophyte non-photosynthetic,
(n)
dependent

Habitat and Adaptations

1.​ Xerophytes (dry habitats):
●​ Needle-like leaves, thick cuticle
●​ Sunken stomata for reduced transpiration
2.​ Coralloid Roots (in Cycas):
 ●​ Have cyanobacteria (Nostoc, Anabaena) for nitrogen fixation
3.​ Mycorrhizal Associations (e.g., Pinus):
●​ Roots associated with fungi to enhance mineral absorption

Structure of Gymnosperm Ovule

●​ Integumented, Megasporangium (nucellus)
●​ Retains megaspore inside the nucellus (no shedding)
●​ One megaspore → Female gametophyte → Archegonia
Unlike angiosperms, gymnosperm ovules are exposed before and after
fertilization.

Economic Importance of Gymnosperms

Use Example

Timber/Wood Pinus, Cedrus

Paper Industry Pulp from Conifers

Resin Production Pine resin → Turpentine

Ornamental
Cycas, Ginkgo
Plants

Edible seeds (e.g., pine

Food
nuts)

Ephedra (source of
Medicinal Uses
ephedrine)

NCERT Gymnosperm Examples

Cycas
●​ Unbranched stem
●​ Coralloid roots (nitrogen-fixing cyanobacteria)
●​ Dioecious (male and female plants separate)
●​ Archegonia visible (as in lower plants)
●​ Motile spermatozoids (spiral flagella)

Pinus (Pine)
●​ Branched tree with needle-like leaves
 ●​ Mycorrhizal roots
●​ Monoecious (both male and female cones on same plant)
●​ Pollen grains winged for wind pollination

Ginkgo (Ginkgo biloba)

●​ Living fossil (primitive traits)
●​ Fan-shaped leaves
●​ Dioecious tree with motile sperm

Key Differences: Gymnosperms vs Angiosperms

Feature Gymnosperms Angiosperms

Enclosed seeds
Seed Type Naked seeds
(in fruit)

Flowers Absent Present

Double
Absent Present
Fertilization

Enclosed within
Ovules Exposed
ovary

Endosperm Before fertilization After fertilization

Formation (haploid) (triploid)

Important NEET Points & Facts

Concept Detail

Gymnosperm
Not enclosed in fruit
Seeds

Male Pollen grain (develops in

Gametophyte microspore)

Female Develops from megaspore

Gametophyte within ovule

Mostly wind
Pollination Type
(anemophilous)
 Concept Detail

Double
Absent
Fertilization

Examples in Cycas, Pinus, Ginkgo,

NEET Ephedra

Pollen tube in
Fertilization
Pinus/Ginkgo; motile
Type
sperms in Cycas

Diagram Suggestion
Prompt:​
“Draw and label the life cycle of a gymnosperm including male cone, female cone,
ovule, pollen grain, gametophyte formation, fertilization, and seed formation
stages. Include Pinus tree.”
●​ Alt Text: Life cycle of a gymnosperm (Pinus) with male and female cones
●​ Title: Gymnosperm Life Cycle – Pinus Reproduction
●​ Caption: Alternation of generations in gymnosperms
●​ SEO Tags: gymnosperm diagram, pinus life cycle, gymnosperm reproduction NEET

Summary Table for Revision

Feature Description

Dominant
Diploid Sporophyte
Generation

Highly reduced,
Gametophyte
dependent, haploid

Naked seeds (not enclosed

Seed Enclosure
in ovary)

Pollination Mostly wind-pollinated

Single fertilization; no
Fertilization
endosperm by triple fusion

Timber, paper, medicine,

Economic Use
edible seeds
 Feature Description

Important Cycas, Pinus, Ginkgo,

Examples Gnetum, Ephedra

NEET Practice MCQs (With Answers)

1.​ Gymnosperms are characterized by:​
Naked seeds
●​ Which of the following has motile sperms?​
Cycas
2.​ Gametophyte in gymnosperms is:​
Multicellular, dependent on sporophyte
3.​ Pollination in gymnosperms is mostly:​
By wind
4.​ Double fertilization is found in:​
Gymnosperms​
Angiosperms (Correct)

Angiosperms
Introduction to Angiosperms
Angiosperms (Greek: Angio = enclosed, sperma = seed) are the most advanced
and dominant group of plants on Earth. They are commonly known as flowering
plants and are characterized by seeds enclosed within fruits (developed from
ovary).
NCERT Definition: “Angiosperms are plants that bear flowers and form seeds
enclosed within fruits.”
These plants show the highest level of organization, adaptation, and diversity,
making them crucial for human survival and the ecosystem.

General Characteristics of Angiosperms

1.​ Presence of Flowers:
●​ Specialized reproductive structures
●​ Consist of sepals, petals, stamens (male), and carpels (female)
2.​ Seed Enclosed in Fruit:
●​ Seeds are enclosed in ovaries
●​ Ovary matures into fruit after fertilization
3.​ Double Fertilization:
 ●​ A unique feature of angiosperms
●​ One sperm fertilizes egg (zygote), another fuses with two polar nuclei to
form triploid endosperm
4.​ Well-Developed Vascular Tissues:
●​ Xylem has vessels and tracheids
●​ Phloem has sieve tubes and companion cells
5.​ Broad Habitat Distribution:
●​ Found in aquatic, terrestrial, desert, and cold environments
●​ Range from tiny herbs to large trees
6.​ Variety of Leaves, Stems, and Roots:
●​ Roots: Taproot or fibrous
●​ Stems: Herbaceous or woody
●​ Leaves: Broad, with various shapes, margins, and arrangements

Structure of the Flower (Reproductive Unit)

Floral Part Description

Green, protect flower in bud

Sepals (Calyx)
stage

Petals Often colorful, attract

(Corolla) pollinators

Stamens Male part (anther + filament)

Female part (ovary, style,

Carpels
stigma)
●​ Flowers may be bisexual (both sexes) or unisexual

Reproduction in Angiosperms
Angiosperms reproduce sexually through flowers. The reproductive process
includes:
1.​ Pollination
2.​ Fertilization (Double)
3.​ Seed and Fruit Formation

Pollination
●​ Transfer of pollen from anther to stigma
●​ Types: Self-pollination and Cross-pollination
●​ Agents: Wind, water, insects, birds, bats
 Fertilization (Double Fertilization)

Unique to angiosperms
●​ One male gamete + egg cell → Zygote (2n)
●​ One male gamete + two polar nuclei → Endosperm (3n)
●​ Results in embryo and nutritive endosperm tissue

Endosperm Formation
●​ Provides nutrition to developing embryo
●​ Formed before or after embryo in different species
●​ Can be:
●​ Nuclear (e.g., maize)
●​ Cellular (e.g., petunia)
●​ Helobial (intermediate type)

Life Cycle of Angiosperms

Angiosperms exhibit alternation of generations – a cycle between a diploid
sporophyte and a haploid gametophyte.
Generation Description

Sporophyte Dominant, forms flowers,

(2n) undergoes meiosis

Gametophyte Pollen grain (male), embryo

(n) sac (female)

Life Cycle Process:

1.​ Flowering Plant (Sporophyte) produces microspores (pollen) and megaspores
2.​ Microspore → Pollen Grain → Male Gametophyte
3.​ Megaspore → Embryo Sac → Female Gametophyte
4.​ Pollination → Double Fertilization
5.​ Zygote (2n) → Embryo → New plant (sporophyte)

Classification of Angiosperms
Angiosperms are divided into two main plant groups:
1. Monocotyledons (Monocots)
Feature Description

Seed Leaves
One
(Cotyledons)

Leaf Venation Parallel

Vascular Bundles Scattered

Root Type Fibrous

Floral Parts In multiples of 3

Secondary Growth Usually absent

Grass, Rice, Maize,

Examples
Banana

2. Dicotyledons (Dicots)
Feature Description

Seed Leaves
Two
(Cotyledons)

Leaf Venation Reticulate (net-like)

Vascular Bundles In a ring

Root Type Taproot

Floral Parts In multiples of 4 or 5

Present (woody trees,

Secondary Growth
shrubs)

Beans, Pea, Mustard,

Examples
Mango
 Examples from NCERT
Group Example Key Feature

Parallel venation,
Monocot Maize
fibrous root

Fibrous root, scattered

Monocot Grass
bundles

Reticulate venation,
Dicot Mango
taproot

Taproot, flower with 5

Dicot Pea
petals

Unique Features of Angiosperms

Feature Description

Enclosed Inside ovary, unlike

Ovules gymnosperms

Specialized structures for

Flowers
sexual reproduction

Protect seeds and help in

Fruits
dispersal

Double Fusion of two male gametes

Fertilization with egg and polar nuclei

Nutritive tissue, triploid,

Endosperm
formed after fertilization
 Comparison: Angiosperms vs Gymnosperms

Characteristic Angiosperms Gymnosperms

Naked, on cone
Seed Type Enclosed in fruit
scales

Flower Presence Present Absent

Fruit Formation Present Absent

Double
Present Absent
Fertilization

Exposed on
Ovule Position Inside ovary
megasporophyll

Endosperm Post-fertilization Before fertilization

Formation (triploid) (haploid)

Economic Importance of Angiosperms

Use Examples

Rice, Wheat, Maize, Fruits,

Food
Vegetables

Fiber Cotton, Jute

Cinchona (quinine), Poppy

Medicine
(morphine)

Timber Teak, Sal, Rosewood

Beverages Tea, Coffee

 Use Examples

Ornamentals Rose, Lily, Tulip

Key NEET Points

Concept Important Notes

Dominant Plant
Angiosperms
Group

Seed Enclosure Inside fruit

Reproductive
Flower
Structure

Pollination Mode Insects, wind, animals, self

Double fertilization (zygote

Fertilization Type
+ endosperm)

Endosperm Triploid, nutritive tissue

Monocot vs Based on cotyledons, leaf

Dicot venation, flower parts

Mango, Maize, Rice, Pea,

NEET Examples
Grass

Practice MCQs (With Answers)

1.​ Angiosperms differ from gymnosperms by:​

Presence of flowers and fruits
 2.​ Double fertilization results in:​
Zygote and endosperm
3.​ Endosperm in angiosperms is:​
Triploid
4.​ Which of the following is a dicot plant?​
Mustard
5.​ Monocots have:​
Parallel leaf venation and fibrous roots

Summary Table

Feature Angiosperms

Seed Enclosed in fruit

Flower Present

Double
Present
Fertilization

Vascular Tissues Advanced (with vessels)

Dominant Phase Diploid sporophyte

Cotyledons Mono (1) or Dicot (2)

Wind, water, insect,

Pollination
animal

Food, fiber, medicine,

Economic Use
timber
 Alternation of Generations
Alternation of generations is a fundamental biological process seen in plants and
some algae, where two distinct multicellular stages alternate to complete the life
cycle.

●​ It refers to the regular alternation between a haploid (n) gametophyte

generation and a diploid (2n) sporophyte generation.
●​ Each generation produces the other by means of sexual or asexual reproduction.

Why is it important ?

●​ It allows plants to reproduce sexually while adapting to environmental conditions.

●​ It increases genetic variation through meiosis and fertilization.
●​ It ensures survival across diverse habitats by alternating between two different
forms.

Definition
Alternation of Generations:​
The biological phenomenon in plants where two distinct multicellular generations,
the haploid gametophyte and the diploid sporophyte, alternate with each other
in a life cycle.

●​ The gametophyte produces gametes by mitosis.

●​ The sporophyte produces spores by meiosis.

Life Cycle Basics

Chromosome
Generation Function Produces
Number

Produces gametes Gametes

Gametophyte Haploid (n)
(male/female) (n)

Produces spores via

Sporophyte Diploid (2n) Spores (n)
meiosis
Types of Life Cycles Based on Alternation of Generations
There are three main types of life cycles, differentiated by which generation is
dominant and how they alternate:

Haplontic Life Cycle

●​ Dominant generation: Haploid (gametophyte)

●​ Sporophyte is usually single-celled or very short-lived.
●​ Spores germinate to form gametophyte.
●​ Fertilization produces a zygote which quickly undergoes meiosis to form spores
again.
●​ Common in algae and fungi.

Example: Chlamydomonas (a green alga)

Diplontic Life Cycle

●​ Dominant generation: Diploid (sporophyte)

●​ Gametophyte is single-celled or very short-lived.
●​ Gametes are produced by meiosis in the sporophyte.
●​ Zygote grows into the sporophyte.
●​ Common in animals and some algae.

Example: Humans (animals), some algae

Haplo-diplontic Life Cycle (Alternation of Generations in True Sense)

●​ Both gametophyte and sporophyte are multicellular.

●​ One generation is dominant depending on the plant group.
●​ Fertilization produces a diploid zygote → sporophyte.
●​ Sporophyte produces haploid spores by meiosis → gametophyte.
●​ This is the true alternation of generations seen in most plants.

Examples:
 Dominant
Plant Group Description
Generation

Sporophyte depends
Bryophytes Gametophyte
on gametophyte

Independent
Pteridophytes Sporophyte
gametophyte

Gymnosperm Gametophyte
Sporophyte
s reduced

Gametophyte highly
Angiosperms Sporophyte
reduced

Detailed Comparison Table of Life Cycles

Diplontic Life Haplo-diplontic Life

Feature Haplontic Life Cycle
Cycle Cycle

Dominant Haploid Diploid Both (varies with

Generation (Gametophyte) (Sporophyte) plant group)

Gametophyte Sporophyte
multicellular, multicellular,
Multicellularity Both multicellular
sporophyte gametophyte
unicellular or absent unicellular

Sporophyte
Zygote undergoes Sporophyte
Spore produces
meiosis to form produces spores by
Production gametes directly
spores meiosis
by meiosis

Bryophytes,
Humans, some Pteridophytes,
Example Chlamydomonas
algae Gymnosperms,
Angiosperms
 Diplontic Life Haplo-diplontic Life
Feature Haplontic Life Cycle
Cycle Cycle

Gametes → Fertilization →
Zygote → meiosis →
Fertilization fertilization → zygote →
spores
zygote sporophyte

Germinate into Gametes Spores germinate

Spores
gametophyte produced directly into gametophyte

NEET-Level Practice Questions

1.​ What is the dominant generation in bryophytes?​

Answer: Gametophyte
2.​ In which type of life cycle is the sporophyte unicellular?​
Answer: Haplontic
3.​ Which plant group shows diplontic life cycle?​
Answer: Humans (animals)
4.​ Name two plant groups with haplo-diplontic life cycle.​
Answer: Pteridophytes, Angiosperms
5.​ What type of spores does the sporophyte produce?​
Answer: Haploid spores via meiosis