11B03

Kingdom Plantae

Realm of the Green!

11B03 Plant Kingdom

Learning objectives

​

Algae

Bryophyta

Pteridophyta

Gymnosperms

Angiosperms

Plant life cycles and Alternation of Generations

Introduction

Defining characters of plants:

Chlorophyll concentrated in chloroplasts, as seen through a light microscope.

Chemical structure of cellulose.

Plants show sessile habit.

​

​

11B03.1

Algae

11B03.1.1

CV1

Introduction and defining characters

Defining characteristics

​

​

​

Algal growth on a damp wall

A typical thallus structure.

Algal growth on a ground sloth. Notice the greenish fur color due to algal invasion.

Forms and Size

Chlamydomonas

Spirogyra

Giant Kelp forest. They grow to be about 100m in length.

Methods of reproduction

Algae

Vegetative Reproduction

Reproduction in

Asexual Reproduction

Sexual Reproduction

Fragmentation

Zoospores

1. Isogamy
2. Anisogamy
3. Oogamy

Sexual Reproduction in Algae

Isogamy in Chlamydomonas

Anisogamy in Chlamydomonas (some species)

Oogamy in Volvox

Commercial and Environmental Uses of Algae

Algae perform most of the CO2 fixation in the world.

Laminaria is eaten as a food across the globe.

Algin from brown algae is used as a hydrocolloid.

More uses of Algae

Gelidium

Agar

Gels and Jellies

Chlorella is used as a food by astronauts.

Classification of Algae

Chlorophyceae

Phaeophyceae

Rhodophyceae

Concept Test

​

Ready for a challenge?

Q. The type of reproduction where one of the gamete is non-motile and the other one is smaller and motile is called

(a) Anisogamy

(b) Autogamy

(c) Oogamy

(d) Isogamy

Pause the video

(Time Duration: 2 minutes)

Sol. (c) Oogamy. Oogamy is a type of sexual reproduction in which the female gamete (ovum) is large non-motile and male gamete (sperm) is small and motile.

11B03.1.2

CV2

Chlorophyceae

Chlorophyceae: The Green Algae

Appear green due to dominance of chlorophyll a & b.

Have varying chloroplast shapes. Ribbon shaped in Spirogyra.

Pyrenoids (storage bodies) may contain proteins, lipids or starch.

Cell wall is rigid with an inner layer of cellulose and an outer layer of pectose.

Reproduction

Algae

Vegetative Reproduction

Reproduction in Chlorophyceae

Asexual Reproduction

Sexual Reproduction

Fragmentation

Zoospores

1. Isogamy
2. Anisogamy
3. Oogamy

Examples of green algae

Chlamydomonas

Volvox

Ulothrix

Concept Test

​

Ready for a challenge?

Q. Which of the following is commonly known as Pond Silk?

​

(a) Ulothrix (b) Chara

(c) Spirogyra (d) Volvox

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (c) Spirogyra. Its common names include Pond Silk, Blanket Weed and Mermaid’s Tresses.

​

​

11B03.1.3

CV3

Phaeophyceae

Phaeophyceae: The brown algae

Appear brown due to presence of Fucoxanthin and Xanthophylls. Photosynthetic pigments are chl a & c

Predominantly marine. Stored food in the form of laminarin and mannitol.

Cellulosic cell wall covered with algin

Body type of brown algae

Thallus of brown algae show a low-key differentiation.

Reproduction in Phaeophyceae.

• They show vegetative, asexual and sexual reproduction same as Chlorophyceae.
• Their asexual spores and gametes are bi-flagellated and pyriform (pear-shaped).

​

​

Sometimes, fertilization occurs within oogonium.

Examples of Phaeophyceae

Ectocarpus

Laminaria

Sargassum

Concept Test

​

Ready for a challenge?

Q. Find the odd one out with respect to Phaeophyceae?

​

(a) Stipe (b) Rhizoid

(c) Frond (d) Holdfast

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

Sol. (b) Rhizoid. Rhizoids act as primordial roots in some species of bryophytes.

11B03.1.4

CV4

Rhodophyceae

Rhodophyceae: The Red Algae

Appear red due to abundance of r-phycoerythrin. Photosynthetic pigments include chl a & d

Mostly marine. They live in both littoral and benthic zones of sea.

Thallus is differentiated and multicellular

Reproduction in Rhodophyta

Vegetative reproduction by Fragmentation

Asexual reproduction take place by non-motile spores

Sexual reproduction is almost always oogamous

Note: Oogamy is followed by complex post-fertilization developments

Examples of Rhodophyceae

Polysiphonia

Gracilaria

Porphyra

Comparing the three algal classes

Concept Test

​

Ready for a challenge?

Q. Which of the following is the reserved food material of Rhodophyceae?

​

(a) Mannitol (b) Floridian Starch

(c) Laminarin (d) Paramylum Starch

​

​

Pause the Video

​

( Time Duration: 2 minutes)

​

​

​

​

Sol. (b) Rhodophyceae. Floridian starch which is structurally quite similar to glycogen and amylopectin is the reserve-food material of the red algae.

Recall Test

​

Ready for a bigger challenge?

Questions-

Q. 1 Which of the following almost always show oogamous reproduction?

(a) Chlorophyta (b) Phaeophyta

(c) Rhodophyta (d) All of these.

​

Q.2 Chlorophyta contains which of the following pigments in abundance?

(a) Chlorophyll a & c (b) Chlorophyll a & b

(c) Chlorophyll a & d (d) None of the above.

​

Q.3 Which one of the following is predominantly marine?

​

(a) Polysiphonia

(b) Gracilaria

(c) Chlamydomonas

(d) Both (a) & (b)

Q. 4 Find the odd one out-

​

(a) Batrachospermum

(b) Gelidium

(c) Chara

(d) Gracilaria

​

Q.5 Which one of the following is a colonial algae?

​

(a) Volvox

(b) Chlamydomonas

(c) Ulothrix

(d) Laminaria

Answers-

Sol.1 (c)

Sol.2 (b)

Sol.3 (d)

Sol.4 (c)

Sol.5 (a)

Summary/ Note-making

• Plant kingdom comprises of photosynthetic, eukaryotic, cellulosic cell-walled and mostly sessile organisms.
• Blue-green algae, which were formerly placed among plants, are now classified under a different kingdom Monera along-with bacteria.
• Kingdom Plantae is classified as algae, bryophyta, pteridophyta, gymnosperms, angiosperms.
• Algae are chlorophyll bearing, thallic, primitive and aquatic plants that require water for reproduction.
• They show high variation in size and form from a unicellular Chlamydomonas to giant aquatic Kelp forests.
• Algae show vegetative (via fragmentation), asexual (via zoospores) and sexual form of reproduction.
• Sexual reproduction can be of isogamous, anisogamous or oogamous type.

Summary/ Note-making

• Algae is responsible for at-least half of the total carbon fixation of the planet by photosynthesis.
• They are the primary producers of energy-rich compounds which is required by aquatic consumers.
• Laminaria and Sargassum are widely consumed as food.
• Agar, a gelling substance extracted from Gelidium and Gracilaria is used in preparing jellies and ice-creams.
• Algin and carrageen are hydrocolloids obtained from brown and red algae respectively.
• Chlorella and Spirullina are protein-rich algae used as food supplements.
• Algae are classified into three main classes: Chlorophyta, Phaeophyta, Rhodophyta.

Summary/Note-making

• Chlorophyceae a.k.a. Green algae is most familiar algae with chlorophyll a&b present in chloroplasts. Their reserve food is starch or protein located in pyrenoids.
• Examples- Chlamydomonas, Spirogyra, Volvox, Ulothrix.
• Phaeophyceae a.k.a. Brown Algae contain pigments fucoxanthin, xanthophylls and chlorophyll a&c. Reserve food material is mannitol and laminarin.
• Examples- Laminaria, Sargassum, Ectocarpus, Dictyota.
• Rhodophyceae a.k.a. Red Algae has r-phycoerythrin for red color and chlorophyll a&d. Their reserve-food material consists of Floridian Starch.
• Examples- Porphyra, Polysiphonia, Gelidium, Gracilaria.

11B03.2

Bryophyta

11B03.2.1

CV1

Defining Characters

Bryophytes: Amphibians of Plant Kingdom

They grow on soil but require aquatic medium for sexual reproduction.

They flourish in moist and shaded hilly regions.

Bryophytic thallus is mildly differentiated.

Introduction

Typical body plan of a bryophyte.

Sporophyte is parasitic on gametophyte which is haploid in nature and dominant.

More about bryophytes

Male sex organ, Antheridium (plural. Antheridia) of a moss. They produce biflagellate antherozoids.

Female sex organ (Archegonium) showing

1. Egg Cell
2. Neck

Reproduction cycle of Bryophytes

Economic importance of bryophytes

Sphagnum

Peat moss

Sphagnum stores a large amount of water, hence used to transport living material.

Classification of Bryophytes

Bryophyta

Liverworts

Mosses

Concept Test

​

Ready for a challenge?

Q. Which of the following is correct for body habit of bryophytes?

​

(a) Sporophyte is diploid and parasitic on gametophyte.

(b) Gametophyte is haploid and parasitic on sporophyte.

(c) Both sporophyte and gametophyte are free-living and diploid.

(d) None of the above.

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

Sol. (a) Sporophyte is diploid in bryophytes and is always parasitic on the gametophyte.

​

​

​

​

11B03.2.1

CV2

Liverworts

Liverworts: Introduction

They grow on marshy areas like tree logs, river banks, damp soil.

Plant body is a flat, dorsiventral thallus close to the substrate.

Reproduction in Liverworts

Gemma cups

Life cycle of Liverworts

Examples of Liverworts

Marchantia

Scapania

Concept Test

​

Ready for a challenge?

Q. Gemma cup in Liverworts are used for-

​

(a) Sexual reproduction (b) Chemotaxis

(c) Protection of spores (d) Asexual reproduction

​

​

​

Pause the Video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (d) Asexual reproduction. Gemma cups grow on thallus and detach to grow into new individuals.

11B03.2.2

CV3

Mosses

Mosses: Introduction

The first stage protonema, develops from a single diploid spore

The second leafy stage, attached to soil by rhizoids and bearing sex organs.

Reproduction in Mosses

Examples of Mosses

Funaria

Sphagnum

Concept Test

​

Ready for a challenge?

Q. Which of the following is present in mosses but absent in liverworts?

​

(a) Rhizoids (b) Gemmae

(c) Leafy Gametophyte (d) Spores

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (c) Leafy Gametophyte. Liverworts possess a thallic, flat, dorsiventral and closed to substrate.

Recall Test

​

Ready for a bigger challenge?

Q.1 Why are bryophytes called amphibians of plant kingdom?

(a) They live in both aquatic and terrestrial habitats.

(b) They require aquatic medium for successful fertilization of gametes.

(c) They perform gaseous exchange through outer layering.

(d) They are famous as insectivorous plants.

​

Q.2 Under-developed, branched stage of mosses that develops from a diploid spore is called-

(a) Leafy Stage (b) gametophyte

(c) Protonema (d) None of the above

​

Q.3 What is the nature and number of antherozoids produced by antheridium?

(a) Biflagellate and multiple. (b) Uniflagellate and 2.

(c) Multiflagellate and 2. (d) Non-motile and single.

Questions-

Q.4 Which of the following is used to make the fuel called as peat moss?

​

(a) Funaria (b) Marchantia

(c) Sphagnum (d) Scapania

​

Q.5 What is the female part of gametophyte in bryophytes known as?

​

(a) Archegonium (b) Antheridium

(c) Embryo sac (d) None of the above

​

Answers-

​

Sol. 1 (b) They require aquatic medium for successful fertilization of gametes.

Sol. 2 (c) Protonema.

Sol. 3 (a) Biflagellate and multiple.

Sol. 4 (c) Sphagnum.

Sol. 5 (a) Archegonium.

Summary/Notes-making

• Bryophytes are also nicknamed amphibians of plant kingdom.
• They grow on soil but require an aquatic medium to successfully perform sexual reproduction.
• They grow in damp and moist environments like marshes, wet soil, tree logs, barks, walls where water is easily accessible.
• They are one of the first organisms to grow on the rocks/soil during plant succession.
• The plant body is erect, thallus like and is attached to the substratum by the help of unicellular rhizoids.
• The main plant body, called the gametophyte is haploid and produces gametes.
• The sex organs (antheridium and archegonium) are multicellular.
• Antherozoids (male gametes) are released in water where they fuse with the egg cell in archegonium and produce a diploid zygote.
• Zygote undergoes division to form a diploid sporophyte.

Summary/Note-making

• Sporophyte is attached to the gametophyte and draws nourishment from it.
• Some of the sporophytic cells undergo reductional division (meiosis) to release haploid spores.
• These spores germinate to produce gametophyte.
• Sphagnum is used as a fuel after turning into peat moss.
• Since it holds a good amount of water, sphagnum is also used for transportation of living material.
• They are one of the first to invade soil/rocks during eco succession.
• Bryophytes are classified into Liverworts and Mosses.
• Liverworts have a flat dorsiventral thallus which is closed to the surface. They grow in marshy areas like river banks.
• Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialised structures called gemmae.
• The gemmae become detached from the parent body and germinate to form new individuals.

Summary/Notes-making

• During sexual reproduction, male and female sex organs are produced either on the same or on different thalli.
• After meiosis, spores are produced within the capsule of sporophyte. These spores germinate to form free-living gametophytes.
• Mosses exhibit a protonema stage and a leafy stage during their life. The leafy stage bears sex organs.
• Vegetative reproduction is by fragmentation and budding.
• Gametes are released from gametophytes.After fertilisation, the zygote develops into a sporophyte, consisting of a foot, seta and capsule.
• The capsule contains spores. Spores are formed after meiosis. Spore dispersal and settlement results in formation of a new gametophyte.

11B03.3

Pteridophyta

11B03.3.1

CV1

Defining Characters

​

​

Pteriodophytes: First Vascular Plants

Mostly used as ornamental plants.

Some sporophylls might develop distinct cones or strobilus (plural. strobili) or cones.

Two types of leaves in pteridophytes

Sporophyte (2n) is the dominant phase of pteridophytes and produces spores.

Gametophyte (n) is small, free-living, thalloid and photosynthetic. A young sporophyte can also be seen in the picture.

More about Pteridophytes

Classification of Pteridophytes

Eg. Psilotum

Eg. Selaginella

Eg. Equisetum

Eg. Dryopteris

Concept Test

​

Ready for a challenge?

Q. Some pteridophytes form a special structure for spore-bearing called-

(a) Strobilus (b) Sorus

​

(b) Frond (d) Sporophyll

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

Sol. (a) Strobilus. Some pteridophytes like Equisetum have their sporophylls modified into cone-shaped structures called strobilli (plural).

11B03.3.2

CV2

Reproduction and Life Cycle.

Reproduction in pteridophytes

Close-up of a sporophyll showing several sporangia. A group of such sporangia is called sorus (plural. sori).

Spores released by a sporangium give rise to gametophyte (n).

Gametophyte produces gametes, upon whose fertilization the sporophyte (2n) is formed from zygote.

Life cycle of a pteridophyte

Pteridophytes: Examples

Equisetum

Dryopteris

Selaginella

Summary/ Note-making-

• The Pteridophytes include horsetails and ferns.
• Pteridophytes are used for medicinal purposes, as soil binders and also frequently grown as ornamental plants.
• They are the first terrestrial plants to possess vascular tissues – xylem and phloem.
• The pteridophytes are found in cool, damp, shady places though some may flourish well in sandy-soil conditions.
• Since pteridophytes only grow in damp, cool and shady places their geographical distribution is limited to specific regions.
• In pteridophytes, the main, dominant plant body is a sporophyte which is differentiated into true root, stem and leaves and is diploid (2n) in nature.
• The leaves in pteridophytes are small (microphylls) as in Selaginella or could be large (macrophylls) as in Dryopteris.
• The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls or in some cases sporophylls may form distinct compact structures called strobili (sing. strobilus) or cones (Selaginella, Equisetum).
• The sporangia produce spores by reductional division (meiosis) in spore mother cells.
• Spores after germination give rise to small, multicellular, free-living, photosynthetic, thallus-like gametophyte which is called prothallus and is haploid (n).
• The gametophytes bear male and female sex organs called antheridia and archegonia, respectively.

Summary/ Note-making-

• Water is required for transfer of antherozoids – the male gametes released from the antheridia, to the mouth of archegonium.
• Fusion of male gamete with the egg present in the archegonium result in the formation of zygote.
• Zygote thereafter produces a multicellular, well-differentiated sporophyte which is the dominant phase of the pteridophytes.
• In majority of the pteridophytes all the spores are of similar kinds; such plants are called homosporous.
• Some of them produce spores of two different kinds - micro (small) and macro (large). They are known as heterosporous. Exempli gratia - Selaginella and Salvinia.
• The megaspores gives rise to female gametophytes and microspores develop into male gametophytes.
• The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution.
• The pteridophytes are further classified into four classes: Psilopsida (Psilotum); Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum) and Pteropsida (Dryopteris, Pteris, Adiantum).

Concept Test

​

Ready for a challenge?

Q. The organ in pteridophytes bearing a cluster of spores called _________ is known as-

​

(a) Sporophyll (b) Sporogenous tissue

(c) Sporangium (d) Sporogonium

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

Sol. (a) Sporophyll. In pteridophytes, the group of spores known as sori (sing. sorus) are adhered to the ventral side of leaf-like appendage called Sporophyll.

​

Recall Test

​

Ready for a bigger challenge?

Q.1 On which of the following bases are algae classified?

(a) Nutrition intake

(b) Habitat

(c) Pigments

(d) None of the above

​

Q.2 What do bryophytes mainly need water for?

(a) Photosynthesis

(b) Fertilization

(c) Respiration and gaseous exchange

(d) Maintaining osmotic potential

​

Q.3 What is the dominant phase in the life of a pteridophyte?

(a) Sporophyte

(b) Gametophyte

(c) Both (a) & (b)

(d) None of the above

Questions-

Q.4 Blue-Green Algae (BGA) are-

(a) Plants

(b) Connecting links between autotrophs and heterotrophs

(c) Photosynthetic Protists

(d) Monerans

​

Q.5 Heterospory is defined as-

(a) Spores from two sporophytes of different species.

(b) Spores from the same sporophyte.

(c) When only macro-spores are generated.

(d) The habit of producing two unequal types of spores (macro and micro).

​

Answers-

Sol. 1 (c) Pigments.

Sol. 2 (b) Fertilization.

Sol. 3 (c) Sporophyte.

Sol. 4 (d) Monerans.

Sol. 5 (d) The habit of producing two unequal types of spores (macro and micro).

11B03.4

Gymnosperms

11B03.4.1

CV1

Introduction and defining characters

Gymnosperms- Plants with Naked Seeds

As depicted, a gymnosperm ovule lacks an outer covering of ovary, which is not the case in angiosperms.

Gymnosperms constitute some of the largest trees in the world. Eg. The Giant Sequoia.

More about Gymnosperms

Gymnosperms usually possess tap root systems with association with mycorrhizal fungi.

Some of them have coralloid roots with symbiotic association with N2 fixing bacteria.

Gymnosperm Morphology

Stem could be unbranched. Eg. Cycas

Or could be branched as in Pinus.

Their thin, needle like leaves help them withstand water loss, high wind and humidity.

Concept Test

​

Ready for a challenge?

Q. Which of the following can be found among the Coralloid roots of gymnosperms?

​

(a) Amoeba (b) Anabaena

(c) Paramoecium (d) Euglenoids

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (b) Anabaena. Nitrogen fixing Cyanobacteria like Anabaena are found in a symbiotic relationship with the coralloid roots.

11B03.4.2

CV2

Reproduction in Gymnosperms

Reproduction in Gymnosperms

(a) Cross section of a microsporangium (male cone) with multiple microsporophyll.

(b) Pollen grains (male gametophyte) visible as tiny spots.

(c) A highly magnified image of a male gametophyte which is highly reduced.

(d) Cross section of a female megasporangium (female cone) showing multiple megasporophyll.

(e) A single ovule can be seen in the cross section of a megasporophyll.

(f) A more magnified view of ovule allows us to spot a Megaspore Mother Cell, Micropyle and a pollen grain.

A megastrobilus showing multiple megasporophylls.

A cluster of microstrobili. The numerous spots depict microsporophylls.

Life Cycle of a gymnosperm.

(A) Habitat of a male Pinus with strobili or cones arranged in a spiral.

(B) Close up of a male inflorescence showing a cluster of strobilus.

(C) Microsporophyll contains 2 pollen sacs (microsporangium) that contains microsporocyte.

​

(meiosis) (mitosis)

Microsporocyte Microspore Pollen grains.

(D) Longitudinal section of a microstrobilus.

1. Microsporophyll
2. Pollen sac showing pollen

(E) Detailed microsporophyll

1. Microsporophyll (2n)
2. Wall of microsporangium

(F) Magnified view of male sporangium.

(G) Magnified view of one pollen grain.

(H) Germinating pollen grain.

The sporophyte (2n), (left) is the dominant phase of gymnosperms. While the gametophyte (n) is highly reduced and contained within sporangia of sporophylls (right) on sporophytes.

Examples of Gymnosperms-

Ginkgo biloba

Sequoiadendrum giganticum

Pinus strobus

Summary/ Note making-

• 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.
• Gymnosperms include medium-sized trees or tall trees and shrubs but one of the gymnosperms, the giant redwood tree Sequoia is one of the tallest tree species.
• The roots are generally tap roots. They remain in a symbiotic association with the fungi Mycorrhiza. Eg. Pinus.
• Some members have coralloid roots which show symbiosis with Nitrogen-fixing bacteria. Eg. Cycas.
• The stems are unbranched (Cycas) or branched (Pinus, Cedrus) and the leaves may be simple or compound. In Cycas the pinnate leaves persist for a few years
• The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind.
• In conifers, the needle-like leaves reduce the surface area. Their thick cuticle and sunken stomata also help to reduce water loss.
• The gymnosperms are heterosporous; they produce haploid microspores and megaspores.
• The two kinds of spores are produced within sporangia that are borne on sporophylls which are arranged spirally along an axis to form lax or compact strobili or cones.
• The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili.
• The microspores develop into a male gametophytic generation which is highly reduced and is confined to only a limited number of cells which is called a pollen grain.

Summary/ Notes making-

• The development of pollen grains take place within the microsporangia.
• The cones bearing megasporophylls with ovules or megasporangia are called macrosporangiate or female strobili.
• The male or female cones or strobili may be borne on the same tree (Pinus) or on different trees (Cycas).
• The megaspore mother cell is differentiated from one of the cells of the nucellus which is protected by envelopes and the composite structure is called an ovule.
• The megaspore mother cell divides meiotically to form four megaspores.
• One of the megaspores enclosed within the megasporangium (nucellus) develops into a multicellular female gametophyte that bears two or more archegonia or female sex organs.
• The multicellular female gametophyte is also retained within megasporangium.
• 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.
• Pollen grain are carried in air currents and come in contact with the opening of the ovules borne on megasporophylls.
• Following fertilisation, zygote develops into an embryo and the ovules into seeds. These seeds are not covered.

Concept Test

​

Ready for a challenge?

Q. Microsporocyte in gymnosperms after _________ division forms-

​

(a) Pollen grain (b) Egg Cell

(c) Nucellus (d) Microspore

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

Sol. (d) Microspore. Microsporocyte undergoes Reductional Division/ Meiosis to give rise to microspore.

Recall Test

​

Ready for a bigger challenge?

Q.1 A Gymnospermic plant-

(a) Exhibits no Vascular Bundles

(b) Bears Flowers

(c) Produces seeds inside cones

(d) Does not produces seeds inside cones

​

Q.2 Microsporophyll produces-

(a) Pollen Grains

(b) Spores

(c) Ovules

(d) None of the above

​

Q.3 Which of the following is monoecious?

(a) Cycas (b) Pinus

(c) Ginkgo (d) Ephedra

Questions-

Q.4 The fertilization in gymnosperms takes place in-

(a) Integuments

(b) Archegonia

(c) Nucellus

(d) None of the above

​

Q.5 The tallest tree in the world is-

(a) Giant Sequoia

(b) Bristlecone Pine

(c) Atropa

(d) Ficus

​

​

Sol.1 (c) Produces seeds inside cones.

Sol.2 (a) Pollen Grains

Sol.3 (b) Pinus

Sol.4 (b) Archegonia

Sol.5 (a) Sequoia

Answers-

11B03.5

Angiosperms

11B03.5.1

CV1

Introduction and Defining Characters

Flowering- The most significant defining character of Angiosperms.

Angiosperms: The Flowering Plants

Pollen Grains and Ovules are developed and borne inside flowers.

The seeds formed after fertilization are enclosed by fruits in Angiosperms.

Mangifera indica (Mango). Family Anacardiaceae

Atropa belladonna (Deadly Nightshade). Family Solanaceae

Pyrus malus (Apple). Family Rosaceae

Some prominent angiosperms with their families

Families and economic importance

Some of the prominent angiosperm families. It is the largest group of plants.

Angiosperms serve as the main producers of food around the planet.

Timber

Medicine

Fuel

Textile

Varying sizes of Angiosperms

Wolffia arrhiza. Smallest angiosperm.

Urtica dioica (Nettle/Bicchhubooti), an average sized herbaceous plant.

Eucalyptus, which could be over 100m tall.

Concept Test

​

Ready for a challenge?

Q. What is the scientific name of Mango?

​

(a) Mangifera indica (b) Magnolia grandiflora

(b) Spondias pinnata (d) Pyrus communis

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (a) Mangifera indica. Mangifera is from the family Anacardiaceae.

11B03.5.2

CV2

Classification, Anatomy and Pollination

​

Classification of Angiosperms

Angiosperms

Dicotyledons

Monocotyledons

Angiosperms having two cotyledons. Eg. Grams

Angiosperms having a single cotyledon. Eg. Grasses.

Stamen: The male sex organ

Anthers produce pollen grains after meiosis that contain male germ cell.

Filament is a stalk by which the anthers are attached in a flower.

Stamen/Carpel: Female sex organs

The central, disc-like structure depicts carpel of a lotus flower.

A simplified structure of an carpel showing embryo sac (female gametophyte).

Every cell in embryo sac is haploid since this entire apparatus is preceded by meiosis. The nuclei of polar cells fuse to form a secondary nucleus (2n).

Pollination

Transfer of pollen from anther to stigma can be done by wind, insects and even bats.

Electron micrograph showing pollen on a stigma.

A germinating pollen containing 2 sperm cells.

Concept Test

​

Ready for a challenge?

Q. Which of the following is not haploid in embryo sac of angiosperms?

​

(a) Synergids (b) Integuments

(c) Secondary Nucleus (d) Egg Cell

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (c) Secondary Nucleus. Two haploid polar nuclei fuse together to form a diploid secondary nucleus.

11B03.5.3

CV3

Reproduction and Fertilization

Double Fertilization

One sperm cell fuses with egg (Syngamy) - Zygote (2n)

​

Second sperm cell fuses with two polar nuclei (Triple Fusion)- Primary Endosperm Nucleus.

Post-Fertilization Events

Ovary develops into Fruit

The Zygote develops into Embryo with one/two Cotyledons. Ovule develops into Seed.

Primary Endosperm Nucleus forms Endosperm (3n) which gives nourishment to embryo.

Life-Cycle of an Angiosperm

Concept Test

​

Ready for a challenge?

Q. What is the result of triple fusion?

​

(a) Endosperm (b) Fruit

(c) Seed (d) PEN

​

​

​

​

Pause the video

(Time Duration: 2 Minutes)

​

​

​

​

Sol. (d) PEN. Primary Endosperm Nucleus is developed from Endosperm.

Recall Test

​

Ready for a bigger challenge?

Questions-

Q.1 The condition where stamen and carpel are present on different flowers is called-

(a) Monoecious (b) Hermaphrodite

(c) Dioecious (d) None of the above

​

Q.2 The female sex organs in angiosperms is called-

(a) Stamen (b) Carpel

(c) Pistil (d) Both (b) & (c)

​

Q.3 Which of the following combination is correct for triple fusion?

(a) 1 polar nucleus, 1 sperm cell and 1 antipodal cell.

(b) 1 sperm cell and 2 polar nuclei.

(c) 2 sperm cells and 1 polar nucleus.

(d) 2 synergids and 1 central cell.

Q.4 What is the landing site of pollen grains during pollination?

(a) Ovary (b) Stigma

(c) Style (d) Corolla

​

Q.5 Nutrition to the developing embryo is provided by-

(a) Endosperm

(b) Cotyledons

(c) Fruit

(d) None of the above.

Answers-

Sol. 1 (c)

Sol. 2 (d)

Sol. 3 (b)

Sol. 4 (b)

Sol. 5 (a)

​

​

Summary/ Notes making-

• In angiosperms or flowering plants, the pollen grains and ovules are developed in specialised structures called flowers and seeds are covered by fruits.
• The angiosperms are an exceptionally large group of plants occurring in wide range of habitats from a tiny 2mm Wolffia to the gigantic 100m Eucalyptus.
• They provide us with food, fodder, fuel, medicines and several other commercially important products.
• They are divided into two classes : the dicotyledons and the monocotyledons.
• The dicotyledons are characterised by having two cotyledons in their seeds while the monocotyledons have only one.
• The male sex organs in a flower is the stamen which consists of a slender filament with an anther at the tip. The anthers, following meiosis, produce pollen grains
• The female sex organs in a flower is the pistil or the carpel which consists of an ovary enclosing one to many ovules.
• Within ovules are present highly reduced female gametophytes termed embryo-sacs whose formation is preceded by meiosis. Hence, each of the cells of an embryo-sac is haploid.
• Each embryo-sac has a three-celled egg apparatus – one egg cell and two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse to produce a diploid secondary nucleus.
• Pollen grain, after dispersal from the anthers, are carried by wind or various other agencies to the stigma of a pistil. This process is called Pollination.

Summary/ Note making-

• The pollen grains germinate on the stigma and the resulting pollen tubes grow through the tissues of stigma and style and reach the ovule.
• The pollen tubes enter the embryo-sac where two male gametes are discharged.
• 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 two fusions, this event is termed as double fertilisation, an event unique to angiosperms.
• The zygote develops into an embryo (with one or two cotyledons) and the PEN develops into endosperm which provides nourishment to the developing embryo.
• The synergids and antipodals degenerate after fertilisation. During these events the ovules develop into seeds and the ovaries develop into fruit.

11B03.6

Plant life cycles & Alternation of generations

11B03.6.1

CV1

Concept of alternation of generation

Cell proliferation fates in plants

Both haploid and diploid cells of a plant body divide by mitosis, which is shown above.

This leads to formation of both sporophyte (2n) and gametophyte (n) in life cycle of plant.

Gametophyte (n)

Gametes (n)

Mitosis

Fusion of Gametes

Zygote (2n)

Mitosis

Zygote (2n)

Sporophyte (2n)

Meiosis

Sporophyte (2n)

Spores (n)

Reductional division

Sporophyte (2n)

Gametophyte (n)

Concept Test

​

Ready for a challenge?

Q. What is the nature of the spores produced by ___________ in Angiosperms?

​

(a) Haploid (b) Diploid

(c) Triploid (d) Polyploid

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (a) Haploid. Sporophyte (2n) produces haploid spores which develop into gametophyte (n).

11B03.6.2

CV2

Types of Life Cycles

Haplontic Life Cycle

Mostly seen in Chlorophyta. Eg. Spirogyra, Ulothrix and some species of Chlamydomonas.

Diplontic Life Cycle

Frequently exhibited by seed bearing plants. Eg. Gymnosperms and Angiosperms.

Haplo-diplontic Life Cycle

Shown by Pteridophytes & Bryophytes.

Concept Test

​

Ready for a challenge?

Q. What type of life-cycle is shown by Ginkgo?

​

(a) Haplontic (b) Diplontic

(c) Haplo-diplontic (d) None of the above

​

​

​

​

Pause the video

(Time Duration: 2 minutes)

​

​

​

​

Sol. (b) Diplontic. All seed-bearing plants follow a diplontic life-cycle.

Recall Test

​

Ready for a bigger challenge?

Questions-

Q.1 Gametophyte undergoes what form of division to produce gametes?

​

(a) Meiosis (b) Mitosis

(c) Fission (d) Parthenogenesis

​

Q.2 Structures produced by __________ that give rise to gametophytes are-

​

(a) Antherozoids (b) Gemmae

(c) Spores (d) Fragments

​

Q.3 The life cycle shown by Funaria is-

​

(a) Haplo-diplontic (b) Diplontic

(c) Haplontic (d) None of the above

Q.4 Find the odd one out?

​

(a) Gnetum (b) Mangifera

(c) Solanum (d) Dryopteris

​

​

Q.5 Which of the following is diplontic?

​

(a) Fucus (b) Polysiphonia

(c) Spirogyra (d) Ectocarpus

Answers-

Sol.1 (b)

Sol.2 (c)

Sol.3 (a)

Sol.4 (d)

Sol.5 (a)

Summary/ Notes making-

• In plants, both haploid and diploid cells can divide by mitosis which leads to the formation of different plant bodies - haploid and diploid.
• The haploid plant body produces gametes by mitosis that represents a gametophyte.
• Following fertilisation the zygote also divides by mitosis to produce a diploid sporophytic plant body. Haploid spores are produced by this plant body by meiosis.
• Spores 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 generations between gamete producing haploid gametophyte and spore producing diploid sporophyte.
• Different plant groups, as well as individuals representing them, differ in the following patterns.
• In haplontic life-cycle Sporophytic generation is represented only by the one-celled zygote. There are no free-living sporophytes. Meiosis in the zygote results in the formation of haploid spores. The haploid spores divide mitotically and form the gametophyte. The dominant, photosynthetic phase in such plants is the free-living gametophyte.

Summary/ Notes making-

• The haploid spores divide mitotically and form the gametophyte. The dominant, photosynthetic phase in such plants is the free-living gametophyte.
• Many algae such as Volvox, Spirogyra and some species of Chlamydomonas represent haplontic pattern.
• In Diplontic, n the diploid sporophyte is the dominant, photosynthetic, independent phase of the plant. The gametophytic phase is represented by the single to few-celled haploid gametophyte.
• All seed-bearing plants i.e. gymnosperms and angiosperms, follow diplontic pattern.
• In Haplo-diplontic condition, both phases are multicellular and often free-living. However, they differ in their dominant phases.
• A dominant, independent, photosynthetic, thalloid or erect phase is represented by a haploid gametophyte and it alternates with the short-lived multicellular sporophyte totally or partially dependent on the gametophyte for its anchorage and nutrition. All bryophytes represent this pattern.

Summary/ Notes making-

• The diploid sporophyte is represented by a dominant, independent, photosynthetic, vascular plant body. It alternates with multicellular, saprophytic/autotrophic, independent but short-lived haploid gametophyte.
• Such a pattern is known as haplo-diplontic life cycle which all pteridophytes exhibit.
• Interestingly, while most algal genera are haplontic, some of them such as Ectocarpus, Polysiphonia, kelps are haplo-diplontic. Fucus, an alga is diplontic.