Plant Kingdom Notes for NEET Biology Chapter 3

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Last Updated on July 9, 2024 by sanjjeett

Hello students, we are providing notes for NEET biology. NEET (National Eligibility cum Entrance Test) is one of the most challenging medical entrance exams in India. A thorough understanding of the syllabus is crucial for scoring well. This article focuses on “Plant Kingdom” chapter in the biology syllabus for NEET. It is a part of “Important Notes for NEET Biology” Series.

Chapter	Plant Kingdom
Unit	Diversity of Living Organisms
Type of Material	Notes
Exam	NEET
Class	11
Subject	Biology
Branch	Botany
Useful for	Students Preparing for NEET
Important definitions	Provided
FAQs provided	Yes
Important Link	NEET Biology Important Notes

NEET BIOLOGY CHAPTER 3 PLANT KINGDOM NOTES

What are Plants

Plant kingdom classification has changed a number of times over the years. For instance, blue-green algae were once considered to be part of the plant kingdom, but today, they are classified under Kingdom Eubacteria. Similarly, lichen was once considered a plant; however, they are composite organisms. In other words, lichens are comprised of two individual organisms a fungus and a plant. Historically, organisms that could not be classified under animals were grouped under plants.

Whittaker classified the whole living organism into five kingdoms based on the complexity of cell structure (Prokaryotic and Eukaryotic), the complexity of the body (unicellular and multicellular), and mode of nutrition (autotrophs and heterotrophs).

Classification of the Plant Kingdom

All the classification systems, starting from that of Aristotle to the 20thcentury, can be divided into three types:

• Artificial System: In this system, the classification is based on few morphological characters. Theophrastus, Pliny, and Linnaeus used an artificial system of classification.
• Natural System: In this system, the classification is based on all the important related characters. Both external and internal. Bentham and hooker, Adanson, Candolle used a natural system of classification.
• Phylogenetic System: Classification based on the evolutionary relationship of plants. The use of phylogeny for classification was done by Eichler, Blessy.

Numerical Taxonomy

Taxonomy based on statistical methods with equal importance using computers.

Cytotaxonomy

Taxonomy that is based on cytology or structure of the cell (chromosome number, shape, behaviour, etc).

Chemotaxonomy

Taxonomy based on chemical constituents of plants (nature of the protein, DNA sequence, taste, smell, etc).

Eichler Classification

The classification of Plant kingdom depending on flowering. Divided into two-Cryptogamae (non-flowering, seedless plants) and Phanerogamae (flowering, seed-bearing plants).

Based on the Plant Body Cryptogamae is divided into Thallophyta, Bryophyta, and Pteridophyta.

• Thallophyta: The plant body is thallus-like (undifferentiated plant body).
• Bryophyta: Plant body with a root-like structure, stem-like structure, vascular tissues are absent).
• Pteridophyta: The plant body is differentiated into true root, stem, and leaves. Vascular

Thallophytes Again Divided Into:

• Algae (pigmented thallophytes).
• Fungi (non-pigmented thallophytes).
• Lichens: Symbiotic association between algae and fungi.

Phanerogamae is Divided Into Two:

• Gymnosperms (naked seed plants)
• Angiosperma (covered seeded plants)

Angiosperms Are Again Divided Into Two:

• Monocots (bearing single cotyledon, fibrous root system, and parallel venation).
• Dicots (have two cotyledons, taproot system, and reticulate venation).

Algae

1. Phycology: Branch of Biology that deals with the study of algae

Phycos = Seaweed

Logos = Study

• Fritch – Father of phycology.
• M.O.P. Iyengar is the father of Indian phycology.

Algal members are pigmented thallophyte

Habitat

Hydrophytes: Water is their habitat. In aquatic habitat:

• Freshwater (Spirogyra) and marine (Sargassum).
• Floating- Chlamydomonas, Spirogyra
• Benthophytes – These plants remain attached to the bottom of their habitat. Example Chara (stoneworts) 
• Xerophytes: Their habitat is desert.
• Mesophytes- They grow in medium habitats.
• Epiphytes- They grow on plant body (Cladophora)
• Epizoic- growing on the animal body (Trichophillus)
• Lithophytes- They grow on rocks.
• Halophytes- They grow in salty areas.
• Moist soil-terrestrials (Fritschiella).

Plant Body

• The vegetative plant body of algae is a haploid gametophyte.
• They may be unicellular, flagellated (Chlamydomonas), or non-flagellated (Chlorella).

Multicellular:

• Coenobium- It is a colony with a fixed number of cells and also the division of labor is fixed. E.g.: Volvox.
• Aggregation-indefinite colony. E.g., Tetraspora
• Filamentous-unbranched. E.g.: Ulothrix
• Filamentous branches. E.g.: Cladophora
• Siphonous- multinucleate. E.g.: Vaucheria
• Parenchymatous. E.g.: Ulva the,
• Branched like higher plants. E.g.: Sargassum, Chara

Nutrition:

• Autotrophs – Photosynthetic (most of them)
• Parasitic forms (rare). E.g.: Cephaleuros.

Pigments:

• Chlorophyll- a, b, c, d.
• Carotenoids- carotene and xanthophyll-fucoxanthin are dominating pigments in brown algae.
• Phycobillins- phycocyanin and phycoerythrin.

Reproduction

Vegetative reproduction: Reproduction Using the Vegetative Parts.

Different Types are:

• Fission
• Fragmentation
• Budding
• Tubers
• Gemmae

Asexual Reproduction: Without the Fusion of Gametes.

Mainly by:

• Zoospores within sporangia
• Aplanospores
• Akinete
• Hypnospores
• Endospore
• Exospore 
• Monospore
• Auxospore.

Palmella Stage

In this stage of asexual reproduction the spores become colonial and appear like the algae named Palmella. E.g.: Ulothrix, Chlamydomonas.

Sexual Reproduction

Homogametes: Similar gametes.

Heterogametes: Dissimilar gametes.

Isogamy: Fusion of morphologically and physiologically similar gametes.  Isogamy- flagellated (Chlamydomonas) and non-flagellated (Spirogyra).

Anisogamy: Fusion of morphologically or physiologically dissimilar gametes. Morphologically dissimilar gametes’ fusion occurs in Chlamydomonas. Physiologically dissimilar gametes’ fusion occurs in Spirogyra.

Oogamy: It is the fusion of morphologically and physiologically dissimilar gametes that are small motile male gamete and large nonmotile female gamete. E.g.: Fucus, Volvox.

Exceptional Cases:

Unicellular antheridium and oogonium. E.g.: Oedogonium.

Special Reproductive Structures:

Conceptacles- E.g.: Sargassum

Globule (antheridium) and nucule (oogonium) E.g.: Chara

Conjugation

A special type of sexual reproduction called conjugation is found in spirogyra. The life cycle exhibits two phases-haploid and diploid and some of them exhibit alternation of generation. The diploid phase is alternated with the haploid phase.

Classification of Algae

They are classified into three:

• Chlorophyceae
• Phaeophyceae
• Rhodophyceae

Chlorophyceae: In Chlorophyceae, the plant body is unicellular as in Chlamydomonas or colonial as in Volvox or filamentous as in Spirogyra.

Different Shapes for the Chloroplast:

1. Ribbon shaped and spiral in Spirogyra

• Girdle shaped in Ulothrix

• Cup shaped chloroplast in Chlamydomonas.

• Star-shaped in Zygnema.

• Disc-shaped in Caulerpa

• Reticulate in Oedogonium.

• Photosynthetic pigments are chlorophyll a and b.
• Food is stored in the form of starch and some are stored in the form of oil droplets.
• Pyrenoids are present, which are the storage bodies.
• The inner layer of the cell wall is made up of cellulose and the outer layer is made up of pectose.

The members reproduce:

• Vegetatively by fragmentation
• Asexually by flagellated zoospores 
• Sexually by isogamy, anisogamy, and oogamy.

Common Chlorophyceae members are: Chlamydomonas, Chlorella, Volvox, Ulothrix, Ulva, Caulerpa, Chara, Acetabularia etc.

Brown Algae or Phaeophyceae

• They are marine.
• Simple branched and filamentous as in Ectocarpus, or flat ribbon-shaped in Sargassum, Laminaria, Fucus, etc.
• The giant brown algae Kelps are the largest sea plants, some are free-floating as in Sargassum and some are epiphytes on other plants like Ectocarpus.

The Plant Body has Three Parts:

• Fixing structures called a holdfast.
• The stalk-like structure called a stipe.
• The leaf-like structure is called a frond.

Rhodophyceae (Red Algae)

Red algae Rhodophyceae (red algae) include members like Porphyra, Porphyridium, Polysiphonia (multi-axial body), Batrachospermum (Frog spawn alga), Gelidium, Gracilaria, Gleopeltis, Chondrus, Corallina, Harveyella (colourless parasitic red alga). Habitat Mostly they are marine. Found in warmer oceans.

Economic Importance of Algae:

• In the food chain algae are the primary producers. The basis of the food cycles of all aquatic animals is formed by the algae.
• On earth, half of the total carbon dioxide fixation is carried out by algae through the process of photosynthesis.
• In the purification of air and water it plays a very important role.
• Some algae are edible. E.g.: Chlorella, Laminaria, Porphyra, Sargassum, Ulva, Spirulina.  
• Some algae are used as fodder. E.g.: Laminaria, Sargassum, Fucus.
• It also acts as a food supplement for space travelers. E.g.: Chlorella, Spirulina.
• From red algae, algin and carrageenan are obtained which are water-holding substances or hydrocolloids.
• Agar is obtained by Gelidium and Gracilaria. It is used to grow microorganisms.
• Used in the preparation of culture medium in tissue culture experiments.
• It has medicinal values as antibiotics are prepared from them.
• Also used as a source of minerals- Polysiphonia, Laminaria
• Has importance in biological research: Chlorella, Acetabularia.
• E.g.: Chlorella, Polysiphonia.

Common Names of Algae:

• Water silk-Spirogyra
• Sea lettuce- Ulva
• Umbrella plant-Acetabularia (Largest unicellular algae)

Bryophytes

• Simplest non-vascular land plants with undifferentiated plant bodies.
• Bryology: Study of Bryophytes.
• Hedwig: Father of bryology.
• S.R. Kashyap: Father of Indian bryology.
• The bryophytes are also called the amphibians of the plant kingdom due to their unique characteristics.
• Bryophytes grow in dense patches on moist shady places like walls, damp soil, tree trunks, etc.

Features

• Habitat: Mainly terrestrial but some are aquatic. E.g.: Riccia fluitans
• Epiphyllous E.g.: Radula
• Plant body Thallus and Prostate. E.g.: Riccia, Anthoceros, Marchantia or Erect. E.g.- Moss.
• Root-like structures called rhizoids help in fixing them in the soil.
• The body of the plant is differentiated into stem-like and leaf-like structures.
• Vascular tissues are absent.
• Vegetative reproduction occurs by fragmentation, budding, tubers, etc.
• Asexual reproduction occurs by Gemmae- asexual buds in liverworts.
• Sexual reproduction occurs. The vegetative plant body acts as the gametophyte and all the members are homosporous.
• Multicellular sex organs are present that are found in clusters.
• The club-shaped antheridium is the male reproductive organ and it produces biflagellate antherozoids which are motile too.
• The flask-shaped archegonium is the female reproductive organ and it produces the egg.
• To form the zygote the antherozoid fuses with the egg.
• The sporophyte is not free-living and it derives nutrients from the photosynthetic gametophyte.
• After meiosis, the haploid spores are formed in the sporophyte and the spore germinates to form the gametophyte.
• Alternation of generation is present where the haploid phase alters with the diploid phase.
• Both the phases are multicellular.
• The gametophyte is the dominant photosynthetic free-living stage.
• The sporophyte is short-lived and it highly depends on the gametophyte.
• For fertilization, water is very much essential.

Classification of Bryophytes: It has three classes.

• Hapticospida (liverworts).
• Anthocerotopsida (Hornworts).
• Bryopsida. (Moss).

Hepaticopsida or Liverworts

A class of lower green plants called liverworts that belong to the division Bryophyta. The class Hepaticopsida, also called Marchantiopsida, comprises the liverworts, which are nonvascular land plants. Although there is a great diversity of external form, most of the gametophytes (gamete-producing plants) are dorsoventrally differentiated.

Bryopsida (Moss)

• They are higher bryophytes.
• The gametophyte consists of two stages-protonema and the leafy stage.
• Protonema is green filamentous, branched, creeping structures that directly develop from the spore on germination, and they also bear branched rhizoids and lateral buds.
• The leafy stage is developed as a lateral bud from the secondary protonema.
• The plant body consists of root-like, stem-like, and leaf-like structures. Eg: Funaria.
• Rhizoids are multicellular and branched also.
• The leafy stages bear the sex organs.
• Vegetative reproduction occurs by the process of fragmentation  and budding in the secondary protonema.

Economic Importance:

• They are used as food by herbaceous animals.
• Sphagnum (Moss) occurs in the form of peat and is used as fuel.
• Because of its water holding capacity, the mosses are also used for the trans-shipment of living material.
• Moses also prevents soil erosion.
• They are the first colonizers on barren rocks along with lichens.
• For the growth of the higher plants or succession, they decompose rocks for making substrate.

Pteridophytes

• They are the first terrestrial plant to bear vascular tissue such as xylem and phloem. So they are also called vascular cryptogams.
• Commonly known as a botanical snake.
• The plant body is differentiated into true root, stem, wind-needle-like, and leaf.
• The plant body is the sporophytic generation.
• The stem is rhizomatous and they regenerate when aerial parts are destroyed.
• Leaves may be small known as microphyll as in Selaginella or large known as macrophyll as in ferns.

Pteridophytes are further classified into four classes:

• Psilopsida (Psilotum)
• Lycopsida (Selaginella)
• Sphenopsida (Equisetum)
• Pteropsida (Pteris).

Economic Importance:

• Some members are Medicinal: Dryopter is Helps in Soil binding & Used as Ornamental plants.
• Edible plants: Marcelia Used in Crop rotation- Azolla & Helps in Symbiotic nitrogen fixation.
• Play an important role in the succession of plants on bare rocks or soil.
• Sphagnum is used to keep seedlings in gardens and also in keeping cut plant parts moist during transportation and propagation.

Common Names:

• Creeping pine/ Club moss- Lycopodium
• Spike moss (Resurrection plant- Selaginella
• Water fern- Azolla (smallest pteridophyte)
• Walking fern (Maiden Hall fern)- Adiantum
• Adder’s tongue fern- Ophioglossum
• Fossil pteridophyte- Cooksonia
• Leafless Pteridophyte- Psilotum
• Horsetail- Equisetum

Gymnosperm

The word “Gymnosperm” comes from the Greek words “gymnos”(naked) and “sperma”(seed), hence known as “Naked seeds.” Gymnosperms are the seed-producing plants, but unlike angiosperms, they produce seeds without fruits. These plants develop on the surface of scales or leaves, or at the end of stalks forming a cone-like structure.

Gymnosperms belong to kingdom ‘Plantae‘ and sub-kingdom ‘Embryophyta’. The fossil evidence suggested that they originated during the Paleozoic era, about 390 million years ago.

Basically, gymnosperms are plants in which the ovules are not enclosed within the ovary wall, unlike the angiosperms. It remains exposed before and after fertilisation and before developing into a seed. The stem of gymnosperms can be branched or unbranched. The thick cuticle, needle-like leaves, and sunken stomata reduce the rate of water loss in these plants.

The family of gymnosperms consist of conifers, the cycads, the gnetophytes and the species of Gynkgophyta division and Ginkgo biloba.

Let us have an overview of the characteristics, examples, classification and examples of gymnosperms.

Angiosperm

A plant of a large group that comprises those that have flowers and produce seeds enclosed within a carpel, including herbaceous plants, shrubs, grasses, and most trees. Compare with gymnosperm.

Alternation of generations:

• The diploid sporophyte has a structure called a sporangium.
• The sporangium undergoes meiosis and forms haploid spores.
• The spore develops into a gametophyte which is haploid in nature.
• The gametophyte has the reproductive organs which undergo mitosis to form haploid gametes.
• The gametes fertilize to form a haploid zygote which matures into a mature sporophyte. This cycle keeps repeating.

Monocot

In this type of angiosperms, only one cotyledon is present. Also, leaves are parallel-veined, and vascular bundles are scattered. The root system is adventitious. Examples: Wheat, Maize, Rice etc.

Dicot

There are two seed leaves present in dicot angiosperms. Vascular bundles are in a ring and veins are branched. Also, tap roots are present. Examples: Potato, Pea, Banyan etc.

Also check

• Animal Kingdom Notes for NEET Biology Chapter 4
• Morphology of Flowering Plants Notes for NEET Biology Chapter 5
• Plant Kingdom Notes for NEET Biology Chapter 3
• Biological Classification Notes for NEET Biology Chapter 2
• The Living World Notes for NEET Biology Chapter 1

Plant Kingdom: NEET Biology Chapter 3 Notes

This chapter is essential for understanding the diversity and classification of plants, including their structure, function, and reproduction. Our detailed notes are designed to simplify complex concepts, making them easier to understand and remember. These notes will serve as a valuable resource in your NEET preparation, helping you to master the key points efficiently.

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