The classification of the Plant Kingdom was made by R.H. Whittaker in 1969. According to that, the living organisms can be divided into five segments called ‘kingdoms’ such as Monera, Protista, Fungi, Plantae, and Animalia. They can also be divided based on characteristics such as their mode of nutrition, cellular and body composition, type of reproduction, etc.

• The chapter on the Plant Kingdom contains a weightage of 2 to 3% in NEET. 

• Expected Questions to be asked from this topic are 3 to 4 which will carry 12 to 16 marks in total. 

Most of the questions from this topic will demand a comprehensive view of the topic as well as its sub-topics. In addition to other topics, the topic of the Plant Kingdom is one of the most important topics to be covered for NEET. 

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Characteristics of the Plant Kingdom and its systems

• They are non-motile, living anchored to a substrate.

• The chief mode of nutrition for the plant kingdom is ‘photosynthesis’. However, several plants have also become absorptive.

• Plants carry photosynthetic pigment in plastids and chloroplast, which is a principal component for photosynthesis.

• Their mode of reproduction is usually asexual or sexual and they have multi-cellular reproductive organs.

• Plants are multi-cellular organisms having walled and frequently vacuolate eukaryotic cells.

The Plant Kingdom has been classified with the help of various systems of classifications. The major four systems have been mentioned below:

1. Artificial system- This classification is based on merely a few morphological features. It is the most primitive form of classification. E.g. Linnaeus is the classified plants which are based on the structure and number of stamens present;

2. Natural system- This system of classification relies on both morphological and anatomical features such as cellular ultrastructure, phytochemistry, embryology, etc. It relies on all the characteristics, hence is more feasible to use.

Examples of Natural system of classification may include Bentham and Hooker classification in which plants are divided on the basis of the presence and absence of flowers and seeds into Phanerogamia and Cryptogamia respectively;

3. Phylogenetic system- This system of classification finds its basis on the evolutionary and genetic relationship of plants, e.g. Whittaker, Engler and Prantl, Eichler, etc. It is based on several dissimilarities and similarities.

4. The traditional system of classification divides the plant kingdom into further two parts; cyptogamae and phenerogamae.

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Classification of Plant kingdom

CRYPTOGAMAE: The word has been derived from two Greek words ‘Kryptos’ and ‘gamos’, meaning concealed and marriage, respectively. Thus, the word ‘cryptogamae’ refers to hidden reproduction. These plants bear no flowers or fruits and include all the non-seed bearing plants.

PHANEROGAME: The word ‘Phanerogamae’ has a Greek root word called ‘faneros’ which means evident. Thus, Phanerogamae is the seed-bearing plant and is considered the most advanced plants.

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Quick Revision Notes on ALGAE

1. The plant body to which algae belongs is ‘Thallus’. The study of algae is known as Algology or Phucology.

2. Fritsch, who explained the structure and reproduction system of algae in 1935 is known as the Father of Algae.

3. Algae are simple, autotrophic avascular plants, having mostly aquatic habitat like marine or freshwater. They can also be found in moist soils, wet stones, and wood.

4. They have chlorophyll, a cellulose cell, and starch which makes them fall under the category of ‘plants’.

5. They possess uni-celled sex organs that do not have embryo formation.

6. Reproduction is done by all three kinds; i.e. by the vegetative, sexual, and asexual method. Vegetative reproduction in algae refers to reproduction by fragmentation. Asexual reproduction is done by the formation of spores like Akinetes (non-motile), Zoospores (motile), etc., whereas sexual reproduction takes place by fusion of gametes. 

7. Sexual reproduction can be further divided into three types: Isogamous, Anisogamous, and Oogmous.

8. The body or thallus of multicellular algae ranges from microscopic unicellular (Chlamydomonas), colonial (Volvox), aggregates of cells, fine filaments (Ulothrix), Acetabularia (largest unicellular algae), to Ectocarpus- filamentous branched and epiphytes (grow on other plants).

Some of the specialized habitats of algae are given below:

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Importance And Uses Of ALGAE:

• Algae play a major role in contributing to half of the total carbon dioxide fixation on the Earth.
• Algae have medicinal properties and also used to prepare antibiotics,
• They are important primary producers in the aquatic environment.
• Algae are used as fodder and in sewage treatment or pollutions control.
• Alginates like sodium laminarin sulphate and fucoidan are used as a blood anticoagulant.
• Laminaria, Sargassum, Ulya are used as food.
• Hydrocolloids are produced from brown and red algae, e.g. algin is produced by brown algae and carageen is produced by red algae.
• Agar (China grass) is widely used in laboratories as a growing medium for the tissue culture of microorganism and to prepare various desserts, jellies, and icecreams

Sample Question:

Ques; Which of the following statements is incorrect?

1. Agar-agar is obtained from Gelidium and Gracilaria.

2. Sargassum and Laminaria are used in food.

3. Algae is obtained from red algae and carrageenan from brown algae.

4. Algae increase the level of dissolved oxygen in the immediate environment.

Correct answer: (C).

Bryophytes and its types

Bryophytes non-vascular plants (lack xylem and phloem). They use water for sexual reproduction and are also known as ‘amphibians of the plant kingdom’. The main characteristics of Bryophytes include:

• Their plant body is not segmented into roots, stem, and leaves.
• They possess hairy like structures called ‘Rhizoids’.
• The presence of multi-cellular sex organs can be found in them.
• The plant body is thallus-like, prostrate, or erect.
• They provide food to birds and other animals.
• The main plant body of bryophyte is haploid in nature. This is known as gametophyte which produces gametes.
• Vegetative reproduction is by fragmentation, budding, tubers, gemmae, etc.
• The female sex organ is known as archegonium which is flask-shaped. It produces an egg.
• The male sex organ is known as antheridium which produces male gametes known as antherozoids.
• Sexual reproduction is by the fusion of male and female gametes (antherozoids and egg or oospore) in the sex organs, which are multicellular and jacketed.

The Bryophytes can be further divided into two parts:

• Liverworts- These are found in shady and moist places. In liverworts, asexual reproduction occurs with the help of fragmentation and specialized structures known as ‘Gemmae’.

• Mosses- These are flowerless plants and their life cycle includes two stages- ‘Protonema’ and ‘Leafy’ stage. ‘Protonema’ is formed from spores whereas the ‘Leafy stage’ gets developed from secondary protonema.

Sample Question

Ques. Spore dissemination in liverworts is aided by?

1. Calyptras.

2. Elators.

3. Peristome teeth.

4. Indusium.

Correct answer: (B).

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Pteridophytes and its characteristics

Pteridophytes are also known as ‘vascular cryptograms’ because they possess xylem and phloem. They are nicknamed as ‘botanical snakes’ as they evolved after bryophytes (botanical amphibians). The main characteristics of Pteridophytes are:

• Pteridophytes are found in cool and shady places mostly, but some can also flourish in well sandy-soil conditions.
• They are used for medicinal purposes and as soil-binders. They can also be grown on ornamentals.
• In pteridophytes, the main plant body, the sporophyte is segmented into true root, stem, and leaves.
• These types of plants include horsetails and ferns.
• Spores formed can be homosporous (spores of similar kind) or heterosporous (spores of different kinds). Homosporous spores are found in the majority of pteridophytes and spores found in Selaginella and Salvinia are heterosporous.
• The leaves in Pteridophyta are small (microphylls) as in Selaginella or large (macrophytes) as in ferns.
• The female sex organ is known as archegonium while male sex organ is known as antheridium.
• Water is required for the transfer of antherozoids to the mouth of the archegonium.

The pteridophytes can be further classified into four classes:

• Psilopsida (Psilotum)

• Lycopsida (Selaginella, Lycopodium)

• Sphenopsida (Equisetum)

• Pteropsida (Dryopteris, Pteris, Ferns, Adiantum)

Sample Question

Select the correct statement from the following:

1. The origin of seed habits can be traced in pteridophytes.

2. Water is not essential for fertilization in pteridophytes.

3. Antheridiophores and archegoniophores are present in pteridophytes.

4. Spores formed in pteridophytes are only homophonous.

Correct Answer: (A)

Gymnosperms and its classes

Gymnosperms are the seed-producing plants in which, however, the seeds are unenclosed by a seed coat. Some examples of gymnosperms can be Gnetophytes, Conifers, Cycads, etc. The main characteristic features of this plant kingdom are as follows:

• They are the seed-producing and non-flowering plants.

• Term gymnosperm was introduced by Theophrastus.

• Gymnosperms are more ancient than angiosperms

• They have a well-developed tap root system. Stems can be branched such as in the case of Pinus, but it can be un-branched such as in Cycas.

• Needle-like leaves are present Gymnosperms to reduce the surface area. For example, in Conifers.

• All gymnosperms are perennial and include medium-sized trees or tall trees and shrubs.

• Spores are heterosporous. Female spores are known as megaspores whereas male spores are known as microspores.

• Pollen tubes carry male gametes towards the archegonia. Then the fertilization occurs between the male gamete and female gamete. The zygote formed develops into an embryo and ovules develop into seeds.

Gymnosperms are classified into three classes:

• Cycadopsida (Cycas)

• Coniferopsida (Pinus, Ginkgo)

• Gnetopsida (Gnetum)

Sample Question

Ques. Which one of the following statements is correct?

5. Gymnosperms are both homosporous and heterosporous.

6. Ginkgo, Gnetophytes, Conifers are gymnosperms.

7. Needle-like leaves are present Gymnosperms to expand the surface area.

8. The leaves of gymnosperms are not well adapted to extremes of climate.

Correct Answer: (B)

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Angiosperms

Angiosperms are flowering plants in which the seeds are enclosed by fruits. They provide us with food, fodder, fuel, medicines, and several other commercially important products. The main characteristics include:

• In angiosperms, the pollen grains and ovules are developed in specialized structures called flowers.

• The male sex organ is the stamen. Stamen comprises of anther and the filament.

• The female sex organs in a flower is the pistil or the carpel.

• Pollen grains, after dispersal from the anthers, are carried by wind or various other agencies to the stigma of a pistil. This is termed as pollination.

• Reproduction happens through double fertilization.

They are divided into two parts:

1. Dicotyledonous plants; characterized by two cotyledons

2. Monocotyledonous plants- characterized by only one cotyledon.

Sample Question

Ques. Who among the following exhibit ‘Double fertilization’?

a. Algae

b. Gymnosperms

c. Angiosperms

d. Fungi

Correct Answer: (C)

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Sample Questions from previous years’ papers:

Ques-1 Choose the incorrect statement from the options given below.

1. Algae can be classified as per their pigments.

2. All algae are filamentous.

3. Spirogyra does not produce zoospores.

4. Most algae are photosynthetic.

Answer- (B)

Ques-2 Choose the statement which can be considered as the best evidence to show that two species of algae are closely related.

1. They both are in the same habitat.

2. They both reproduce asexually.

3. They both respire and release Carbon Dioxide.

4. They both have same type of pigments.

Answer- (D)

Ques-3 In which of the following, ‘Taproots’ are most commonly found?

1. Dicots

2. Angiosperms

3. Gymnosperms

4. Monocots

Answer- (A)

Ques-4 What differentiates an Angiosperm from a Gymnosperm?

1. Seed

2. Xylem Tracheids

3. Ovule

4. Xylem vessels

Answer- (D)

Ques-5 Which of the following is a plant that has vascular supply and produces spores but lack seeds?

1. Angiosperm

2. Bryophyte

3. Pteridophyte

4. Gymnosperm

Answer- (c)

Ques-6 Which of the following differentiates Bryophytes from Pteridophytes?

1. An independent gametophyte

2. Lack of vascular tissue

3. Swimming antherozoids

4. Archegoina

Answer- (B)

Ques-7 Choose the correct option- “Endosperm in gymnosperms is formed before fertilization and is always_______”?

1. Haploid

2. Diploid

3. Polypoid

4. Triploid

Answer- (A)

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Some Tips to Solve Questions

1. Stay calm and positive: It is important to keep a steady head and stay positive while writing the exam. Do not panic, take a deep breath, and start solving the paper.

2. Attempt the questions wisely: If you think you know the answers to some questions than others, attempt those questions first. Leave the difficult questions for a later time. This will help in boosting your confidence to attempt questions.

3. Take note of negative marking: Since the NEET exam contains the provision of negative marking for incorrect answers, you must attempt the question rationally. If you are very doubtful for the answers to some questions, straightaway leaves them, than just guessing irrationally. No marking is better than negative marking.

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How to prepare for NEET Biology section?

Biology section in NEET 2021 carries most of the marks – 90 marks, with 45 for Botany and 45 for Zoology. This means that the number of questions that are asked in this section will be more than in other sections. The plant kingdom is one of the most important sections of Botany. Thus, to have a good command over this section, students must read and understand the concepts comprehensively. In order to prepare for this section, the following tips can be helpful:

• Read thoroughly: Reading the concepts and understanding the basics thoroughly is the key to solve many questions. Do not cram up the concepts, but make an idealized plan to learn and understand the key areas.

• Make things easy to learn: Since there are a lot of terms in biology which are difficult to remember, you can make flowcharts, flashcards, paper flags, tables, and use highlighters, to learn them.

• Practice by solving previous years’ papers: Solving sample papers and previous years’ question papers can be largely helpful in gaining a command over the subject as well as getting to know the types of questions that are usually asked in the exam. This practice will also help you in understanding the basic pattern of the exam.

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