RBSE Solutions Class 11 Biology Chapter 23 Plant Taxonomy

RBSE Class 11 Biology Chapter 23 Multiple Choice Objective Questions

Question 1. What is the smallest unit of plant taxonomy?
(a) Intra specific group
(b) Species
(c) Genus
(d) Family
Answer: (b) Species
In simple words: The basic building block in how we classify plants is called a species. It represents a group of very similar plants.

🎯 Exam Tip: Remember the hierarchy of taxonomic ranks: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. Species is the most specific unit.

Question 2. Who is the father of taxonomy?
(a) Takhtajan
(b) Linneus
(c) Bentham and Hooker
(d) Theophrastus
Answer: (b) Linneus
In simple words: Carl Linnaeus is known as the father of taxonomy because he created the system we use today to name and classify living things. He gave each plant and animal two names.

🎯 Exam Tip: Knowing the key scientists associated with foundational concepts like taxonomy is important for multiple-choice questions.

Question 4. Who proposed natural system of classification of plants?
(a) Hutchinson
(b) Engler and Prantl
(c) Bentham and Hooker
(d) John Ray
Answer: (c) Bentham and Hooker
In simple words: Bentham and Hooker developed a natural way to classify plants. Their system grouped plants based on many shared natural features, not just a few.

🎯 Exam Tip: Differentiate between artificial, natural, and phylogenetic systems of classification and the scientists associated with each.

Question 5. Which botanical name is correct?
(a) Pisum Sativum
(b) Pisum sativum
(c) Pisum sativum
(d) pisum Sativum
Answer: (c) Pisum sativum
In simple words: The correct way to write a scientific plant name is to capitalize the first letter of the genus name (Pisum) and keep the species name in lowercase (sativum). Both names should also be italicized.

🎯 Exam Tip: Always remember the rules of binomial nomenclature: the genus name starts with a capital letter, the species name starts with a small letter, and both are italicized when typed or underlined when handwritten.

RBSE Class 11 Biology Chapter 23 Very Short Answer Questions

Question 1. What do you mean by phylogenetic?
Answer: Phylogenetic classification is a way to group organisms that shows their evolutionary and genetic relationships. It traces how different species have changed and developed over time from their first origin until now. This helps us understand the family tree of life.
In simple words: Phylogenetic means classifying living things based on their family history and how they evolved.

🎯 Exam Tip: Focus on "evolutionary" and "genetic relationships" as keywords when defining phylogenetic classification.

Question 3. What is full form of ICBN?
Answer: The full form of ICBN is "International Code of Botanical Nomenclature". This code sets the rules for naming plants. These rules ensure that each plant has a unique scientific name worldwide.
In simple words: ICBN stands for International Code of Botanical Nomenclature, which is a set of rules for naming plants.

🎯 Exam Tip: Full forms of abbreviations are common in biology, so memorize them carefully. ICBN ensures uniform plant naming globally.

Question 4. Define taxonomy?
Answer: According to G.H.M. Lawrence (1951), plant taxonomy is a part of science that focuses on identifying, naming (nomenclature), and classifying plants. It helps us organize the vast diversity of plant life. Taxonomy provides a universal system for recognizing and grouping plants.
In simple words: Taxonomy is the science of finding, naming, and grouping plants.

🎯 Exam Tip: When defining taxonomy, ensure you include the three key processes: identification, nomenclature, and classification.

Question 5. Which two names are considered for writing botanical name of a plant?
Answer: When writing the botanical name of a plant, two names are considered: the first name is the generic name (Genus), and the second name is the specific name (Species). This two-part naming system, called binomial nomenclature, helps to uniquely identify each plant. For example, in *Mangifera indica*, 'Mangifera' is the generic name and 'indica' is the specific name.
In simple words: For a plant's scientific name, we use two parts: the genus name first, then the species name.

🎯 Exam Tip: Always remember that botanical names follow binomial nomenclature, consisting of a generic name and a specific epithet.

Question 6. Which language is used to write botanical names of plants?
Answer: Latin is the language used to write the botanical names of plants. Latin is a "dead language," meaning it doesn't change over time, ensuring that scientific names remain stable and universally understood. This consistency helps scientists worldwide communicate clearly about different plant species.
In simple words: Plant scientific names are always written in Latin.

🎯 Exam Tip: Latin is chosen for scientific names because it is a stable language, preventing changes in meaning over time.

Question 7. Which word represent genus in Cassia fistula?.
Answer: In the botanical name *Cassia fistula*, the word that represents the genus is "Cassia". The generic name always comes first in a scientific name. This name groups together closely related species. So, *Cassia* is the genus for this particular plant.
In simple words: In the name *Cassia fistula*, 'Cassia' is the genus.

🎯 Exam Tip: The first part of a binomial name always indicates the genus, and it is capitalized.

Question 8. Who proposed concept of species?
Answer: John Ray proposed the concept of species. He was one of the first to give a clear definition of what a species is, helping to lay the groundwork for modern taxonomy. His work provided a foundational understanding of distinct groups of organisms. He described how organisms of the same species can reproduce to make more of their kind.
In simple words: John Ray was the first to properly define what a "species" is.

🎯 Exam Tip: Associate John Ray with the early concept and definition of "species" in biological classification.

Question 9. Which type of classification used in Indian Universities and Herberium to identify and classified plants?
Answer: Indian Universities and Herbaria primarily use the natural system of classification, especially the one proposed by Bentham and Hooker, to identify and classify plants. This system groups plants based on a large number of natural characteristics, showing their true relationships. The system focuses on observable morphological features. It is still widely followed for practical identification.
In simple words: Indian universities and plant collections mostly use the natural classification system, like the one by Bentham and Hooker, for plants.

🎯 Exam Tip: Remember that the Bentham and Hooker system, a natural classification, is popular in many herbaria for its practical utility.

RBSE Class 11 Biology Chapter 23 Short Answer Questions

Question 1. Define species.
Answer: A species is a group of individual plants that are very similar in their physical appearance (morphology) and genetic makeup. They can freely interbreed with each other in nature, meaning they can reproduce to create fertile offspring. This ability to interbreed helps them maintain their group over generations. This distinct group is the basic unit of classification.
In simple words: A species is a group of similar plants that can naturally reproduce with each other.

🎯 Exam Tip: The key elements for defining a species are morphological and genetic similarity, and the ability to interbreed freely in nature to produce fertile offspring.

Question 2. Explain natural and Phylogenetic Classification.
Answer:
Natural Systems:
• A natural system of classification groups organisms based on many near-permanent shared characteristics that show their true relationships. This system considers various features to find natural affinities among living things.
• This type of plant classification looks at many natural similarities in their structure, including various physical traits of the plant. It tries to reflect actual biological relationships.
Phylogenetic Systems:
• A phylogenetic system of classification shows the evolutionary and genetic relationships among organisms. It tracks how organisms have evolved from their origin to the present day. This method helps us understand the evolutionary history of species. It is based on the idea that species change over time.
In simple words: Natural classification groups organisms by many real similarities, while phylogenetic classification groups them by their evolutionary history.

🎯 Exam Tip: For natural classification, think "overall similarities," and for phylogenetic classification, think "evolutionary relationships and common ancestry."

Question 3. Define Binomial Nomenclature.
Answer: Plant Binomial Nomenclature is a system that gives unique and correct scientific names to organisms. Each scientific name consists of two words: the first is the generic name (genus), and the second is the species name. For example, *Homo sapiens* refers to humans. This system helps scientists worldwide use the same name for each organism, avoiding confusion from common names. It ensures global consistency.
In simple words: Binomial nomenclature is a system where every plant gets a two-part scientific name: a genus name and a species name.

🎯 Exam Tip: Emphasize the two-word structure (genus + species) and the purpose of providing distinct, proper, and universally accepted scientific names.

Question 4. What do you understand by Artificial System of Classification?
Answer: An Artificial System of Classification groups organisms based on comparing only one or a few easily seen traits. These traits are chosen simply because they are convenient for the taxonomist. However, this type of classification is incomplete and not enough to fully understand where plants fit in a broader classification. For example, plants might be grouped by height or color, which doesn't reflect true relationships. This often leads to unrelated organisms being grouped together.
In simple words: Artificial classification sorts plants using only a few easy-to-see features, which doesn't show their real relationships.

🎯 Exam Tip: Highlight that artificial systems rely on a limited number of "superficial traits" and are often driven by convenience rather than true biological relationships.

Dicotyledons Characteristics (implied from context)

• Two cotyledons are present in the seed along with an embryo.
• They have an open and ring-type arrangement of vascular bundles.
• Their leaves show reticulate (net-like) venation.
• Flowers are typically pentamerous (parts in fives) or tetramerous (parts in fours).
In simple words: Dicotyledons have two seed leaves, net-like veins in their leaves, and flower parts usually in groups of four or five.

🎯 Exam Tip: When describing plant groups, always list key distinguishing features related to seed structure, leaf venation, vascular bundles, and floral symmetry.

Class II: Monocotyledonae

• This group includes angiosperms (flowering plants) where the seed has only one cotyledon (seed leaf).
• Their leaves are simple and show parallel venation (veins run parallel to each other).
• They have a closed type of vascular bundles because cambium (tissue for secondary growth) is absent. The vascular bundles are scattered in the parenchyma (ground tissue).
• Flowers usually have parts in threes (trimerous). Their roots are adventitious, meaning they grow from parts other than the main root.
• This class is further divided into seven series.
In simple words: Monocots have one seed leaf, parallel veins in their leaves, scattered vascular bundles, and flower parts in threes.

🎯 Exam Tip: Key features of monocotyledons include a single cotyledon, parallel venation, adventitious roots, and trimerous flowers.

Class III: Gymnospermae

• Gymnosperms are placed between the Dicotyledons and Monocotyledons classes in some classification systems.
• Their reproductive structures are in the form of male and female cones, rather than flowers.
• In this group, the ovule or seed is naked, meaning there is no ovary or fruit enclosing it. This is a distinguishing feature.
In simple words: Gymnosperms are plants with naked seeds, found between dicots and monocots, and reproduce using cones.

🎯 Exam Tip: The defining characteristic of Gymnospermae is the presence of "naked seeds" (not enclosed within a fruit).

Question 6. Define Systematic.
Answer: Systematic (from "Systema," meaning a whole made of parts) is the science that reveals the unique properties at each level of grouping organisms. It involves identifying, naming (nomenclature), describing, and classifying organisms based on the distinct characteristics of every species and group of species at each classification level. It provides a comprehensive framework for understanding biodiversity. This field aims to understand the relationships among organisms.
In simple words: Systematic is the science that studies how organisms are identified, named, described, and classified based on their unique traits and relationships.

🎯 Exam Tip: When defining systematics, ensure you include identification, nomenclature, description, and classification, focusing on the unique properties and relationships at each level.

Question 7. How Cruciferae family defined and explained in ancient text ‘Vrikshayurveda'?
Answer: In the ancient text ‘Vrikshayurveda’, the Cruciferae family was explained by categorizing its members as trees, shrubs, and herbs, and by describing their various uses. This shows an early understanding of plant classification based on growth form and practical utility. The text highlights traditional knowledge about plants. This ancient system aimed to simplify plant study.
In simple words: The ancient text 'Vrikshayurveda' described the Cruciferae family by classifying them as trees, shrubs, or herbs and explaining what they were used for.

🎯 Exam Tip: For historical context, remember that ancient texts often classified plants based on observable features like growth habit (trees, shrubs, herbs) and practical uses.

RBSE Class 11 Biology Chapter 23 Essay Type Questions

Question 1. Explain Bentham and Hooker's classification up to class level. Write its lay out, important characters. Write its merit and demerits.
Answer:
Bentham and Hooker's System of Classification:
• George Bentham, a self-trained British botanist, and Sir Joseph Dalton Hooker, Director of the Royal Botanic Gardens, Kew (England), proposed a natural system of classification. They published this in their three-volume book, "Genera Plantarum." This book describes all known genera of seed plants in Latin.

• The first volume of their book was released in 1862, and the final volume in 1883.
• This classification system is widely regarded as one of the best and most accepted natural systems. It is still used in many herbaria globally, including those in India. It is derived from the systems of de Jussieu and de Candolle.
• De Candolle had grouped Gymnosperms with Dicotyledons. However, Bentham and Hooker separated all seed plants (Phanerogames) into Dicotyledons, Gymnosperms, and Monocotyledons. They placed Ranales at the beginning of the classification and grasses at the end. Their system placed Gymnosperms between Dicotyledons and Monocotyledons.
• Bentham and Hooker classified seed plants (Phanerogames) into three main classes. They based this on many morphological features like leaf arrangement (phyllotaxy), vein patterns (venation), flower parts (calyx, corolla, androecium, gynoecium), seed coat, and the number of cotyledons in plants. The three classes identified were Dicotyledons, Gymnosperm, and Monocotyledons. These scientists greatly influenced botany.

De-Merits of Bentham and Hooker's System:
1. This system does not offer any insight into the evolutionary history of any genus, family, or order, meaning it is not phylogenetic.
2. The classification primarily relies on single and artificial characters. As a result, closely related families are sometimes placed far apart from each other.
3. The grouping called "Monochlamydeae" is considered entirely artificial, meaning it does not reflect natural relationships.
4. Gymnospermae is positioned between the Dicotyledons and Monocotyledons, which is seen as very unusual and not natural.
5. Advanced families like Orchidaceae and Scitamineae are placed at the beginning of the monocots, which is not ideal.
6. Liliaceae and Amaryllidaceae, despite being very closely related, are kept separate in this system.
7. The Amaryllidaceae family is more closely related to Liliaceae. However, it is grouped with Scitamineae in the series Epigynae, due to having an inferior gynoecium.
8. The placement of the series Apocarpae is considered unsatisfactory due to its free and superior carpels.
In simple words: Bentham and Hooker created a natural plant classification based on many physical traits, dividing seed plants into Dicotyledons, Gymnosperms, and Monocotyledons. While widely used, its drawbacks include not showing evolutionary history and sometimes separating closely related plant groups.

🎯 Exam Tip: For essay questions on classification systems, structure your answer to include the proponents, key features, layout (if applicable), and clear points for both merits and demerits.

Question 3. Explain concept of Genus and species with examples.
Answer:
Concepts of Species:
• The first logical and scientific concept of species was given by Carolus Linnaeus in 1753. This formed the basis of modern classification. He established a clear framework for defining distinct groups.

Some Popular Definitions of Species:
• The term 'species' was first used by John Ray. His work helped to standardize the naming of different life forms.
• A species is a group of individual plants that are identical in their physical appearance and other characteristics. They can freely interbreed and reproduce sexually among themselves to produce new offspring, ensuring the continuation of their life.
• However, individuals of one species cannot interbreed or reproduce sexually with individuals of another species. This is because the exchange of genetic material is not possible between them.
• In simple terms, a species is a group of individual plants that are morphologically and genetically similar and can freely interbreed in nature to maintain the continuity of life. Intra-specific categories (groups within a species) show uniformity in external and internal characters. However, it's observed that intra-specific categories might differ genetically and physically.

The Concept of the Genus:
• The word "genus" was coined by John Ray, same as "species."
• Genus is the first higher taxonomic category, meaning it's above the species level. It groups together several species that are closely related.
• A genus is formed by a group of species that share more similar characteristics with each other than with species from other genera. This level shows broader relationships.

a. **Monotypic genus:** A genus that contains only one species is called a monotypic genus. For example, the genus *Homo* is monotypic because it contains only one species, *Homo sapiens*.
b. **Polytypic genus:** A genus that contains two or more species is called a polytypic genus. For example, the genus *Panthera* is polytypic, including species like *P. leo* (lion), *P. tigris* (tiger), *P. onca* (jaguar), and *P. pardus* (leopard).

• The concept of genus is very old, with different plant genera mentioned in ancient Hindi and Sanskrit texts, such as Pine, Basil, and Oak.
• All species of Pine are grouped under the genus *Pinus*. All species of Basil are under the genus *Ocimum*, and all species of Oak are under *Quercus*.
• The use of Latin names in plant nomenclature was started by Tournefort (1700), who described about 700 genera in his book "Institutiones rei herbaria."
In simple words: A species is a group of similar organisms that can reproduce together, like all types of peas. A genus is a broader group that includes several similar species, like different types of cats (lions, tigers, leopards) all in the genus Panthera.

🎯 Exam Tip: Clearly define species by emphasizing interbreeding ability and morphological similarity. For genus, focus on it being a group of related species. Provide clear examples for both monotypic and polytypic genera.

Question 4. Explain various types of classification and its basis with suitable examples.
Answer:
Types of Plant Classification
We know there are over 400,000 species of plants, with more than half being angiosperms (flowering plants). Angiosperms are found almost everywhere on Earth, from dense forests and deserts to hills, mountains, and even deep oceans. Since the time of Theophrastus (370-285 BC), many scientists have studied plants for their naming, classification, and identification. All types of classifications can be put into three main categories:

All types of classifications can be grouped into these three categories:

1. Artificial Systems:
• This system of classification is based on comparing one or a few easily noticeable traits, like color or height. It is a very basic way to organize plants. This often leads to plants with very different underlying biology being grouped together.
• The traits used for classification are chosen mostly for the convenience of the taxonomist, not necessarily because they show deep biological relationships.
• This type of classification is incomplete and not detailed enough to fully understand the classification position of plants. It doesn't give a full picture of their relationships.
• Theophrastus first used artificial classification, grouping plants into four categories: (a) Herbs, (b) Undershrubs, (c) Shrubs, and (d) Trees.

Disadvantage of artificial systems:
• They use only one or a few traits for comparison, which can group different organisms together wrongly.
• The criteria chosen for grouping might be insignificant, such as whether a plant lives for one year (annual) or two years (biennial). These traits do not reflect true biological relationships. This limited focus makes them less accurate.

2. Natural Systems:
• A natural system of classification is based on comparing a large number of stable characteristics that reveal the natural relationships among organisms. This is considered a more scientific approach than artificial systems.
• This type of plant classification relies on the natural similarities in plant structures, meaning it considers various physical and morphological characteristics. It aims to show true biological affinities.
• The first natural classification of plants was proposed by Schimper (1879) and further developed by Eichler (1883). Their work helped establish a more robust system.
• Bentham and Hooker's classification is an excellent example of a natural classification. They detailed it in their book 'Genera Plantarum'.
• A.P.D. Candolle, John Lindley, and de Jussieu are other famous scientists known for their contributions to natural classification. These systems gained widespread acceptance because they reflected real biological connections.
• Natural systems were dominant before the concept of evolution was fully accepted in systematics. They provided a strong foundation for understanding plant relationships.

3. Phylogenetic Systems:
• The concept of phylogenetic classification emerged after Charles Darwin's theory of "Origin of Species by Natural Selection." It changed how scientists thought about relationships between organisms.
• This system of classification shows the evolutionary and genetic relationships among organisms, tracing them from their origin to the present day. It aims to create a family tree of life.
• The study of a species from its origin to the present time is called phylogeny. It helps us understand how species have changed over eons.
• In this type of classification, angiosperms are categorized into families based on their evolutionary history (phylogeny). This reflects how they developed over time.
• Scientists like Engler and Prantl (1887-1889), Hutchinson (1926, 1934), Takhtajan (1954), Cronquist (1968), Dahlgren (1975), and Thorne (1981) are well-known for their phylogenetic classifications. Their work forms the backbone of modern evolutionary biology.
In simple words: Plant classification can be artificial (based on a few obvious traits), natural (based on many real similarities), or phylogenetic (based on evolutionary history). Each type helps us organize plants in different ways.

🎯 Exam Tip: Clearly distinguish the basis (superficial, overall natural affinities, evolutionary history) and give examples for each classification type. A simple diagram can enhance your answer.

RBSE Class 11 Biology Chapter 23 Additional Questions

Question 2. What is name of book wrote by A.P. de Candolle?
Answer: The name of the book written by A.P. de Candolle is "Theory of Elementary Botany." This book was a significant contribution to the field of botany, helping to establish principles of plant classification and nomenclature. It laid important groundwork for future botanical studies.
In simple words: A.P. de Candolle wrote a book called 'Theory of Elementary Botany'.

🎯 Exam Tip: Remember key works by influential scientists, as they often mark important advancements in the field.

Question 3. Who is known as father of botany?
Answer: Theophrastus is known as the "father of botany." He was a student of Aristotle and wrote extensively about plants, classifying them based on their forms and uses. His writings, particularly "Enquiry into Plants" and "On the Causes of Plants," are considered the earliest systematic botanical works. He laid the foundation for the scientific study of plants.
In simple words: Theophrastus is called the father of botany because he was the first to seriously study and write about plants.

🎯 Exam Tip: Theophrastus is a foundational figure in botany due to his early systematic descriptions and classifications of plants.

Question 4. Name the book in which Bentham and Hooker gave their classification.
Answer: Bentham and Hooker presented their classification system in a book called "Genera Plantarum." This three-volume work details their comprehensive natural system of plant classification. It is a highly respected and widely used reference in botany. This book provided a detailed and practical guide for plant identification.
In simple words: Bentham and Hooker wrote their plant classification in a book called 'Genera Plantarum'.

🎯 Exam Tip: It is crucial to associate the "Genera Plantarum" with Bentham and Hooker's natural system of classification.

Question 5. Define Polypetalae.
Answer: Polypetalae is a subclass of dicotyledons where the flowers have both a calyx (sepals) and a corolla (petals), and importantly, the petals of the corolla are free, meaning they are not fused together. This distinct characteristic helps in identifying plants within this group. This arrangement of petals is a key morphological feature for classification. The term "poly-" means many, and "petalae" refers to petals.
In simple words: Polypetalae describes a group of dicotyledons where the flower petals are separate and not joined together.

🎯 Exam Tip: The defining characteristic of Polypetalae is the presence of free (unfused) petals in the flower.

Question 6. What are the demerits of Bentham and Hooker's classification?
Answer:
De-Merits of Bentham and Hooker's System:
1. The system does not give any information about the evolutionary history of any genus, family, or order. This means it is not phylogenetic and does not reflect how species evolved.
2. In this system, plants are grouped mainly based on a few single and artificial characters. As a result, closely related families can be placed far apart from each other, which is not ideal for understanding true relationships.
3. The group "Monochlamydeae" is entirely artificial. It does not represent a natural grouping of plants. Its creation was for convenience, not biological accuracy.
4. Gymnospermae is positioned between the Dicotyledons and Monocotyledons, which is considered very unusual and anomalous. This placement does not align with evolutionary understanding.
5. Advanced families, such as Orchidaceae and Scitamineae, are treated as if they are less evolved by being placed at the beginning of the monocots. This contradicts modern understanding of plant evolution.
6. Liliaceae and Amaryllidaceae, which are very closely related families, are kept separate in this classification system. This separation does not reflect their close biological ties.
7. The Amaryllidaceae family is more closely related to Liliaceae. However, in this system, it is grouped with Scitamineae in the series Epigynae because of its inferior gynoecium. This grouping overlooks stronger relationships.
8. The position of the series Apocarpae is considered unsatisfactory. This is due to its flowers having free and superior carpels, which caused issues in its classification. This placement has been a point of criticism.
In simple words: Bentham and Hooker's classification has flaws: it doesn't show evolution, sometimes separates similar plants, and places some advanced groups incorrectly.

🎯 Exam Tip: When listing demerits, focus on inconsistencies with evolutionary principles, reliance on artificial characters, and illogical placements of certain plant groups or families.