NCERT Class 11 Biology Chapter 1 Notes - The Living World PDF Notes

CBSE Quick Revision Notes Class 11 Biology Chapter 1: The chapter introduces students to the fundamental characteristics of living organisms, classification systems and the importance of nomenclature. It helps to understand how living beings differ from nonliving things and how they are scientifically classified. It also focuses on biodiversity, taxonomy and systematics. The Living World NCERT Notes for Class 11 Biology help you revise important concepts given in the NCERT Book in no time during the Board exam preparation. CBSE Class 11 Living World Notes will help you with quick revision.

This Story also Contains

1. NCERT Class 11 Chapter 1 Class Notes- The Living World
2. What is Living?
3. Diversity in the Living World
4. Binomial Nomenclature
5. Taxonomic Categories
6. Benefits of NCERT Class 11 Notes Chapter 1
7. Tips to learn NCERT Class 11 Biology Chapter 1 Notes

These notes provide a structured way to understand key concepts effectively. By studying this chapter, students gain knowledge of the scientific naming of taxonomic categories and the role of taxonomists in organising biological diversity. NCERT Solutions and the revision notes together are handy and beneficial to save you time. Students must go through each topic of the chapter as easily and effectively as possible with the help of NCERT Notes for Class 11.

Also, students can refer to:

• NCERT Solutions for Class 11 Biology Chapter 1 Living World

• NCERT Exemplar Class 11 Biology Chapter 1 Solutions Living World

NCERT Class 11 Chapter 1 Class Notes- The Living World

The summarised notes are given below-

What is Living?

The term "living" refers to the organisms that exhibit specific characteristics that set them apart from nonliving things. The fundamental characteristics of life include growth, reproduction, metabolism, and response to stimuli. Growth occurs through an increase in size and the number of cells as seen in both unicellular and multicellular organisms. Reproduction ensures the continuation of species and can be either sexual or asexual reproduction. Sexual reproduction helps in bringing variation in the species whereas Asexual reproduction only helps in the multiplication of the species. Metabolism involves all chemical reactions taking place within an organism that are essential for sustaining life. Responsiveness is the ability of an organism to sense and respond to environmental changes, which is a trait exclusive to only living beings.

All these properties of living beings are not individually created at the molecular level; rather they develop as a result of interactions among different molecules that constitute the cells and their organelles. Thus, we can define a living being as an interactive system that replicates, evolves and regulates itself and can respond to external stimuli.

Diversity in the Living World

The word biodiversity was first used by W. Rosen in 1985. Life on Earth is incredibly diverse, with millions of species inhabiting it. Biodiversity refers to the vast variety of living organisms, including plants, animals and microorganisms. Scientists estimate that over 1.7 million species have been identified, but many more remain undiscovered. This diversity is the result of evolution, which allows organisms to adapt to different environmental conditions. The study of diversity is important for conservation efforts and understanding the ecological balance. By classifying the organisms, biologists organise and study them systematically, making it easier to analyse their characteristics, evolutionary history and ecological roles.

Binomial Nomenclature

Binomial nomenclature is the scientific system of naming organisms using two Latinized dreams introduced by Carl Linnaeus. The first part represents the genus, and the second part denotes the species. For example, humans are scientifically called Homo sapiens, whereas homo is the genus and sapiens is the species. This system provides a universal naming convention, avoiding confusion caused by local or common. Binomial Nomenclature is governed by international codes such as the International Code of Botanical Nomenclature (ICBN) and the International Code of Zoological Nomenclature (ICZN), ensuring consistency and standardisation in naming living organisms.

Taxonomic Categories

Taxonomic categories refer to the hierarchical system of classification used to organise and categorise living organisms based on their characteristics. The classification system follows a structured sequence, with each category representing a specific rank. The system was formalised by Carolus Linnaeus and is universally accepted for the classification of organisms. The taxonomic hierarchy consists of seven major categories arranged from the broadest to the most specific:

Kingdom

The kingdom is the highest and most inclusive tax economic category. It groups organisms with the most fundamental similarities. Initially, Linneaus classified all living organisms into two kingdoms: Plantae, which included plants, and Animalia, which included animals. However, with advancements in microbiology and evolutionary studies, the classification expanded to five kingdom systems proposed by RH Whittaker in 1969. The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia. In modern taxonomy, a six-kingdom system is also used where Monera is divided into Archaebacteria and Eubacteria due to significant genetic differences.

Division or Phylum

Phylum (in animals) or Division (in plants) is the next level of classification in which organisms are grouped based on major structural and functional similarities. Organisms within a phylum share broad characteristics but may have distinct differences at lower levels.

Example: Phylum Chordata, which includes vertebrates like fish, amphibians, reptiles, birds, and mammals. Division Angiosperms that includes flowering plants in the Plant Kingdom.

Class

The class is a more specific taxonomic rank than Phylum or Division. It groups organisms within a phylum that share additional similarities. For instance, in the phylum Chordata, organisms are further divided into different classes, such as:

Class Mammalia, which includes mammals like humans, cats, and elephants. Class Aves, which includes birds like eagles and parrots. Class Reptilia that includes reptiles like snakes.

Order

The order is a taxonomic category that groups related families together. It reflects more precise similarities between organisms. For example, within the class Mammalia:

Order Carnivora includes families like Felidae and Canidae, and Order Primata include families such as Hominidae, which includes great apes and humans.

Family

A family consist of related genera that share a significant number of characteristics. It is a more specific level of classification than order. Organisms in the same family have many structural and genetic similarities.

Example: Family Felidae includes genera like Panthera and Felis (cats). Family Canidae includes genera like Canis (dogs)

Genus

The genus is one of the most crucial taxonomic categories. It consists of closely related species that share common characteristics but may differ in minor ways. The genus name is always written in italics with the first letter capitalised.

Examples are Homo (including Homo sapiens- humans)

Species

Species is the most specific fundamental taxonomic category. Organisms belonging to the same species can interbreed and produce fertile offspring. It represents a distinct biological identity.

For example, Homo sapiens (humans), Felis catus (domestic cats), Panthera tigris (tigers)

Taxonomical Aids

Taxonomical aids are tools that help in the identification, classification and study of organisms. The various taxonomical aids are:

Herbarium is a collection of dried and pressed plant specimens that are mounted on sheets and used for reference and botanical study purposes. It gives us knowledge and information regarding the flora of a specific location. It also gives information and general features of the species. It also helps in the identification of species and the classification of new species. It provides research and job facilities to taxonomists.

Botanical Gardens are institutions where plants are grown and maintained for research, conservation and educational purposes. It helps in the conservation of endangered and threatened plant species. The ex-situ conservation of many plant species is done. Most of the botanical garden serves as a herbarium depository. It provides materials for the study of biosystematics. Examples are the Royal Botanical Garden and the Indian botanical Garden zoo.

Zoological parks are the areas where animals are kept in a controlled environment for study, breeding and conservation. They serve as research centres for zoologists. They are important for the ex-situ conservation of wild animals. Breeding programmes are carried out in zoological parks. These are important recreation centres and are used for mass awareness of wild species. Important research tool for studying animal behaviour and life.

Museums store and preserve specimens of plants, animals and fossils, providing valuable historical and scientific information. They help in the preservation of collected plants and animal species. The collections are used for the taxonomic study of different taxa. They provide information regarding local flora and fauna.

A key is a system of contrasting statements is used to identify organisms based on their characteristics. These taxonomical aids are important for research, researchers, taxonomical students, and understanding and identifying diversity systematically.

Chapter-Wise NCERT Class 11 Notes Biology

The chapter-wise Notes for class 11 biology are given below:

Benefits of NCERT Class 11 Notes Chapter 1

• The notes help in building a fundamental understanding of life, its characteristics and classification systems.

• It covers essential topics that are frequently asked in board exams and entrance tests.

• It develops knowledge of taxonomic nomenclature and biodiversity conservation.

• It provides a base for all the entrance exams, such as NEET, AIIMS, and other medical exams.

• It helps to understand the importance of biodiversity, conservation, and environmental balance.

Subject Wise NCERT Exemplar Solutions

• NCERT Exemplar Class 11 Solutions
• NCERT Exemplar Class 11 Maths
• NCERT Exemplar Class 11 Physics
• NCERT Exemplar Class 11 Chemistry
• NCERT Exemplar Class 11 Biology

Tips to learn NCERT Class 11 Biology Chapter 1 Notes

• Use of mnemonics and memory tricks to remember taxonomic categories. For example, King Philip Came Over For Good Soup for the Kingdom, Phylum, Class, Order, Family, Genus, and Species.
• Flashcards can be made to write the taxonomic categories and examples to retain the information more effectively.
• Diagrams and flowcharts will be useful for classification, hierarchy and binomial nomenclature.
• Solving the previous year's questions and different MCQs will test the knowledge and improve exam readiness.

Subject Wise NCERT Solutions

• NCERT Solutions for Class 11 Mathematics
• NCERT Solutions for Class 11 Chemistry
• NCERT Solutions for Class 11 Physics

• NCERT Solutions for Class 11 Biology

The Chapter 1 notes will lay the foundation for understanding life and its classification. It introduces the students to fundamental biological concepts such as characteristics of living organisms, biodiversity and scientific nomenclature. By systematically studying classification and taxonomical aids, students will understand how scientists organise and study the diversity of life on Earth. Mastering this chapter will help students in board exams as well as for future studies and biology, especially for competitive exams like NEET.

Following are the links to the class 11 notes PDF download for all subjects:

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