The Living World
Welcome to HSLC Guru. This article presents complete English-medium notes and question answers for Class 11 Biology Chapter 1 — The Living World, prepared strictly according to the latest ASSEB (Assam State School Education Board) syllabus. Students will find a clear summary, short and long answer questions, MCQs, fill-in-the-blanks, true or false statements, and a glossary table to make exam preparation simple and effective.
Summary
The living world is incredibly diverse, comprising millions of species of plants, animals, microorganisms, and fungi. Despite this diversity, all living organisms share certain defining characteristics that distinguish them from non-living matter. The most important features of life are growth, reproduction, metabolism, cellular organisation, consciousness, and the ability to respond to environmental stimuli. Growth in living beings occurs from inside through cell division, while reproduction ensures continuity of species. Metabolism, the sum total of all chemical reactions in the body, is a defining feature found exclusively in living systems. Cellular organisation forms the basic structural and functional unit of all organisms.
Living organisms are also capable of maintaining homeostasis, which means keeping their internal environment relatively constant despite external changes. They show response to stimuli such as light, temperature, water, sound, and chemicals. Consciousness, the ability to sense surroundings and react accordingly, is considered the most defining property of living beings. The enormous variety of living organisms is referred to as biodiversity. To study such large numbers of organisms, scientists developed the science of classification, known as taxonomy, while systematics deals with classification along with evolutionary relationships.
Carolus Linnaeus, the father of modern taxonomy, introduced binomial nomenclature, a universal system of giving each organism a scientific name made of two parts — the genus name and the species name. For example, mango is named Mangifera indica. The names are written in Latin and follow internationally accepted rules. Taxonomic categories arrange organisms into a hierarchy: Kingdom, Phylum (or Division for plants), Class, Order, Family, Genus, and Species. Species is the lowest and most basic unit of classification, while Kingdom is the highest.
Several taxonomic aids have been developed to help in the identification, naming, and classification of organisms. These include herbarium (a collection of pressed and dried plant specimens), botanical gardens (live collections of plants), museums (preserved specimens of plants and animals), zoological parks (live animal collections), keys (analytical tools using contrasting characters), flora (books containing descriptions of plants of a region), manuals (information for identification), and monographs (detailed information on a single taxon). Together, these tools help students, researchers, and ecologists understand the rich biodiversity of our planet.
Very Short Answer Questions (1 Mark)
Q1. Who is known as the father of taxonomy?
Answer: Carolus Linnaeus is known as the father of taxonomy.
Q2. What is the scientific name of mango?
Answer: The scientific name of mango is Mangifera indica.
Q3. Define species.
Answer: A species is a group of individuals with similar features that can interbreed and produce fertile offspring.
Q4. What is biodiversity?
Answer: Biodiversity is the variety and variability of living organisms found on Earth.
Q5. What is binomial nomenclature?
Answer: Binomial nomenclature is the system of naming organisms using two Latin words — the genus name and the species name.
Q6. What is a herbarium?
Answer: A herbarium is a store of dried, pressed, and preserved plant specimens arranged systematically for study.
Q7. Name the lowest taxonomic category.
Answer: Species is the lowest taxonomic category.
Q8. What is metabolism?
Answer: Metabolism is the sum total of all chemical reactions occurring inside the body of a living organism.
Q9. Define taxonomy.
Answer: Taxonomy is the branch of biology that deals with the identification, nomenclature, and classification of organisms.
Q10. What is a monograph?
Answer: A monograph is a detailed scientific document that contains information about a single taxon.
Q11. What is systematics?
Answer: Systematics is the branch of biology that deals with classification of organisms along with their evolutionary relationships.
Q12. Define homeostasis.
Answer: Homeostasis is the ability of an organism to maintain a stable internal environment despite changes in external conditions.
Short Answer Questions (2-3 Marks)
Q1. What are the defining characteristics of living organisms?
Answer: Living organisms show several distinctive features that separate them from non-living things. The main characteristics are growth, reproduction, metabolism, cellular organisation, response to stimuli, homeostasis, and consciousness. Of these, metabolism and consciousness are considered the most defining features. Growth occurs by cell division from inside the body, and reproduction allows organisms to produce offspring of their own kind, ensuring species continuity.
Q2. Differentiate between growth in living and non-living things.
Answer: In living organisms, growth occurs from inside through cell division and is an intrinsic property. The increase in mass and number of cells is a true sign of growth in life. In non-living things such as a mountain or sand dune, growth occurs by the addition of material from outside (accretion). Therefore, growth alone cannot be considered a defining feature of life, but growth from within is unique to living beings.
Q3. What is taxonomic hierarchy? Mention its categories.
Answer: Taxonomic hierarchy is the arrangement of various taxonomic categories in a descending order. It includes Kingdom, Phylum (Division for plants), Class, Order, Family, Genus, and Species. Each category is called a taxon. Kingdom is the highest while Species is the lowest. As we move from Kingdom to Species, the number of organisms decreases but their similarities increase.
Q4. Explain the rules of binomial nomenclature.
Answer: The main rules of binomial nomenclature are as follows: (i) Names are given in Latin and printed in italics. (ii) The first word denotes the genus and starts with a capital letter. (iii) The second word denotes the species and is written in small letters. (iv) When handwritten, both words must be underlined separately. (v) The author’s name may be written after the species name in abbreviated form, for example Mangifera indica Linn.
Q5. What is the difference between flora, manual, and monograph?
Answer: Flora is a book that contains the actual account of habitat and distribution of plants of a given area. Manuals provide information for identification of names of species found in a particular area. A monograph contains exhaustive information on a particular taxon, such as one species or one genus, including all its known characteristics.
Q6. What is the importance of zoological parks and botanical gardens?
Answer: Zoological parks are places where wild animals are kept in protected environments under human care for conservation, education, and study. Botanical gardens have collections of living plants for reference and identification. Each plant is labelled with its scientific name and family. Both serve as important taxonomic aids and contribute to biodiversity awareness and conservation.
Q7. Why are scientific names preferred over common names?
Answer: Scientific names are preferred because: (i) common names vary from region to region creating confusion, (ii) one organism may have many common names in different languages, (iii) scientific names are universal and recognised worldwide, (iv) they follow internationally accepted rules of ICBN and ICZN, (v) they reveal evolutionary relationships among organisms.
Long Answer Questions (5-7 Marks)
Q1. Describe the major characteristics of living organisms in detail.
Answer: Living organisms show several unique features which distinguish them from non-living matter. (i) Growth: Living beings grow by cell division from within the body, increasing both in size and number of cells. (ii) Reproduction: They reproduce sexually or asexually to produce offspring of their own kind, ensuring continuity of species. (iii) Metabolism: All living things carry out chemical reactions called metabolism, which include both anabolism (building up) and catabolism (breaking down). (iv) Cellular organisation: The body of every organism is composed of one or more cells. (v) Response to stimuli: Living beings sense changes in their environment such as light, sound, temperature, and water and respond accordingly. (vi) Homeostasis: They maintain a stable internal environment despite external changes. (vii) Consciousness: The ability to be aware of surroundings and respond is the most defining feature of life. Together, these features confirm whether a thing is living or non-living.
Q2. Explain taxonomic categories with the example of human beings and mango.
Answer: Taxonomic categories are different ranks used in classification of organisms. There are seven main categories — Kingdom, Phylum/Division, Class, Order, Family, Genus, and Species. For human beings, the classification is: Kingdom – Animalia, Phylum – Chordata, Class – Mammalia, Order – Primata, Family – Hominidae, Genus – Homo, Species – sapiens. For mango, the classification is: Kingdom – Plantae, Division – Angiospermae, Class – Dicotyledonae, Order – Sapindales, Family – Anacardiaceae, Genus – Mangifera, Species – indica. As we move from Kingdom to Species, similarities among organisms increase while the number of organisms in each category decreases. Species, being the lowest unit, contains organisms most similar to each other.
Q3. Describe in detail the various taxonomic aids used in biological studies.
Answer: Taxonomic aids are tools or institutions that help in identification, naming, and classification of organisms. (i) Herbarium: A collection of dried, pressed plant specimens mounted on sheets and arranged according to a universal classification system. (ii) Botanical Gardens: Specialised gardens which have collections of living plants for reference and study. Examples include Indian Botanical Garden, Howrah and Royal Botanical Gardens, Kew. (iii) Museum: Biological museums have collections of preserved plant and animal specimens for study and reference. Animals are preserved in jars containing preservatives or stuffed and mounted. (iv) Zoological Parks: Places where wild animals are kept in protected environments under human care for conservation and study. (v) Key: Analytical tool that uses contrasting characters arranged as couplets. Each statement leads to identification of organisms. (vi) Flora, Manual, and Monograph: Provide information about plants of an area, identification of species, and detailed information of a particular taxon respectively. These aids are indispensable for biodiversity studies.
Q4. What is binomial nomenclature? Why is it necessary? Give an example.
Answer: Binomial nomenclature is the universally accepted scientific naming system for organisms, introduced by Carolus Linnaeus in his book “Species Plantarum” in 1753. Each organism is given a scientific name made up of two parts — the generic name (genus) and the specific epithet (species). For example, the scientific name of mango is Mangifera indica, where Mangifera is the genus and indica is the species. It is necessary because: (i) Common names vary from place to place and language to language causing confusion. (ii) Binomial names are universal and recognised worldwide. (iii) It avoids duplication and confusion. (iv) It indicates relationships among organisms. (v) Names are simple, brief, and based on scientific principles. The rules of binomial nomenclature are governed by the International Code of Botanical Nomenclature (ICBN) and the International Code of Zoological Nomenclature (ICZN).
Q5. Differentiate between herbarium, museum, and botanical garden.
Answer: A herbarium is a store of dried, pressed, and preserved plant specimens mounted on sheets, labelled, and arranged according to a universal system. It serves as a permanent record of plants of a region. A museum is a place that holds collections of preserved plants and animals for study and reference; insects are pinned, larger animals are stuffed, and fish or reptiles may be preserved in jars containing chemicals. A botanical garden, on the other hand, has live plant collections grown for reference, education, and research, with each plant being labelled with its scientific name and family. Together, these aids provide complete material for taxonomic studies and serve as treasure houses of biodiversity.
Q6. Explain the concepts of diversity and classification in the living world.
Answer: The living world shows enormous diversity in form, size, habitat, and behaviour. Over 1.7 to 1.8 million species of plants, animals, fungi, and microorganisms have been identified, and many more are yet to be discovered. This rich variety is referred to as biodiversity. To study such an enormous number of organisms in an organised way, scientists developed the system of classification. Classification is the arrangement of organisms into groups and subgroups based on similarities and differences. The branch of biology that deals with classification is called taxonomy. Systematics goes one step further and includes the evolutionary relationships of organisms. Classification helps in: (i) easy identification, (ii) understanding evolutionary relationships, (iii) economic uses, and (iv) conservation. The basic units of classification are taxa arranged in a hierarchy from Kingdom to Species. Modern classification is based on cellular structure, mode of nutrition, and phylogenetic relationships, with R. H. Whittaker’s Five Kingdom system being widely accepted.
Multiple Choice Questions (MCQs)
Q1. Who is known as the father of taxonomy?
(a) Aristotle
(b) Carolus Linnaeus
(c) Charles Darwin
(d) R. H. Whittaker
Answer: (b) Carolus Linnaeus
Q2. The scientific name of mango is:
(a) Mangifera indica
(b) Musa paradisiaca
(c) Solanum tuberosum
(d) Oryza sativa
Answer: (a) Mangifera indica
Q3. The lowest taxonomic category is:
(a) Kingdom
(b) Genus
(c) Species
(d) Order
Answer: (c) Species
Q4. Which of the following is a defining feature of living organisms?
(a) Growth from outside
(b) Metabolism
(c) Weight
(d) Colour
Answer: (b) Metabolism
Q5. Binomial nomenclature was introduced by:
(a) Aristotle
(b) Carolus Linnaeus
(c) Theophrastus
(d) Hippocrates
Answer: (b) Carolus Linnaeus
Q6. Herbarium is a collection of:
(a) Live plants
(b) Animal specimens
(c) Pressed and dried plants
(d) Microorganisms
Answer: (c) Pressed and dried plants
Q7. The scientific name of human beings is:
(a) Homo sapiens
(b) Homo erectus
(c) Pan troglodytes
(d) Felis catus
Answer: (a) Homo sapiens
Q8. A book containing the description of plants of a region is called:
(a) Manual
(b) Monograph
(c) Flora
(d) Catalogue
Answer: (c) Flora
Q9. Which is the correct sequence of taxonomic categories?
(a) Kingdom > Order > Class > Family
(b) Kingdom > Phylum > Class > Order > Family > Genus > Species
(c) Species > Genus > Family > Order
(d) Phylum > Kingdom > Order > Family
Answer: (b) Kingdom > Phylum > Class > Order > Family > Genus > Species
Q10. Wild animals kept under human care for conservation and study are kept in:
(a) Herbarium
(b) Museum
(c) Botanical garden
(d) Zoological park
Answer: (d) Zoological park
Fill in the Blanks
Q1. The branch of biology that deals with identification, naming, and classification of organisms is called __________.
Answer: taxonomy
Q2. The book “Species Plantarum” was written by __________.
Answer: Carolus Linnaeus
Q3. The sum total of all chemical reactions occurring in a living body is known as __________.
Answer: metabolism
Q4. __________ is the lowest taxonomic category.
Answer: Species
Q5. A detailed account of a particular taxon is given in a __________.
Answer: monograph
Q6. The Five Kingdom system of classification was proposed by __________.
Answer: R. H. Whittaker
Q7. The scientific name of human being is __________.
Answer: Homo sapiens
True or False
Q1. Carolus Linnaeus is known as the father of taxonomy.
Answer: True
Q2. Growth from outside is a defining feature of living organisms.
Answer: False
Q3. Species is the highest taxonomic category.
Answer: False
Q4. Herbarium contains pressed and dried plant specimens.
Answer: True
Q5. Flora is a book that gives the description of plants of a particular area.
Answer: True
Glossary
| Term | Meaning |
|---|---|
| Taxonomy | Branch of biology dealing with classification of organisms |
| Systematics | Study of classification including evolutionary relationships |
| Biodiversity | The variety of living organisms found on Earth |
| Binomial Nomenclature | Two-word naming system introduced by Linnaeus |
| Species | Group of organisms able to interbreed and produce fertile offspring |
| Genus | Group of related species |
| Family | Group of related genera |
| Order | Group of related families |
| Class | Group of related orders |
| Phylum | Group of related classes (used for animals) |
| Division | Group of related classes (used for plants) |
| Kingdom | Highest taxonomic category |
| Taxon | Each level of classification hierarchy |
| Metabolism | Sum of all chemical reactions in living body |
| Homeostasis | Maintenance of stable internal conditions |
| Consciousness | Awareness of and response to surroundings |
| Herbarium | Collection of dried and pressed plant specimens |
| Botanical Garden | Garden with living plant collections for study |
| Museum | Place with preserved plant and animal specimens |
| Zoological Park | Place where wild animals are kept under human care |
| Key | Taxonomic aid using contrasting characters for identification |
| Flora | Book containing description of plants of an area |
| Manual | Document used to identify species in an area |
| Monograph | Detailed work on a single taxon |
| ICBN | International Code of Botanical Nomenclature |
| ICZN | International Code of Zoological Nomenclature |