The Living World - Class 11 Biology - Chapter 1 - Notes, NCERT Solutions & Extra Questions
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Notes - The Living World | Class 11 NCERT | Biology
The Living Kingdom Class 11 Notes: Comprehensive Guide & Summary
Introduction to The Living Kingdom Class 11 Notes
Biology is the science of life forms and living processes. The living world encompasses an astonishing diversity of organisms, from microscopic bacteria to massive whales. This guide will help you understand the core concepts and classifications outlined in the Class 11 Biology syllabus.
Understanding the Living World
The living world is rich in variety. The millions of plants and animals identified and described so far are just a fraction of the biodiversity on Earth. The classification of organisms into a systematic hierarchy helps scientists understand their relationships and interactions.
Diversity in the Living World
Living organisms thrive in diverse habitats such as cold mountains, deciduous forests, oceans, lakes, deserts, and hot springs. Each species, varying from potted plants to unseen microscopic organisms, adds to the vast tapestry of life, which is referred to as biodiversity.
Nomenclature in the Living Kingdom
To avoid confusion arising from local names, scientists have established a universal system of naming organisms. This standardisation is called nomenclature. The International Code for Botanical Nomenclature (ICBN) and International Code of Zoological Nomenclature (ICZN) provide guidelines for naming plants and animals, respectively.
Binomial Nomenclature
Binomial nomenclature, introduced by Carolus Linnaeus, is a two-term naming system in Latin, comprising the genus and the specific epithet. For example, the scientific name of the mango is Mangifera indica.
Classification and Taxonomic Categories
Classification is the sorting and grouping of organisms into categories based on shared characteristics. The hierarchical system of classification includes multiple ranks: Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Detailed Look at Taxonomic Categories
Species
A species is the basic unit of classification, defined as a group of organisms sharing fundamental similarities, capable of interbreeding. For instance, Homo sapiens is the species name for humans.
Genus
A genus comprises related species that exhibit more common characters compared to species of other genera. For example, lions (Panthera leo), tigers (Panthera tigris), and leopards (Panthera pardus) belong to the genus Panthera.
Family
Families are composed of related genera with fewer similarities. For example, the family Felidae includes the genera Panthera (lions, tigers) and Felis (cats).
Order
Orders are identified based on aggregated families sharing a set of similar characters. For example, the order Carnivora includes the families Felidae (cats) and Canidae (dogs).
Class
Classes group related orders together. For example, the class Mammalia includes orders Primata (monkeys, apes) and Carnivora (cats, dogs).
Phylum
Phylum is a higher taxonomic category that includes different classes. For example, the phylum Chordata includes classes like Mammalia, Aves (birds), and Reptilia (reptiles).
Kingdom
Kingdom is the highest taxonomic rank, encompassing all organisms with fundamental similarities. The two primary kingdoms are Animalia (animals) and Plantae (plants).
graph TD
K[Kingdom Animalia] --> P[Phylum Chordata]
P --> C[Class Mammalia]
C --> O[Order Primata]
O --> F[Family Hominidae]
F --> G[Genus Homo]
G --> S[Species sapiens]
Systematics and Evolutionary Relationships
Systematics is the study of the relationships between organisms and their evolutionary history. It includes taxonomy (classification), nomenclature (naming), and identification. Systematics helps understand the shared ancestry and evolutionary pathways of organisms.
Key Contributions and Figures
Ernst Mayr, one of the 20th century’s most influential biologists, revolutionised our understanding of species diversity and evolution. Awarded the Balzan Prize, the International Prize for Biology, and the Crafoord Prize, Mayr's work laid the foundation for modern taxonomy and biological classification.
Practical Applications and Study Resources
Taxonomic studies are critical in fields like agriculture, medicine, and environmental science. Understanding the classification of organisms helps in conserving biodiversity, discovering new species, and enhancing crop and animal breeding programs.
Conclusion
The study of the living world through classifications such as taxonomic categories broadens our understanding of biodiversity and its significance. It is crucial for scientific communication, conservation efforts, and the advancement of biological sciences.
This comprehensive guide summarises the key points of "The Living Kingdom" as outlined in Class 11 biology, providing a clear understanding of the diverse and interconnected world of living organisms.
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NCERT Solutions - The Living World | NCERT | Biology | Class 11
Why are living organisms classified?
Living organisms are classified to facilitate the study of their immense diversity. Classification helps in organizing millions of species into categories based on their characteristics, making it easier to study, identify, and name them universally. It aids in understanding the relationships among different organisms and aids in agriculture, forestry and industry by providing a structured way of accessing biological information.
Why are the classification systems changing every now and then?
Classification systems are constantly evolving due to a number of reasons:
Discovery of New Species: As new species are continually discovered, the classification system needs to be updated to accommodate them.
Advances in Technology: Modern techniques, especially in genetics and molecular biology, provide new data that can lead to reclassification of species based on genetic relationships rather than just morphological characteristics.
Better Understanding of Evolutionary Relationships: Ongoing research helps in understanding the evolutionary relationships between different organisms better, which can lead to changes in their classification.
Correction of Past Misclassifications: As our understanding improves, historical inaccuracies in classifications are corrected to better reflect true relationships among species.
By staying adaptable, classification systems aim to provide a more accurate and comprehensive understanding of the diversity of life.
What different criteria would you choose to classify people that you meet often?
To classify people that you meet often, here are some different criteria you can choose to use:
Relationship (e.g., family, friends, colleagues, acquaintances).
Occupation/Profession (e.g., doctor, teacher, engineer).
Age Group (e.g., children, teenagers, adults, the elderly).
Gender (e.g., male, female, non-binary).
Interests/Hobbies (e.g., sports enthusiasts, readers, musicians).
Location/Proximity (e.g., neighbors, people from the same town).
Frequency of Interaction (e.g., daily, weekly, monthly encounters).
Personality Traits (e.g., introverts, extroverts, calm, energetic).
Social Roles (e.g., team leader, mentor, peer).
These criteria help in systematising interactions and understanding social dynamics better, similar to how organisms are classified in taxonomy based on shared characteristics.
What do we learn from identification of individuals and populations?
From the identification of individuals and populations, we learn the following:
Correct Naming: It ensures that each organism has one universally accepted name, avoiding confusion caused by local or regional names.
Systematic Study: It allows biologists to organize and study organisms systematically by assigning them to appropriate taxa.
Understanding Relationships: It helps in identifying similarities and differences among organisms, which can reveal evolutionary relationships.
Biodiversity Conservation: By identifying different species, we can monitor and conserve biodiversity effectively.
Resource Identification: It aids in recognizing and utilizing biological resources efficiently for agriculture, forestry, industry, and other purposes.
Given below is the scientific name of Mango. Identify the correctly written name.
Mangifera Indica
Mangifera indica
The correctly written scientific name of Mango is Mangifera indica.
According to the Binomial nomenclature rules:
The first word (genus) starts with a capital letter.
The second word (specific epithet) starts with a small letter.
The entire name is written in italics when printed.
Define a taxon. Give some examples of taxa at different hierarchical levels.
A taxon (plural: taxa) is a unit of classification in biological taxonomy, representing a group of one or more organisms that exhibit common characteristics and are assigned a category in a hierarchically structured system of classification. Taxa can represent categories at different hierarchical levels, such as species, genus, family, order, class, phylum, and kingdom.
Examples of Taxa at Different Hierarchical Levels:
Species:
Homo sapiens (humans)
Mangifera indica (mango)
Genus:
Homo (includes species like Homo sapiens)
Panthera (includes species like Panthera leo (lion), Panthera tigris (tiger))
Family:
Hominidae (includes genera like Homo)
Felidae (includes genera like Panthera and Felis)
Order:
Primata (includes families like Hominidae)
Carnivora (includes families like Felidae and Canidae (dogs))
Class:
Mammalia (includes orders like Primata and Carnivora)
Insecta (includes orders like Diptera)
Phylum:
Chordata (includes classes like Mammalia and Aves (birds))
Arthropoda (includes classes like Insecta)
Kingdom:
Animalia (includes phyla like Chordata and Arthropoda)
Plantae (includes divisions like Angiospermae (flowering plants))
Key Points
Taxa are groups of organisms classified together based on shared characteristics.
Each hierarchical level represents a different rank or category, ranging from broad (kingdom) to specific (species).
Examples illustrate how organisms are classified at each taxonomic level.
Table: Examples of Taxa
Hierarchical Level | Example |
---|---|
Species | Homo sapiens (human) |
Genus | Panthera (includes lions, tigers) |
Family | Felidae (cats, lions, tigers) |
Order | Carnivora (includes Felidae and Canidae) |
Class | Mammalia (includes mammals such as humans, dogs) |
Phylum | Chordata (includes vertebrates like birds, mammals) |
Kingdom | Animalia (all animals) |
By understanding taxa and their hierarchical classification, we can better appreciate the diversity and relationships among various living organisms.
Can you identify the correct sequence of taxonomical categories?
(a) Species $\rightarrow$ Order $\rightarrow$ Phylum $\rightarrow$ Kingdom
(b) Genus $\rightarrow$ Species $\rightarrow$ Order $\rightarrow$ Kingdom
(c) Species $\rightarrow$ Genus $\rightarrow$ Order $\rightarrow$ Phylum
The correct sequence of taxonomical categories is:
(c) Species $\rightarrow$ Genus $\rightarrow$ Order $\rightarrow$ Phylum
Try to collect all the currently accepted meanings for the word 'species'. Discuss with your teacher the meaning of species in case of higher plants and animals on one hand, and bacteria on the other hand.
Accepted Meanings of 'Species'
General Definition: A species is a group of individual organisms that share common characteristics and can interbreed to produce fertile offspring.
Biological Species Concept: This concept defines species based on reproductive isolation, meaning members of a species can interbreed and produce fertile offspring, but cannot do so with members of other species.
Morphological Species Concept: This concept classifies species based on physical and structural features.
Phylogenetic Species Concept: This concept defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
Ecological Species Concept: This defines a species based on its ecological niche, i.e., the role a species plays in its environment.
Discussion Points
In Higher Plants and Animals: The biological species concept is often used. In these organisms, species are usually defined by their ability to interbreed and produce fertile offspring. Morphological features and genetic information are also considered for species classification.
In Bacteria: The concept of species is more complex and often includes elements of the phylogenetic and ecological species concepts. Bacteria do not follow the sexual reproduction patterns seen in higher plants and animals. Instead, species classification often relies on genetic, ecological, and biochemical characteristics.
Define and understand the following terms:
(i) Phylum
(ii) Class
(iii) Family
(iv) Order
(v) Genus
(i) Phylum
Definition: A phylum is a category in the taxonomic hierarchy that ranks above class and below kingdom. It includes one or more classes of organisms that share a common structure and evolutionary ancestry. Example: In the animal kingdom, the phylum Chordata includes vertebrates like humans, birds, fishes, amphibians, and reptiles.
(ii) Class
Definition: A class is a group of related orders that share several common characteristics. It ranks above order and below phylum. Example: The class Mammalia includes animals like humans, lions, and whales, characterized by the presence of mammary glands.
(iii) Family
Definition: A family consists of one or more genera that share a number of similarities. It ranks above genus and below order. Example: The family Felidae includes genera such as Panthera (lions, tigers) and Felis (domestic cats).
(iv) Order
Definition: An order is a higher taxonomic category than family and is composed of several families sharing certain morphological traits. Example: The order Primata includes families such as Hominidae (humans, great apes) and Cercopithecidae (old world monkeys).
(v) Genus
Definition: A genus comprises a group of related species that are very similar to one another. It ranks above species and below family. Example: The genus Panthera includes species such as Panthera leo (lion), Panthera tigris (tiger), and Panthera pardus (leopard).
These hierarchical categories help in the scientific classification and understanding of the relationships among different organisms.
Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.
The taxonomical hierarchy is a system of classification that organizes living organisms into progressively broader categories based on shared characteristics. Here is a detailed illustration using the examples of a plant (Wheat - Triticum aestivum) and an animal (Human - Homo sapiens):
Taxonomic Category | Human (Animal) | Wheat (Plant) |
---|---|---|
Kingdom | Animalia | Plantae |
Phylum/Division | Chordata | Angiospermae |
Class | Mammalia | Monocotyledonae |
Order | Primata | Poales |
Family | Hominidae | Poaceae |
Genus | Homo | Triticum |
Species | Homo sapiens | Triticum aestivum |
Key points:
Kingdom: The broadest category. Example: All animals belong to the Kingdom Animalia, and all plants belong to the Kingdom Plantae.
Phylum/Division: Groups organisms based on major body plans or structures. Example: Humans are in Chordata (presence of notochord), and Wheat is in Angiospermae (flowering plants).
Class: Groups organisms with even more specific common traits. Example: Humans are in Mammalia (mammals), and Wheat is in Monocotyledonae (monocots).
Order: Further groups classes into orders based on additional similarities. Example: Humans are in Primata (primates), and Wheat is in Poales.
Family: A more specific grouping within orders. Example: Humans are in Hominidae (great apes), and Wheat is in Poaceae (grass family).
Genus: Groups species that are very similar and closely related. Example: Humans are in Homo, and Wheat is in Triticum.
Species: The most specific category, identifying individual types of organisms. Example: Humans are Homo sapiens, and Wheat is Triticum aestivum.
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Ask Chatterbot AIExtra Questions - The Living World | NCERT | Biology | Class 11
- Which of the following organizations bring out the report known as 'The Living Planet Report'?
A) (a) WWF (World Wildlife Fund)
B) (b) The United Nations Development Programme
C) (c) The World Economic Forum
D) (d) The World Bank
The correct answer is A.
WWF (World Wildlife Fund) is the organization responsible for publishing the 'The Living Planet Report'. This report provides an analysis of the state of the planet's wildlife based on ecological research.
"The Dead Sea has a variety of sea life inside it."
A) True
B) False
The correct answer is B - False.
False. The Dead Sea's salt concentration is exceptionally high, making it inhospitable for aquatic life forms. The salinity is so extreme that it prevents human or animal life from flourishing there and also causes individuals to float rather than sink due to the increased buoyancy.
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