The Living World: Revision Notes for NEET 2023

Introduction

The living world is a vast and diverse place, and it is important to understand the basic characteristics of living organisms in order to study them further. Some of the key characteristics of living organisms include:

• Growth: Living organisms grow and develop over time. This growth can be either quantitative (an increase in size) or qualitative (an increase in complexity).
• Metabolism: Living organisms are able to convert energy from their surroundings into forms that they can use. This process of metabolism is essential for life, as it provides the energy that living organisms need to carry out all of their activities.
• Reproduction: Living organisms are able to produce offspring that are similar to themselves. This process of reproduction ensures that the genetic information of living organisms is passed on to future generations.
• Adaptation: Living organisms are able to adapt to their environment. This adaptation can be either physical (changes in the organism’s body) or behavioral (changes in the organism’s behavior).
• Organization: Living organisms are organized at various levels, from the smallest unit of life (the cell) to the largest unit of life (the ecosystem).
• Homeostasis: Living organisms are able to maintain a relatively constant internal environment, even though the external environment is constantly changing. This process of homeostasis is essential for life, as it allows living organisms to function properly.
• Classification of Living Organisms

Living organisms are classified into different groups based on their shared characteristics. The most basic level of classification is the kingdom. There are five kingdoms of living organisms:

* **Monera:** Prokaryotic organisms that do not have a nucleus or other membrane-bound organelles.
* **Protista:** Eukaryotic organisms that are unicellular or simple multicellular.
* **Plantae:** Eukaryotic organisms that are multicellular and produce their own food through photosynthesis.
* **Animalia:** Eukaryotic organisms that are multicellular and consume other organisms for food.
* **Fungi:** Eukaryotic organisms that are multicellular and decompose organic matter.

Within each kingdom, there are further levels of classification, such as phyla, classes, orders, families, genera, and species. The species is the most specific level of classification, and it represents a group of organisms that can interbreed and produce fertile offspring.

The taxonomic hierarchy is a hierarchical system of classification that is used to organize living organisms. It is based on shared characteristics, and it allows us to group organisms together based on their evolutionary relationships. The taxonomic hierarchy is a powerful tool for understanding the diversity of life on Earth.

What is Taxonomic Hierarchy

Here are some additional notes about the taxonomic hierarchy:

• The hierarchy is hierarchical, which means that each level of classification is nested within the next. For example, the genus Panthera is nested within the family Felidae, which is nested within the order Carnivora, and so on.
• The hierarchy is based on shared characteristics. This means that organisms that are classified together share certain characteristics that distinguish them from other organisms. For example, all organisms in the genus Panthera are large cats with a mane of hair.
• The hierarchy is a dynamic system. This means that it is constantly being updated as new information about living organisms is discovered. For example, new species are being discovered all the time, and the taxonomic hierarchy is being updated to reflect these discoveries.

What Is Taxon?

A taxon is a group of organisms that are classified together based on their shared characteristics. The term “taxon” is pluralized as “taxa.”

The categories of classification are:

• Kingdom: The kingdom is the broadest level of classification. There are five kingdoms of living organisms: Monera, Protista, Plantae, Fungi, and Animalia.
• Phylum: The phylum is the next level of classification after the kingdom. There are many different phyla, each of which includes a group of organisms that share certain characteristics.
• Class: The class is the third level of classification after the kingdom and phylum. There are many different classes, each of which includes a group of organisms that share certain characteristics.
• Order: The order is the fourth level of classification after the kingdom, phylum, and class. There are many different orders, each of which includes a group of organisms that share certain characteristics.
• Family: The family is the fifth level of classification after the kingdom, phylum, class, and order. There are many different families, each of which includes a group of organisms that share certain characteristics.
• Genus: The genus is the sixth level of classification after the kingdom, phylum, class, order, and family. There are many different genera, each of which includes a group of organisms that share certain characteristics.
• Species: The species is the most specific level of classification. A species is a group of organisms that can interbreed and produce fertile offspring.

It is important to note that the taxonomic hierarchy is not always a perfect representation of evolutionary relationships. Sometimes, organisms that are closely related are classified in different taxa, while organisms that are not closely related are classified in the same taxa. This is because the taxonomic hierarchy is based on shared characteristics, and not on evolutionary relationships.

Despite its limitations, the taxonomic hierarchy is a useful tool for understanding the diversity of life on Earth. It allows us to group organisms together based on their shared characteristics, and it helps us to see how organisms are related to each other.

What is Taxonomic Rank or Category ?

Taxonomic rank refers to a level of classification in a hierarchical system of classifying living things. In this system, organisms are grouped into different categories based on their shared characteristics. The most basic level of classification is the kingdom, and the most specific level is the species.

There are seven taxonomic ranks commonly used:

• Domain: A domain is the highest rank in the taxonomic hierarchy. There are three domains of living organisms: Bacteria, Archaea, and Eukarya.
• Kingdom: A kingdom is the next level of classification after the domain. There are five kingdoms of living organisms: Monera, Protista, Plantae, Fungi, and Animalia.
• Phylum: A phylum is the third level of classification after the kingdom. There are many different phyla, each of which includes a group of organisms that share certain characteristics.
• Class: A class is the fourth level of classification after the kingdom and phylum. There are many different classes, each of which includes a group of organisms that share certain characteristics.
• Order: An order is the fifth level of classification after the kingdom, phylum, and class. There are many different orders, each of which includes a group of organisms that share certain characteristics.
• Family: A family is the sixth level of classification after the kingdom, phylum, class, and order. There are many different families, each of which includes a group of organisms that share certain characteristics.
• Genus: A genus is the seventh and most specific level of classification after the kingdom, phylum, class, order, and family. There are many different genera, each of which includes a group of organisms that share certain characteristics.

Taxonomic ranks are not always mutually exclusive. For example, an organism can belong to multiple genera. This is because taxonomic ranks are based on shared characteristics, and not on evolutionary relationships.

Despite its limitations, the taxonomic hierarchy is a useful tool for understanding the diversity of life on Earth. It allows us to group organisms together based on their shared characteristics, and it helps us to see how organisms are related to each other.

The taxonomic hierarchies for panthera, mango, housefly, and humans:

Panthera

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Carnivora
• Family: Felidae
• Genus: Panthera
• Species: Panthera tigris

Mango

• Kingdom: Plantae
• Phylum: Magnoliophyta
• Class: Magnoliopsida
• Order: Sapindales
• Family: Anacardiaceae
• Genus: Mangifera
• Species: Mangifera indica

Housefly

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta
• Order: Diptera
• Family: Muscidae
• Genus: Musca
• Species: Musca domestica

• Humans

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Genus: Homo
• Species: Homo sapiens

Classification of Datura, Petunia and Potato

Datura

• Domain: Eukarya
• Kingdom: Plantae
• Phylum: Magnoliophyta
• Class: Magnoliopsida
• Order: Solanales
• Family: Solanaceae
• Genus: Datura
• Species: Datura stramonium

Potato

• Domain: Eukarya
• Kingdom: Plantae
• Phylum: Magnoliophyta
• Class: Magnoliopsida
• Order: Solanales
• Family: Solanaceae
• Genus: Solanum
• Species: Solanum tuberosum

Petunia

• Domain: Eukarya
• Kingdom: Plantae
• Phylum: Magnoliophyta
• Class: Magnoliopsida
• Order: Solanales
• Family: Solanaceae
• Genus: Petunia
• Species: Petunia hybrida

As you can see, all three plants belong to the same family, Solanaceae. This means that they share many common characteristics, such as the presence of flowers with four petals and a star-shaped corolla. However, they also have some distinguishing characteristics. For example, datura has white or purple flowers with a strong, unpleasant odor, while potato has white flowers with a mild odor. Petunia, on the other hand, has a wide variety of flower colors, including white, purple, red, and yellow.thumb_upthumb_downtuneshareGoogle it

Diversity of Living Organisms

The living world is incredibly diverse, with an estimated 1.8 million different species. This diversity is found in the different types of organisms that exist, as well as in the different ways that organisms adapt to their environment.

The living world is incredibly diverse, with millions of different species of plants, animals, fungi, and bacteria. This diversity is essential for the health of the planet, as it allows different organisms to fill different ecological niches.

One of the most important aspects of the diversity of the living world is its classification. Organisms are classified into groups based on their shared characteristics, which helps scientists to study and understand them. The most common system of classification is the taxonomic hierarchy, which organizes organisms into categories such as domains, kingdoms, phyla, classes, orders, families, genera, and species.

The living world is also characterized by its diversity of habitats. Organisms can be found in a wide range of environments, from the depths of the oceans to the tops of mountains. This diversity of habitats is essential for the survival of the living world, as it allows different organisms to find the conditions they need to thrive.

The diversity of the living world is constantly changing. New species are being discovered all the time, and existing species are evolving and adapting to new environments. This diversity is essential for the future of the planet, as it allows the living world to adapt to change and survive.

Here are some resources you can use to learn more about the diversity of the living world:

• The NCERT textbook “The Living World”
• The website of the National Center for Biotechnology Information (NCBI)
• The website of the Encyclopedia of Life
• The website of the Global Biodiversity Information Facility

I hope this article has helped you to learn more about the diversity of the living world.

Importance of Studying the Living World

The living world is essential to our existence. We depend on living organisms for food, shelter, and other resources. Studying the living world can help us to understand how organisms function, how they interact with each other, and how they are affected by their environment. This knowledge can be used to develop new technologies, improve our understanding of health and disease, and protect the environment.

Taxonomic Aids

Taxonomic aids are tools that are used to identify and classify living organisms. They include:

• Herbarium: A herbarium is a collection of dried and pressed plant specimens. It is a valuable resource for botanists, as it allows them to study the diversity of plant life and to identify new species.
• Museum: A museum is a place where collections of objects are preserved and displayed for public education and research. Museums often have collections of preserved animals, plants, and other organisms.
• Botanical garden: A botanical garden is a place where plants are grown for scientific research and for public display. Botanical gardens often have collections of rare and endangered plants.
• Zoological park: A zoological park is a place where animals are kept in captivity for scientific research and for public display. Zoological parks often have collections of animals from all over the world.
• Keys: Taxonomic keys are a type of dichotomous key that is used to identify organisms. Dichotomous keys consist of a series of paired statements. The user chooses the statement that best describes the organism they are trying to identify. This leads them to another pair of statements, and so on, until the organism has been identified.
• Monographs: Monographs are comprehensive works on a particular group of organisms. They provide detailed information on the taxonomy, morphology, ecology, and distribution of the organisms in the group.
• Manuals: Manuals are shorter and more concise than monographs. They provide basic information on the identification and classification of organisms.
• Flora: A flora is a book that lists all of the plants that occur in a particular area. Floras typically provide information on the taxonomy, morphology, ecology, and distribution of the plants in the area.
• Catalogues: Catalogues are lists of the specimens that are held in a particular collection. They can be used to identify organisms that are not included in other taxonomic aids.
• Taxonomic aids are essential tools for the study of living organisms. They allow us to identify and classify organisms, to study their diversity, and to understand their evolutionary relationships.

Multiple choice questions for the chapter “The Living World”:

1. Which of the following is NOT a characteristic of living organisms?
   • A. Growth
   • B. Metabolism
   • C. Reproduction
   • D. Non-living
2. Which of the following is the most basic level of classification in the taxonomic hierarchy?
   • A. Species
   • B. Genus
   • C. Family
   • D. Kingdom
3. Which of the following is NOT a kingdom of living organisms?
   • A. Monera
   • B. Protista
   • C. Fungi
   • D. Animalia
4. Which of the following is the correct taxonomic hierarchy for a human?
   • A. Animalia > Chordata > Mammalia > Primates > Homo > Sapiens
   • B. Animalia > Chordata > Mammalia > Homo > Sapiens > Primates
   • C. Primates > Animalia > Homo > Sapiens > Chordata > Mammalia
   • D. Sapiens > Homo > Primates > Animalia > Chordata > Mammalia
5. Which of the following is NOT a taxonomic aid?
   • A. Monograph
   • B. Museum
   • C. Flora
   • D. Dichotomous key
6. Which of the following is NOT a characteristic of a species?
   • A. Members of a species can interbreed and produce fertile offspring.
   • B. Members of a species have the same DNA.
   • C. Members of a species live in the same habitat.
   • D. Members of a species have the same morphology.
7. Which of the following is the correct sequence of the taxonomic hierarchy, from the broadest to the most specific?
   • A. Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
   • B. Kingdom > Phylum > Class > Order > Family > Genus > Species > Domain
   • C. Phylum > Kingdom > Class > Order > Family > Genus > Species > Domain
   • D. Species > Genus > Family > Order > Class > Phylum > Kingdom > Domain
8. Which of the following is a characteristic of prokaryotic cells?
   • A. They have a nucleus.
   • B. They have a cell membrane.
   • C. They have DNA.
   • D. They have organelles.
9. Which of the following is a characteristic of eukaryotic cells?
   • A. They have a nucleus.
   • B. They have a cell membrane.
   • C. They have DNA.
   • D. All of the above
10. Which of the following is NOT a part of the cell theory?
    • A. All living organisms are made up of cells.
    • B. Cells are the basic units of structure and function of all living organisms.
    • C. Cells come from preexisting cells.
    • D. Cells can be seen with the naked eye.
11. Which of the following is the correct order of the levels of organization in living organisms, from the simplest to the most complex?
    • A. Atoms > molecules > cells > tissues > organs > organ systems > organism
    • B. Atoms > molecules > cells > tissues > organs > organism > organ systems
    • C. Molecules > atoms > cells > tissues > organs > organ systems > organism
    • D. Molecules > cells > tissues > organs > organ systems > organism > atoms
12. Which of the following is NOT a type of tissue?
    • A. Epithelial tissue
    • B. Connective tissue
    • C. Muscle tissue
    • D. Nervous tissue
13. Which of the following is NOT an organ system?
    • A. Digestive system
    • B. Circulatory system
    • C. Respiratory system
    • D. Skeletal system
14. Which of the following is NOT a characteristic of an ecosystem?
    • A. It is a community of living organisms and their non-living environment.
    • B. It is self-sustaining.
    • C. It is a closed system.
    • D. It is constantly changing.

15. Which of the following is NOT a component of the biosphere?
    • Atmosphere
    • Lithosphere
    • Hydrosphere
    • None of the above
16. Which of the following is NOT a factor that affects the distribution of living organisms?
    • Climate
    • Soil
    • Water
    • Gravity
17. Which of the following is NOT a type of adaptation?
    • Behavioral adaptation
    • Physiological adaptation
    • Ecological adaptation
    • Morphological adaptation
18. Which of the following is NOT a type of natural selection?
    • Directional selection
    • Stabilizing selection
    • Disruptive selection
    • Naturalistic selection
19. Which of the following is NOT a threat to biodiversity?
    • Habitat loss
    • Overpopulation
    • Pollution
    • Climate change
20. Which of the following is NOT a goal of conservation biology?
    • To protect endangered species
    • To restore degraded ecosystems
    • To educate the public about the importance of biodiversity
    • To develop new technologies to help conserve biodiversity

Answers

The answers to the multiple choice questions:

1. A. Non-living
2. D. Kingdom
3. C. Fungi
4. A. Animalia > Chordata > Mammalia > Primates > Homo > Sapiens
5. C. Flora
6. C. Members of a species live in the same habitat.
7. A. Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
8. A. They have a nucleus.
9. D. All of the above
10. D. Cells can be seen with the naked eye.
11. A. Atoms > molecules > cells > tissues > organs > organ systems > organism
12. D. Skeletal system
13. D. Skeletal system
14. C. It is a closed system.
15. D. None of the above
16. D. Gravity
17. E. Ecological adaptation
18. C. Naturalistic selection
19. C. Pollution
20. C. To develop new technologies to help conserve biodiversity

I hope these answers help you to test your knowledge of the chapter “The Living World.”

Also Read: Human Health And Diseases Revision Notes