The Living World -Overview, Topics, Characteristics, Books, Tips

What is the Living World?

The Living World contains a vast diversity of plants and animals. It explains how organisms are classified based on growth, reproduction, metabolism, and response to stimuli. The cells are the basic unit of life. The cells of an organism show metabolic changes in the use of carbon-based compounds to grow or reproduce.

Through the process of natural selection, millions of generations have been shaped from primitive forms of life to complex organisms into what we observe today. The age of some fossils is 3.5 to 3.7 billion years, highlighting the ancient origins of biodiversity.

The world of living organisms has a variety of life forms, ranging from the minute bacteria to plants and animals. Despite their diversity in ecosystems, all living organisms share fundamental traits:

• All living organisms display growth, development, and metabolic activity.

• They can reproduce to produce offspring of their species.

• Living organisms react to environmental stimuli (consciousness).

• Biodiversity captures the vast array of living organisms in various habitats.

Also Read:

• Biological Classification

• Scientific Names of Animals And Plants

• Biological Classification Basis

Characteristics of the Living Organisms

The characteristics of the living beings are given below-

• Growth: All living organisms reproduce either by an increase in size or by cell number.

• Reproduction: Living organisms can produce offspring either sexually or asexually.

• Metabolism: They carry out a range of biochemical reactions inside their cells to maintain life, unique to living organisms.

• Cellular Organisation: All living organisms are made up of cells and, as such, constitute the basic unit of life.

• Response to Stimuli: The living organism responds to changes in the environment, such as light and temperature.

• Adaptation: They learn to adapt over time to their environment to help them survive.

• Homeostasis: Living organisms will try to maintain an internal environment despite external changes.

• Life cycle: They have a defined cycle in their life from birth to growth, reproduction, and then death.

Composition of the Living World

The living world consists of diverse components forming the foundation of Earth and has characteristics in the context of structure and function that define all living organisms from the molecular to complex ecological interactions. The basics are discussed below:

• Biomolecules: Basic building blocks, which are proteins, carbohydrates, lipids, and nucleic acids needed for life functions.

• Cells: The prime units of life, they can be either single-celled or multicelled.

• Energy Flow: The organisms may obtain energy through photosynthesis or by consuming other organisms.

• Genetic Material: DNA/RNA has genetic information needed for the reproduction and evolution of life forms.

• Diversity and Classification: Kingdoms are divided into (Monera, Protista, Fungi, Plantae, and Animalia) based on structure and evolutionary relationships.

• Interactions and Ecology: Interactions of organisms keep ecological balance and nutrient cycles in check.

Binomial Nomenclature

The binomial nomenclature concept was introduced by Carl Linnaeus. It is the universal system of naming organisms. Each species has a two-part name:

• Genus name- written first and capitalised

• Species name (lowercase)- written second and lowercase

Example: Panthera leo (lion)

This system avoids confusion and ensures uniformity in scientific communication. It is widely used in taxonomy, biodiversity studies, and NEET Biology preparation. It helps students understand how organisms are classified and identified across the world.

Taxonomical Aids Class 11

Taxonomy is the field of biology that addresses the identification, naming, and classification of living things. It classifies species into a hierarchical system according to common features to make it simpler to study biodiversity. Kingdom, phylum, class, order, family, genus, and species are the main taxonomic ranks. Taxonomical aids are essential tools for identifying, naming, and classifying organisms. They help students and researchers study biodiversity systematically.

• Herbarium – A preserved plant collection used in scientific study and as a reference.

• Botanical Garden – An area where various plant species are cultivated for study, learning, and conservation.

• Museum – An institution in which specimens of animals, plants, and fossils are preserved for study and exhibition to the general public.

• Zoological Park – An institution where live animals are housed in a nature-mimicking environment for conservation and education.

Taxonomic Hierarchy NEET

Taxonomy organises species into a hierarchical system for easy study of biodiversity. Taxonomic Hierarchy begins with species, the most basic unit, and is defined as such organisms sharing the essential characteristics. The 7 levels of taxonomic categories are given below-

• Kingdom: The highest rank, grouping organisms based on broad characteristics (e.g., Animalia, Plantae).

• Phylum/Division: Divides kingdoms into groups with more specific similarities (e.g., Chordata in Animalia or Angiosperms in Plantae).

• Class: Groups organisms within a phylum (e.g., Mammalia in Chordata).

• Order: Further divides classes based on additional similarities (e.g., Carnivora in Mammalia).

• Family: Groups related genera (e.g., Felidae in Carnivora).

• Genus: Groups species with close similarities (e.g., Panthera in Felidae).

• Species: The basic unit of classification, representing organisms that can interbreed (e.g., Panthera leo for lions)

MCQs on The Living World NEET

Question: Growth cannot be taken as a defining property of living organisms because

1. All living organisms do not show growth

2. Non-living things also grow from inside

3. On-living things can also grow by increasing in mass

4. Some living organisms do not show the process of reproduction

Correct Answer: 3) On-living things can also grow by increasing in mass

Explanation:

Growth is not considered a defining property of living organisms because non-living things show external growth by the accumulation of materials. In living organisms, growth involves both internal and external changes, with cells dividing and increasing in size. This growth is regulated by genetic information and occurs through metabolic processes that require energy. Non-living things, on the other hand, may grow externally through the accumulation of matter, like crystals or minerals, without any internal cellular processes. Therefore, growth alone is not sufficient to define life, as it does not account for the complexity and regulation seen in living organisms.

Hence, the correct answer is option 3) On-living things can also grow by increasing in mass

Question: In the majority of higher plants and animals, ______ and ________ are mutually exclusive events.

1. Growth, nutrition

2. Nutrition, consciousness

3. Growth, reproduction

4. Reproduction, consciousness

Correct Answer: 3)Growth, reproduction

Explanation:

Living things display growth, development, responsiveness or irritability, adaptation, and reproduction. They are cellular, meaning protoplasm is found in cells, but viruses are not. Metabolism is a chemical activity, which consists of two main types- anabolic or building of complex substances, and catabolic or breakdown of substances. Living organisms react to stimuli, regulate their internal environment, adapt to both biological and physical environments, and die. Single-celled organisms grow by fission but maintain their identity.

Hence, the correct answer is Option (3) Growth, reproduction

Question: Binomial nomenclature means

1. One name given by two taxonomists

2. Two names, one Latinized, the other of a person

3. Two names, one scientific, the other local

4. Two-word names, the first indicates the genus and other species

Correct Answer: 4) Two-word names, the first indicates genus and the second species

Explanation:

Binomial Nomenclature - It is a system of naming organisms, in which it is given only one name consisting of two words. The first word is the generic name and the second is the specific name. E.g Homo sapiens, Mangifera indica, Ocimum sanctum. It was given by Carolus Linnaeus. Binomial nomenclature is the system of providing a name consisting of two words -- first generic and second specific. Example - Homo sapiens, Homo =genus , sapiens = species

Hence, the correct answer is option 4)Two-word names, the first indicates genus and other species.

Other useful Resources:

• Virus
• Archaebacteria
• Prions

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