Why Diversity in Living Organisms Matters in Biology
Biodiversity is used to define the diversity of life forms worldwide. It is a word that is used more often to refer to the classification of living species found in a particular geographic region. The Diversity of living species of a geographic region in an area provides stability in the respective region.
There are numerous living organisms on earth with different sizes, shapes, habitats, nutrition, reproduction, and more. That depends on their physical features and their habitat. Animals of any kingdom are classified into different orders and classes.
Animals live in different climates like water, land, grasslands, deserts, forests, ice, water, and ice to forests, deserts, and grasslands. All these organisms consist of cells.
Cells are one of the essential characteristics of living organisms. Cells are structural units of life. It carries out specifically assigned functions in living species. In this way, a group of cells from tissue in living species.
Diversity in living organisms can be seen everywhere on earth. The region of the earth is highly diverse and is called the region of mega biodiversity. Twelve countries in the world have more than half of the biodiversity in the world. India is also one of them.
Over millions of years, diversity has been going on in living beings. Species have evolved from ape-like beings to homo sapiens. People look for similarities between organisms to classify them, and hence they study them as a whole. Regarding this, fundamental characteristics need to be decided, which would form the foundation for classifying.
Introduction to Diversity in Living Organisms
Life exists in different forms on Earth. When it comes to the question of the number of living organisms found on the earth, the answer is unimaginable. This is so because of the large diversity of organisms continuously evolving into a different variety ever since the origin of life had taken place. Diversity is present at different levels like genetic diversity, species diversity, and ecological diversity. Mango alone has around 10,000 varieties in India. This alone example indicates how large and diverse are the living organisms. Gaining knowledge about this large diversity is impossible without classifying them. Thus classification becomes an important step towards the study of different organisms found on the earth.
Biological Classification
The process of putting all the organisms in certain groups on the basis of certain similarities and differences is known as Classification
Various characteristics are taken into account in order to classify an organism. Some of them are-
The type of cell present whether the organism is having a eukaryotic cell or a prokaryotic cell.
The number of cells whether the organism is unicellular or multicellular.
Body organization whether the organization is cellular, tissue-level, or organ-level.
The nutrition of organisms whether it's autotrophic or heterotrophic.
Morphological features of the organisms.
Anatomical features of the organism etc.
All these features including many others are taken into consideration during the classification
Classification System
Various scientists have proposed their own model of classifying organisms. Some of these are given below.
Two Kingdom Classification
Carolus Linnaeus gave the 2-kingdom system of classification and divided all the organisms into two groups as Plantae and Animalia. This kind of classification brought all the organisms which had a cell wall together within their cell in one group called the Plantae and the rest all were placed in the other group known as Animalia.
Plantae comprises bacteria, fungi with plants. All were very different from each other but still were kept together under two-kingdom classification. There was no distinction between the prokaryotes as well as eukaryotes. Thus this system of classification was not right but surely helped in evolving a better classification system.
Five Kingdom Classification
R.H Whittaker proposed a five-kingdom classification. This classification is accepted and corrected worldwide. A number of criteria were considered for making this model like the cell type, cell number, cell organization, nutrition, etc.
It consists of 5 groups /kingdoms
Monera
Protista
Fungi
Plantae
Animalia
Characteristics of Five Kingdom
Kingdom Monera
This kingdom has organisms that are unicellular and have prokaryotic cell.
It includes bacteria, cyanobacteria, etc.
Their cell usually has a cell wall.
They can be autotrophic or heterotrophic.
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Kingdom Protista
This kingdom includes organisms that are also unicellular but have a eukaryotic cell.
They may be photosynthetic or heterotrophic.
They may possess structures like flagella and cilia.
Examples are amoeba, euglena, paramecium, etc.
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Kingdom Fungi
This is the first kingdom with multicellular organisms.
They exhibit a heterotrophic mode of nutrition more specifically saprotrophic mode of nutrition.
They have a eukaryotic cell with a cell wall that is made up of chitin.
Example - yeast, mushroom
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Kingdom Plantae
All organisms are eukaryotic and multicellular.
The body can be seen as differentiated into higher groups.
They are photosynthetic and exhibit an autotrophic mode of nutrition. Some members are partially heterotrophic.
Their cell has a cell wall made up of cellulose.
Examples- mango tree, red algae, etc.
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Kingdom Animalia
All members are eukaryotic and multicellular.
Their cells lack a cell wall.
They are heterotrophs.
Examples- lion, dog, fish, etc.
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Classification Hierarchy
The broadest group Kingdom is further divided into small groups to reach a point of maximum similarity in one group of organisms. Thus a hierarchy of classification is developed when the small groups are arranged from the lowest to the highest order. Each category in the hierarchy is known as Taxon.
Following is the Hierarchy of Classification:
Kingdom
Phylum / Division
Class
Order
Family
Genus
Species
Species are the basic unit of classification.
Classification and Evolution
Classification of organisms is related to evolution. Evolution is the change that takes more over the years in the body design of organisms for better survival. Charles Darwin first described the concept of evolution in his book ‘The Origin Of Species’ in 1859.
Lower organisms are the organisms that seem to have not changed over the years.
Higher organisms are relatively recent and have their particular body designs.
Diversity in Living Organisms is a fundamental topic introduced in students in higher and junior classes. It is a primary and essential topic of Study, for this one can easily follow Vedantu and know about interesting facts about Diversity.
Fun Facts
Yeast is the only unicellular fungus.
Lichens are organisms in which algae and fungi live together and exhibit symbiotic relationships.
FAQs on Diversity in Living Organisms: Meaning, Types & Classification
1. What is meant by 'diversity in living organisms'?
Diversity in living organisms, also known as biodiversity, refers to the vast variety of life forms found on Earth or in a specific habitat. It encompasses millions of species, from microscopic bacteria to large mammals, each with unique characteristics in terms of their structure, genetics, habitat, and mode of nutrition. This variety is the result of 3.5 billion years of evolution.
2. What is the main basis for the classification of living organisms?
The primary basis for classifying organisms is their shared characteristics, which reflect their evolutionary relationships. Biologists look for fundamental similarities and differences, starting with broad features and moving to more specific ones. Key characteristics include:
- Cell structure: Whether the cells are prokaryotic (lacking a defined nucleus) or eukaryotic (with a true nucleus).
- Body organisation: Whether the organism is unicellular (single-celled) or multicellular (composed of many cells).
- Mode of nutrition: Whether the organism is autotrophic (produces its own food, like plants) or heterotrophic (obtains food from other sources, like animals).
3. What is binomial nomenclature and what is its primary importance?
Binomial nomenclature is the universal scientific system for naming organisms, introduced by Carolus Linnaeus. Each species is given a unique two-part name: the first part is the Genus (always capitalised), and the second is the species (always lowercase). For instance, the scientific name for a tiger is *Panthera tigris*. Its primary importance is to provide a standardised, unambiguous name for every species, which avoids the confusion caused by common names that vary by language and region.
4. Can you explain the hierarchy of classification with an example?
The hierarchy of classification is a system where organisms are arranged into a series of successive levels or ranks. This Linnaean hierarchy, from the broadest to the most specific category, is:
- Kingdom
- Phylum (for animals) or Division (for plants)
- Class
- Order
- Family
- Genus
- Species
For example, the classification of a human is Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Order: Primates, Family: Hominidae, Genus: Homo, and Species: sapiens.
5. What are the key features of the five kingdoms proposed by R.H. Whittaker?
R.H. Whittaker's five-kingdom classification categorises organisms based on cell structure, body organisation, and mode of nutrition. The five kingdoms are:
- Monera: Includes unicellular prokaryotic organisms like bacteria and blue-green algae.
- Protista: Consists of unicellular eukaryotic organisms such as Amoeba and Paramecium.
- Fungi: Multicellular, eukaryotic, and saprophytic organisms with cell walls made of chitin. Examples include mushrooms and yeast.
- Plantae: Includes all multicellular, eukaryotic, and autotrophic organisms with cell walls made of cellulose, such as ferns, mosses, and flowering plants.
- Animalia: Consists of multicellular, eukaryotic, and heterotrophic organisms that lack a cell wall and are typically motile.
6. How are the concepts of classification and evolution interconnected?
Classification and evolution are deeply linked because modern classification systems aim to reflect the evolutionary relationships between organisms. Organisms placed in the same taxonomic group (like a family or order) are believed to share a more recent common ancestor with each other than with organisms in other groups. Therefore, the hierarchy of classification serves as a model of the evolutionary history of life, illustrating how different species have diverged from common ancestors over time.
7. Why are variations essential for the survival and adaptation of a species?
Variations, which are the small genetic differences among individuals within a species, are the fundamental raw material for evolution by natural selection. They are essential because they provide the potential for a species to adapt to changing environmental conditions. When the environment changes, individuals with variations that are advantageous in the new conditions are more likely to survive, reproduce, and pass those traits to the next generation, ensuring the long-term survival of the species.
8. What is the key difference between the Pteridophyta and Phanerogams groups in the plant kingdom?
The key difference lies in their reproductive structures. Pteridophytes (e.g., ferns) are non-flowering plants that reproduce through spores, and their reproductive organs are inconspicuous or hidden. For this reason, they are part of the Cryptogamae group. In contrast, Phanerogams (Gymnosperms and Angiosperms) are plants that have well-differentiated reproductive tissues and produce seeds to reproduce. Their name means 'visible reproduction'.
9. Why are organisms like viruses not included in Whittaker's five-kingdom classification?
Viruses are not included in the five-kingdom classification because they exist on the borderline between living and non-living entities. They lack a true cellular structure and cannot carry out metabolic processes on their own. Viruses are essentially inert crystalline structures outside a host but become active and reproduce by hijacking the host cell's machinery. This dependence on a host cell and their acellular nature means they do not fit the criteria for any of the five kingdoms, which are all based on cellular organisms.
