Characteristics of Living Organisms: Growth, Reproduction & Metabolism
Characteristics of Living Organisms: Growth, Reproduction, Metabolism & More
Characteristics of Living Organisms are the fundamental features that distinguish living organisms from non-living objects. Important characteristics include growth, reproduction, metabolism, consciousness, cellular organisation and the ability to respond to the environment. These concepts are important for NCERT Biology, NEET and CBSE examinations.
What Is Biology?
The term Biology refers to the scientific study of life and living organisms.
- Bios = Life
- Logos = To study
The term Biology was coined independently by Lamarck and Treviranus.
Father of Biology
Aristotle is traditionally regarded as the Father of Biology and Zoology.
Branches of Biology
Botany
Botany is the branch of Biology concerned with the study of plants.
- Father of Botany: Theophrastus
- Father of Indian Botany: William Roxburgh
Zoology
Zoology is the branch of Biology concerned with the study of animals.
- Father of Zoology: Aristotle
Modern Taxonomy
Carolus Linnaeus is widely known as the Father of Modern Taxonomy and is closely associated with the development of systematic classification and binomial nomenclature.
Important Books Related to Taxonomy
1. Historia Plantarum
- Written by Theophrastus.
- It is one of the earliest important works on plants.
2. Genera Plantarum
- Associated with Carolus Linnaeus.
- It contributed significantly to systematic plant classification.
3. Systema Naturae
- Written by Carolus Linnaeus.
- The 10th edition, published in 1758, is particularly important in zoological nomenclature.
4. Species Plantarum
- Written by Carolus Linnaeus.
- Published in 1753.
- It is an important work in the history of binomial nomenclature.
Example of binomial nomenclature: Homo sapiens
What Is Life?
Life can be described as the state or property of organisms that enables them to maintain their organisation, carry out metabolic activities, respond to their surroundings and reproduce.
From a biological perspective, living organisms possess a highly organised system of molecules and cells in which numerous chemical reactions occur to maintain life processes.
Characteristics of Living Organisms
The major characteristics of living organisms include:
- Growth
- Reproduction
- Metabolism
- Consciousness
- Cellular organisation
1. Growth
Growth refers to an increase in mass, size, volume, number of cells or amount of protoplasm of an organism.
In living organisms, growth is generally associated with an increase in cellular mass and/or cell number.
Growth in Living Organisms
Growth in living organisms is generally a permanent and irreversible change associated with the formation of new cellular material.
A simple relationship can be expressed as:
Growth results from successful metabolic activity and cellular processes.
Increase in Number of Cells
The number of cells in a multicellular organism increases mainly through cell division.
Increase in Mass
Increase in mass can occur through:
- Intrinsic growth – growth occurring from within, characteristic of living organisms.
- Extrinsic growth – increase in size or mass due to addition of material from outside, as seen in some non-living objects.
2. Reproduction
Reproduction is the biological process by which organisms produce new individuals of their own kind.
Reproduction is an important characteristic of living organisms, but it is not considered an absolute defining feature of life.
This is because some living organisms, such as mules and sterile worker bees, are unable to reproduce.
Types of Reproduction
Asexual Reproduction
Asexual reproduction involves reproduction without the fusion of male and female gametes. It is commonly seen in unicellular organisms and some multicellular organisms.
Examples of asexual reproduction include:
- Fission
- Budding
Sexual Reproduction
Sexual reproduction generally involves the formation of male and female gametes followed by their fusion.
The fusion of gametes is called syngamy and produces a zygote.
3. Metabolism
Metabolism refers to the sum total of all chemical reactions occurring within a living organism or cell.
Metabolic reactions are essential for maintaining life and performing various cellular functions.
Two Major Components of Metabolism
- Anabolism: Constructive metabolic reactions in which complex molecules are synthesised.
- Catabolism: Breakdown reactions in which complex molecules are converted into simpler molecules.
Metabolism is one of the most important and fundamental characteristics of living organisms.
Metabolism in Vitro
Some metabolic reactions can be demonstrated in vitro, meaning outside the living organism, under suitable laboratory conditions.
4. Consciousness
Consciousness refers to the ability of an organism to sense and respond to changes in its surroundings.
Living organisms continuously interact with their environment and respond to different physical and chemical stimuli.
Human Consciousness
Self-consciousness is a particularly advanced characteristic associated with human beings.
5. Cellular Organisation
All living organisms possess a definite level of cellular organisation.
The cell is considered the basic structural and functional unit of life. Organisms may be:
- Unicellular – consisting of a single cell.
- Multicellular – consisting of many cells organised into tissues, organs and organ systems.
Cellular organisation is therefore a fundamental characteristic of living organisms.
Why Is Metabolism Important in Living Organisms?
Metabolism provides the chemical basis for life. Through metabolic reactions, organisms:
- Obtain and utilise energy.
- Synthesise essential biomolecules.
- Break down nutrients.
- Maintain cellular structures.
- Support growth and reproduction.
- Respond to environmental conditions.
Biological Diversity
Living organisms show enormous diversity in their:
- Structure
- Size
- Cellular organisation
- Metabolism
- Reproduction
- Habitat
- Adaptations
This enormous diversity is the basis for the scientific study and classification of living organisms.
Quick Revision Table
| Characteristic | Key Point |
|---|---|
| Growth | Increase in mass, size, volume or cell number |
| Reproduction | Production of new individuals |
| Metabolism | Sum total of chemical reactions |
| Consciousness | Ability to sense and respond to surroundings |
| Cellular Organisation | Definite organisation based on cells |
NEET Biology Important Points
- Father of Biology: Aristotle
- Father of Botany: Theophrastus
- Father of Zoology: Aristotle
- Father of Modern Taxonomy: Carolus Linnaeus
- Growth: Important characteristic but not an absolute defining feature.
- Reproduction: Important characteristic but not an absolute defining feature.
- Metabolism: A defining feature of living organisms.
- Consciousness: Ability to sense and respond to environmental stimuli.
- Cellular organisation: Fundamental feature of living organisms.
Frequently Asked Questions
What are the main characteristics of living organisms?
The major characteristics include growth, reproduction, metabolism, consciousness and cellular organisation.
Why is reproduction not considered a defining characteristic of life?
Because some living organisms, such as mules and sterile worker bees, cannot reproduce.
Why is metabolism considered a defining characteristic of life?
Metabolism represents the totality of chemical reactions that occur in living systems and is essential for maintaining life.
What is the difference between anabolism and catabolism?
Anabolism involves the synthesis of complex molecules, whereas catabolism involves the breakdown of complex molecules into simpler substances.
What is cellular organisation?
Cellular organisation refers to the organised cellular structure of living organisms, with the cell serving as the basic structural and functional unit of life.
Conclusion
The characteristics of living organisms provide the foundation for understanding Biology. Growth, reproduction, metabolism, consciousness and cellular organisation help us understand how living systems differ from non-living matter. For NEET and CBSE students, these concepts should be studied carefully because they form the foundation of several important chapters in Biology.
