Short Answer
Living organisms show certain special features that distinguish them from non-living things. These features are called characteristics of living organisms. All plants, animals, and microorganisms share some basic life activities that prove they are alive.
The main characteristics of living organisms include growth, nutrition, respiration, excretion, reproduction, movement, response to stimuli, and adaptation. These characteristics help organisms survive, maintain life processes, and continue life on Earth.
Detailed Explanation :
Main Characteristics of Living Organisms
Living organisms are different from non-living things because they perform specific life activities. These activities are essential for survival and continuation of life. Biology studies these characteristics to identify and understand living beings. The main characteristics of living organisms are explained below in a simple and clear way.
Growth
Growth is one of the most important characteristics of living organisms. It refers to a permanent increase in size, mass, and complexity of the body. Living organisms grow by increasing the number and size of their cells. For example, a small plant grows into a big tree, and a baby grows into an adult.
Growth in living organisms occurs from inside due to cell division. Non-living things like mountains or crystals may increase in size, but their growth is external and not due to life processes. Therefore, true growth is a characteristic only of living organisms.
Nutrition
Nutrition is the process by which living organisms obtain food and use it for energy, growth, repair, and maintenance of the body. All living organisms need food to survive. Plants prepare their own food through photosynthesis and are called autotrophs.
Animals and humans depend on plants or other animals for food and are called heterotrophs. Nutrition provides energy required for all life activities, making it an essential characteristic of living organisms.
Respiration
Respiration is the process of breaking down food to release energy. Living organisms need energy to perform activities like movement, growth, repair, and reproduction. Respiration can be aerobic, using oxygen, or anaerobic, without oxygen.
Plants, animals, and microorganisms all respire in different ways. Even plants respire all the time, though it is not easily visible. Non-living things do not respire, which makes respiration a key characteristic of life.
Excretion
Excretion is the process of removing waste materials produced during life processes. Waste substances like carbon dioxide, urea, and excess water can be harmful if they accumulate in the body.
Living organisms have different methods of excretion. Humans use kidneys, lungs, and skin for excretion. Plants remove waste through stomata, leaves, and storage tissues. Excretion helps maintain internal balance, which is necessary for survival.
Reproduction
Reproduction is the ability of living organisms to produce new individuals of their own kind. It ensures the continuity of life on Earth. Reproduction can be sexual or asexual.
Animals usually reproduce sexually, while plants and microorganisms may reproduce sexually or asexually. Although reproduction is not necessary for the survival of an individual, it is essential for the survival of the species. Non-living things cannot reproduce.
Movement
Movement is another important characteristic of living organisms. Animals move from one place to another in search of food, shelter, and safety. Even plants show movement, such as the opening and closing of flowers and bending toward light.
Movement in living organisms is due to internal energy and life processes. Non-living things move only when an external force is applied, like wind or water.
Response to Stimuli
Living organisms have the ability to respond to changes in their surroundings, called stimuli. Stimuli include light, heat, sound, touch, and chemicals. For example, humans pull their hand away from a hot object, and plants bend toward sunlight.
This sensitivity helps organisms protect themselves and adapt to their environment. Non-living things do not show such responses.
Adaptation
Adaptation is the ability of living organisms to adjust to their environment for survival. Adaptations may be structural, functional, or behavioral. For example, camels have long legs and humps to survive in deserts.
Adaptation helps organisms live successfully in different environments. This characteristic shows that living organisms can change over time to suit their surroundings.
Cellular Organization
All living organisms are made up of cells. Cells are the basic structural and functional units of life. Some organisms are unicellular, like bacteria, while others are multicellular, like plants and animals.
Non-living things are not made of cells. This cellular structure is a defining characteristic of living organisms.
Conclusion
Living organisms show many unique characteristics such as growth, nutrition, respiration, excretion, reproduction, movement, response to stimuli, adaptation, and cellular organization. These characteristics help distinguish living beings from non-living things. By studying these features, biology helps us understand life and the processes that keep living organisms alive and functioning.