The fundamental distinction between living and nonliving things lies in the presence of certain life processes and characteristics. Based on common biological understanding, all living things breathe, eat, grow, move, reproduce and have senses. In contrast, non-living things do not eat, grow, breathe, move and reproduce. They do not have senses.
Understanding this difference is crucial for classifying the diverse world around us. Here's a breakdown of the key characteristics that differentiate living organisms from inanimate objects:
Key Differences Between Living and Nonliving Things
| Characteristic | Living Things | Non-Living Things |
|---|---|---|
| Respiration/Breathing | Yes, they breathe to obtain energy. | No, they do not breathe. |
| Nutrition/Eating | Yes, they require food or nutrients for energy and growth. | No, they do not eat or require nutrients. |
| Growth | Yes, they grow and develop over time. | No, they do not grow naturally. (Growth in non-living things, like crystals, is by external accretion, not internal development). |
| Movement | Yes, they show movement (either self-initiated or through growth). | No, they do not move on their own. (Movement needs external force). |
| Reproduction | Yes, they can reproduce to create offspring. | No, they cannot reproduce. |
| Response to Stimuli | Yes, they sense and respond to changes in their environment. | No, they do not sense or respond to stimuli. |
| Cellular Organization | Yes, they are made up of one or more cells. | No, they are not made of cells. |
| Metabolism | Yes, they perform metabolic processes (chemical reactions for life). | No, they do not perform metabolism. |
| Excretion | Yes, they excrete waste products. | No, they do not excrete. |
Let's elaborate on some of these points:
Respiration
- Living Things: Obtain energy from food through processes like cellular respiration, which often involves breathing (taking in oxygen and releasing carbon dioxide). This energy is vital for performing all life activities.
- Non-Living Things: Do not respire or breathe to gain energy.
Growth and Development
- Living Things: Increase in size and complexity through internal biological processes. A seedling grows into a plant; a baby grows into an adult. This growth is intrinsic.
- Non-Living Things: Do not grow from within. If they increase in size (like a salt crystal), it's usually by the addition of external material.
Movement
- Living Things: Exhibit movement, which can be as simple as the flow of cytoplasm within a cell, the bending of a plant towards light, or the walking/flying of animals. This movement can be for various purposes like finding food, escaping predators, or reproduction.
- Non-Living Things: Do not move unless acted upon by an external force (e.g., a ball rolls when pushed).
Reproduction
- Living Things: Have the ability to produce new individuals of their own kind, ensuring the continuation of their species. This can be sexual or asexual.
- Non-Living Things: Lack the biological mechanisms to create replicas of themselves.
Response to Stimuli (Senses)
- Living Things: Possess senses or mechanisms to detect changes in their environment (stimuli) such as light, temperature, sound, touch, or chemicals. They react to these stimuli, which helps them survive.
- Non-Living Things: Do not have senses and cannot perceive or respond to stimuli in a biological manner.
Examples
- Living Things: Plants, animals, bacteria, fungi, humans.
- Non-Living Things: Rocks, water, air, sunlight, cars, books, tables.
While it might seem straightforward, the definition of "living" can become complex at the boundaries (like viruses, which show some life characteristics only within a host cell). However, for Class 11, focusing on the key properties mentioned above, based on observable processes like metabolism, growth, reproduction, response, and organization, provides a solid foundation.
