All organisms, from primitive prokaryotes to most advanced and complex eukaryotes, are able to sense and respond to environmental factors. The stimuli are perceived by sense organs in higher animals through sensory receptors in the eyes, ears, nose etc. Plants do not possess such sense organs. However, they do respond to external factors such as light, water, temperature, pollutants, other organisms, etc. Human beings have an additional facility of self consciousness (awareness of self). Consciousness and response to stimuli are said to be defining properties of living organisms

Introduction:
Living organisms can be distinguished from non-living structures based on several characteristics. These characteristics include reproduction, growth and movement, interaction with the environment, and responsiveness. Let's explore each of these characteristics in detail.

Reproduction:
One of the key characteristics of living organisms is the ability to reproduce. Reproduction is the process by which living organisms produce offspring of their own kind, ensuring the continuation of their species. Non-living structures, on the other hand, cannot reproduce. They do not possess the ability to create copies of themselves or generate new individuals.

Growth and Movement:
Living organisms exhibit growth and movement, which are essential for their survival and adaptation. Growth refers to an increase in size or number of cells in an organism over time. It is a characteristic of living organisms that allows them to develop and mature. Non-living structures, on the other hand, do not grow or change in size or complexity.

Movement is another vital characteristic of living organisms. Most living organisms can move, either by locomotion (self-movement) or by movement of internal structures (such as organelles within cells). Non-living structures, such as rocks or buildings, do not have the ability to move on their own.

Interaction with the Environment:
Living organisms interact with their environment, responding to various stimuli and acquiring resources necessary for their survival. They can obtain energy, nutrients, and water from the environment and eliminate waste products. Living organisms can also respond to changes in their surroundings, such as temperature or light.

Non-living structures, in contrast, do not interact with the environment or respond to stimuli. They cannot acquire resources or eliminate waste independently. They remain passive and do not exhibit any form of interaction or response.

Responsiveness:
Responsiveness is the ability of living organisms to detect and respond to changes in their environment. This characteristic allows organisms to adapt to their surroundings and ensure their survival. Living organisms can respond to stimuli such as light, sound, temperature, or touch.

Non-living structures lack responsiveness. They do not possess the ability to detect or respond to stimuli in their environment. They remain unchanged and unaffected by external factors.

Conclusion:
Living organisms can be distinguished from non-living structures based on several characteristics, including reproduction, growth and movement, interaction with the environment, and responsiveness. These characteristics are fundamental to the definition of life and differentiate living organisms from non-living structures.