Ontario Grade 9 Science Class Practice Exam 2025 - Free Grade 9 Science Practice Questions and Study Guide

A living organism is defined by a set of characteristics that differentiate it from non-living things. The presence of the traits mentioned, such as the ability to grow, reproduce, respond to stimuli, metabolize energy, and adapt to the environment, collectively categorizes an entity as a living organism.

Growth refers to the increase in size and mass, while reproduction is the ability to produce new individuals. The ability to respond to stimuli indicates that organisms can react to changes in their environment, which is crucial for survival. Metabolism encompasses all the chemical reactions that occur within an organism to maintain life, including how it obtains and uses energy. Adaptation refers to the physiological or behavioral changes that occur over generations, allowing organisms to survive in their respective environments.

The other choices do not capture the defining characteristics of life. For example, existing only for a short period does not inherently imply that something is alive; many living organisms can live for extended periods. The idea of a fixed shape and size disregards the variability and dynamic nature of living organisms, as they can change due to growth or environmental factors. Lastly, suggesting that an organism requires artificial means to function contradicts the fundamental characteristics of living organisms, which can sustain themselves through natural processes.