Florida Teacher Certification Examinations (FTCE) Subject Area Practice Test

Why is a crystal considered to be a non-living organism?

1. It does not grow in size

2. It does not undergo reproduction

3. It does not respond to stimuli

4. It does not perform photosynthesis

The correct answer is: It does not respond to stimuli

A crystal is considered a non-living organism primarily because it does not respond to stimuli. Unlike living organisms, which can react to environmental changes and stimuli in various ways, crystals are purely physical structures formed by the orderly arrangement of atoms or molecules. This lack of responsiveness is a key characteristic that distinguishes non-living things from living organisms. In contrast, living organisms engage with their surroundings, adapting to changes, moving, or modifying behavior in response to external factors such as light, heat, or pressure. For instance, plants move their leaves toward the light source, and animals flee from danger, which illustrates how living entities interact with their environment. The other options touch upon aspects of life but do not define living organisms as clearly as the concept of responsiveness. While crystals do not grow in the biological sense or reproduce, they can grow in size under appropriate conditions through processes like crystallization, which is a physical change rather than a biological one. Similarly, reproduction is a trait of life but does not encompass the full definition. Performing photosynthesis is specific to certain living organisms (like plants) and not a universal characteristic of all life forms. Thus, the defining characteristic remains the inability of crystals to respond to stimuli, cementing their classification as non-living matter