Which set of characteristics best describes living organisms?

• A. Growth, reproduction, response to stimulus, breakdown food molecules, production of waste products, composed of cells (unicellular or multicellular).
• B. Movement, reproduction, photosynthesis, and absence of waste production.
• C. Genetic material only and lack of cells.
• D. Inability to grow or respond to the environment.

Answer: (A)

Living organisms are defined by a set of features that together indicate life: they are organized at the cellular level, they grow, they reproduce, they respond to environmental stimuli, and they carry out metabolism to obtain and use energy, which also results in waste production. The option that includes growth, reproduction, response to stimulus, breakdown of nutrients for energy, waste production, and cellular organization (unicellular or multicellular) best captures what science uses to define living things. These elements cover both the ability to change and adapt, and the essential biological processes that sustain life.

The other choices fall short because they omit universal aspects of life. Not all living things perform photosynthesis, and movement is not a universal trait. Having only genetic material without cells would not support metabolic activities or growth. And the inability to grow or respond to the environment contradicts what living organisms routinely do.