Which of the following is NOT one of the seven abiotic factors of an ecosystem?

The correct response identifies an important distinction in understanding abiotic factors within an ecosystem. Abiotic factors refer to the non-living chemical and physical components of an environment that can influence living organisms.

Temperature is considered an abiotic factor because it affects metabolic processes and can influence species distribution. Oxygen is also vital as it is required for respiration by many organisms, and salinity, the concentration of salts in water, is a critical factor affecting aquatic ecosystems and the types of life that can thrive in those environments.

Carbon dioxide, while often regarded as a minor component in the discussion of abiotic factors, plays a crucial role as a gas in the atmosphere, contributing to the greenhouse effect and being a key reactant in photosynthesis. However, in many contexts discussing abiotic factors, carbon dioxide is often grouped with the larger category of atmospheric gases rather than being listed independently as a significant abiotic component like temperature or salinity.

Therefore, understanding the role and classification of carbon dioxide can clarify why it may not always appear in lists of abiotic factors when comparing other elements that have more direct, physical interactions with ecosystems.