An ecosystem is unlikely to be limited by the supply of _____ because it is obtained from the air.

• A. potassium
• B. calcium
• C. carbon dioxide
• D. phosphorus

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of limiting factors in an ecosystem. Limiting factors are resources or environmental conditions that restrict the growth, abundance, or distribution of organisms in an ecosystem. These factors can include nutrients, water, light, or other essential elements.
2. Step 2: Recognize that carbon dioxide (CO₂) is a key component of photosynthesis, the process by which plants convert light energy into chemical energy. CO₂ is obtained from the air and is generally abundant in the atmosphere, making it unlikely to be a limiting factor in most ecosystems.
3. Step 3: Compare carbon dioxide with the other options provided: potassium, calcium, and phosphorus. These elements are essential nutrients for plants and other organisms, but they are typically obtained from the soil and can become limiting factors if their availability is low.
4. Step 4: Understand that potassium, calcium, and phosphorus are macronutrients required for various biological processes, such as enzyme activation, cell wall structure, and energy transfer. Unlike carbon dioxide, these nutrients are not sourced from the air and can be depleted in the soil, limiting ecosystem productivity.
5. Step 5: Conclude that carbon dioxide is unlikely to be a limiting factor in an ecosystem because it is readily available from the air, whereas potassium, calcium, and phosphorus are obtained from the soil and can become limiting factors if their supply is insufficient.