What type of organism may use inorganic chemicals for both energy and a carbon source? a. A photoautotroph c. A chemoautotroph b. A photoheterotroph d. A chemoheterotroph
The Correct Answer and Explanation is :
The correct answer is c. A chemoautotroph.
Explanation:
Chemoautotrophs are organisms that can use inorganic chemicals as both a source of energy and a source of carbon. These organisms do not rely on sunlight (as photoautotrophs do) to produce energy; instead, they use chemical reactions involving inorganic compounds such as hydrogen sulfide (H₂S), ammonia (NH₃), or ferrous iron (Fe²⁺) to generate energy. This process is known as chemosynthesis. The energy obtained from these inorganic chemicals is then used to convert carbon dioxide (CO₂) into organic compounds, a process called carbon fixation, which provides the necessary carbon source for the organism’s growth and metabolism.
Some common examples of chemoautotrophs include:
- Sulfur bacteria (which use hydrogen sulfide as an energy source)
- Nitrifying bacteria (which oxidize ammonia or nitrites)
- Iron bacteria (which use ferrous iron as an energy source)
In contrast:
- Photoautotrophs (like plants and algae) use sunlight as the primary source of energy and carbon dioxide as their carbon source.
- Chemoheterotrophs require organic compounds (such as sugars, lipids, and proteins) both as a source of energy and a carbon source, similar to the nutritional needs of animals and fungi.
- Photoheterotrophs use sunlight for energy but require organic compounds for carbon, which is different from the chemoautotrophs’ reliance on inorganic sources.
Chemoautotrophs are often found in extreme environments, such as deep-sea vents, hot springs, or soil environments, where sunlight is not available, but inorganic chemicals can still serve as energy sources.
Let me generate an image to illustrate this process.
Here is an illustration of a deep-sea vent ecosystem, where chemoautotrophic bacteria use hydrogen sulfide to produce energy and fix carbon dioxide. It shows how these organisms thrive in environments where inorganic chemicals are available, supporting their chemosynthetic processes.
