Microorganisms are involved in each of the following processes except:

• A. Decomposition of organic matter
• B. Formation of igneous rocks
• C. Photosynthesis in aquatic environments
• D. Nitrogen fixation in soil

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of microorganisms in natural processes. Microorganisms are living organisms such as bacteria, fungi, and algae that play crucial roles in various biochemical cycles and environmental functions.
2. Step 2: Analyze each process listed in the problem to determine if microorganisms are involved:
3. - Decomposition of organic matter: Microorganisms like bacteria and fungi break down dead organic material, recycling nutrients back into the ecosystem.
4. - Photosynthesis in aquatic environments: Certain microorganisms, such as cyanobacteria and algae, perform photosynthesis, producing oxygen and organic compounds.
5. - Nitrogen fixation in soil: Specific bacteria convert atmospheric nitrogen (N₂) into forms usable by plants, a vital step in the nitrogen cycle.
6. Step 3: Consider the process of formation of igneous rocks. This is a geological process involving the cooling and solidification of molten magma or lava, which is abiotic and does not involve living organisms.
7. Step 4: Conclude that since the formation of igneous rocks is a non-biological, geological process, microorganisms are not involved in this process, unlike the other options.