In the context of photosynthesis and fossil formation, how do organisms form carbon films?

• A. By undergoing rapid decomposition in the presence of oxygen, resulting in a carbon-rich film
• B. By being buried under sediment, where heat and pressure remove gases and liquids, leaving a thin layer of carbon residue
• C. By photosynthesizing and storing excess glucose as a carbon film on their cell walls
• D. By directly absorbing carbon dioxide from the atmosphere and depositing it as a solid film on their surfaces

Answer: (B)

Verified step by step guidance

1. Understand the concept of carbon films: Carbon films are thin layers of carbon residue left behind when organic material undergoes specific processes. These films are often found in fossils and provide detailed impressions of the organism's structure.
2. Recognize the conditions required for carbon film formation: Organisms must be buried under sediment, which protects them from rapid decomposition. This burial creates an environment where heat and pressure can act on the organic material.
3. Explain the role of heat and pressure: Over time, heat and pressure remove volatile components such as gases and liquids from the buried organism. This process concentrates the carbon content, leaving behind a thin carbon-rich layer.
4. Clarify why oxygen presence prevents carbon film formation: If decomposition occurs in the presence of oxygen, the organic material breaks down completely, leaving no residue. This is why burial under sediment is crucial to isolate the organism from oxygen.
5. Eliminate incorrect options: Photosynthesis and glucose storage do not lead to carbon film formation, nor does direct absorption of carbon dioxide. The correct process involves burial under sediment, heat, and pressure.