In the core sample collected from Yellowstone, which layer is the cyanobacteria?

In the core sample collected from Yellowstone, which layer is the cyanobacteria?

• A. The greenish layer on top
• B. The bottom dark layer
• C. The middle reddish layer
• D. The outermost crust

Answer: (A)

Cyanobacteria are photosynthetic organisms that need light, so they live where light can reach in a sediment or rock core. That means the uppermost layer, which often appears green due to the chlorophyll in cyanobacteria. The bottom dark layer tends to be shielded from light and more mineral-rich, so it’s not where photosynthetic microbes dominate. The middle reddish layer and the outermost crust are typically more influenced by mineral processes or different microbial communities, not the green, chlorophyll-bearing cyanobacteria. So the cyanobacteria are in the greenish, uppermost layer.

Cyanobacteria are photosynthetic organisms that need light, so they live where light can reach in a sediment or rock core. That means the uppermost layer, which often appears green due to the chlorophyll in cyanobacteria. The bottom dark layer tends to be shielded from light and more mineral-rich, so it’s not where photosynthetic microbes dominate. The middle reddish layer and the outermost crust are typically more influenced by mineral processes or different microbial communities, not the green, chlorophyll-bearing cyanobacteria. So the cyanobacteria are in the greenish, uppermost layer.