The image shows a section through part of a peat bog. Layer B contains the dead remains of plants, has a low pH, and contains very little oxygen.

Explain why most of the dead remains of plants in layer B do not decay.

Decomposition is the process by which organic substances are broken down into simpler organic or inorganic matter. This process is primarily carried out by decomposers, which are microorganisms such as bacteria and fungi. Most decomposers perform aerobic respiration, which requires oxygen to release energy from the organic matter. In the waterlogged conditions of a peat bog (Layer B), there is very little oxygen available (anaerobic conditions). This severely limits the activity of aerobic decomposers. Additionally, the low pH (acidic conditions) is outside the optimal range for the enzymes of many decomposers, causing them to denature (change shape) and become ineffective. The combination of anaerobic and acidic conditions prevents decay.