OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is the end product of DOM breakdown that is used by fungi for growth?

1. Large, complex sugars

2. Gases eliminated into the atmosphere

3. Small, soluble molecules absorbed by fungal threads

4. Solid waste that bacteria can consume

The correct answer is: Small, soluble molecules absorbed by fungal threads

The end product of decomposed organic matter (DOM) breakdown that is utilized by fungi for growth consists of small, soluble molecules that can be readily absorbed by their hyphal threads. This process begins with fungi breaking down complex organic materials in the environment, which includes dead plant and animal matter. Through their enzymatic activity, fungi convert these larger compounds into smaller, soluble forms, such as sugars and amino acids, that can easily enter their cells. This ability to digest organic material makes fungi key decomposers in ecosystems, playing a critical role in nutrient recycling. Small, soluble molecules provide the necessary nutrients that fungi use for energy, growth, and reproduction. In contrast to the other options, large, complex sugars would not be directly absorbed and utilized, gases eliminated would not serve as a growth nutrient, and solid waste is not the primary focus of fungal nutrition. By targeting small, soluble molecules, fungi efficiently harness energy from their environment, facilitating a symbiotic balance within ecosystems.