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

What role do photosynthesizing organisms play in the food chain?

1. They are primary consumers

2. They serve as decomposers

3. They form the base of the food chain

4. They are secondary consumers

The correct answer is: They form the base of the food chain

Photosynthesizing organisms, such as plants and certain algae, are fundamental to the food chain as they are the primary producers. This means they can convert light energy from the sun into chemical energy through the process of photosynthesis, creating organic compounds from carbon dioxide and water. These organisms form the base of the food chain because they provide the essential energy source for all other consumers, including herbivores (primary consumers) and carnivores (secondary consumers). Without photosynthesizers, there would be no primary production of energy, making it impossible for the food chain to function effectively. Hence, their role as the foundation of the food chain is vital to sustaining ecosystems and supporting all life forms that depend on them for energy.