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

Which of the following components is not typically found in soil?

1. Sand

2. Seaweed

3. Animal dung

4. Clay

The correct answer is: Seaweed

Soil is primarily composed of mineral particles, organic matter, water, and air. Common components include sand, clay, and organic materials such as animal dung, which contributes nutrients to the soil. Sand and clay are essential for determining soil texture and drainage properties, while animal dung enriches the soil with organic matter that supports microbial life and plant growth. Seaweed, while a rich source of nutrients, is not a typical component of soil. It is generally found in marine environments and can be applied as mulch or fertilization in gardening, but it is not part of the natural soil composition. Therefore, the presence of seaweed in this context distinguishes it from the other components that are commonly found and integral to soil structure and fertility.