A Level Biology Practice Exam

What can affect the surface area to volume ratio of an organism?

1. The age of the organism

2. The shape and size of the organism

3. The type of nutrients consumed

4. The number of cell types in the organism

The correct answer is: The shape and size of the organism

The surface area to volume ratio is a crucial concept in biology, particularly in understanding how organisms exchange materials with their environment. As an organism's size increases, its volume increases faster than its surface area, leading to a decrease in this ratio. Therefore, the shape and size of an organism significantly influence this ratio. For example, elongated or flattened shapes can maximize surface area relative to volume, facilitating more effective absorption of nutrients or release of waste products. This is particularly relevant for processes such as gas exchange in respiration and nutrient uptake. Conversely, more compact shapes may have a higher volume compared to surface area, making it less efficient for these vital processes. Other factors, like age, type of nutrients, or the number of cell types, do not directly relate to the fundamental geometric relationship that governs surface area and volume. Thus, the shape and size of the organism are key determinants in understanding the implications of the surface area to volume ratio for metabolic processes and overall function.