PADI Divemaster Certification Practice Exam

What is one main way the ocean is vital to life on Earth?

1. It serves as a transport medium for debris

2. It produces a majority of the food consumed

3. It generates oxygen through phytoplankton

4. It creates weather patterns

The correct answer is: It generates oxygen through phytoplankton

The ocean plays a crucial role in generating oxygen through phytoplankton, which are microscopic plants found in ocean waters. These organisms use sunlight to photosynthesize, a process during which they convert carbon dioxide and water into glucose and oxygen. It is estimated that phytoplankton are responsible for producing about 50-70% of the oxygen in our atmosphere, making them essential for supporting life on Earth. This oxygen production is vital for both marine and terrestrial life, as it contributes significantly to the air that all aerobic organisms depend on for survival. The presence of phytoplankton in the oceans also supports a larger food web, as they serve as the primary producers at the base of the marine food chain, affecting nutrient cycles and fish populations. While the ocean does indeed serve as a transport medium for debris, contribute to weather patterns, and support the food consumed, the generation of oxygen through phytoplankton is a fundamental process that directly impacts the sustainability of life on our planet.