Scientists say that photosynthesis and cellular respiration create a cycle that is essential to almost all life on Earth. Use your knowledge of these processes to explain how an oil spill that kills a large percentage of the photosynthetic organisms living in the ocean could affect humans.

Explanation:

An oil spill is a catastrophic event in the environment. It can negatively affect both plants and wildlife while causing human suffering and economic losses. An oil spill needn't be on the scale of the Exxon Valdez or Deepwater Horizon disasters. The U.S. Environmental Protection Agency (EPA) estimates that 200 million gallons of used oil are disposed of improperly each year.

Spilled oil floats on the surface of the water, blocking the sunlight, from reaching the plants within the body of water. Spilled oil may also directly coat the leaves of plants -- where most of the work of photosynthesis occurs -- reducing or blocking out sunlight. Without sunlight, plants lack the energy needed to undergo photosynthesis.

An oil spill can impact photosynthesis by reducing water quality. Not only does the presence of oil directly poison the water, but the spill can kill sea life, birdlife and other wildlife that uses an aquatic habitat. A large die-off can increase bacteria levels and lower the pH of a body of water. The reduction in water quality can stress plants, essentially halting photosynthesis.