Without photosynthesis, the earliest cells most likely absorbed nutrients that floated in the organic soup that surrounded them. After hundreds of millions of years, these nutrients would have become less abundant. Sometime around 3 billion years ago, photosynthesis began. Photosynthesis allowed organisms to use sunlight and inorganic molecules to create chemical energy that they could use for food. They no longer needed to rely on nutrients floating in their environment. Photosynthesizing organisms could also become food for other organisms. A byproduct of photosynthesis is the... Show more Without photosynthesis, the earliest cells most likely absorbed nutrients that floated in the organic soup that surrounded them. After hundreds of millions of years, these nutrients would have become less abundant. Sometime around 3 billion years ago, photosynthesis began. Photosynthesis allowed organisms to use sunlight and inorganic molecules to create chemical energy that they could use for food. They no longer needed to rely on nutrients floating in their environment. Photosynthesizing organisms could also become food for other organisms. A byproduct of photosynthesis is the production of oxygen. After photosynthesis evolved, oxygen was soon present in the atmosphere in far greater concentrations than ever before. The addition of oxygen from photosynthesis created Earth’s third atmosphere. This event is sometimes called the oxygen catastrophe because so many organisms died out. For organisms adapted to an oxygen-free environment, oxygen was toxic. The event is also called the great oxygenation event because it was a great opportunity for other organisms. The few organisms that survived developed a vital use for oxygen, cellular respiration. This is the process by which cells use oxygen to obtain energy from organic molecules. These organisms were able to flourish in the new atmosphere. The addition of oxygen to the atmosphere was important to living things for another reason as well. With oxygen in the atmosphere, the ozone layer could develop. The ozone layer protected Earth’s surface from harmful ultraviolet light radiating from the sun. This allowed more complex life forms to evolve. Show less
Without photosynthesis, the earliest cells most likely absorbed nutrients that floated in the organic soup that surrounded them. After hundreds of millions of years, these nutrients would have become less abundant. Sometime around 3 billion years ago, photosynthesis began. Photosynthesis allowed organisms to use sunlight and inorganic molecules to create chemical energy that they could use for food. They no longer needed to rely on nutrients floating in their environment. Photosynthesizing organisms could also become food for other organisms. A byproduct of photosynthesis is the production of oxygen. After photosynthesis evolved, oxygen was soon present in the atmosphere in far greater concentrations than ever before. The addition of oxygen from photosynthesis created Earth’s third atmosphere. This event is sometimes called the oxygen catastrophe because so many organisms died out. For organisms adapted to an oxygen-free environment, oxygen was toxic. The event is also called the great oxygenation event because it was a great opportunity for other organisms. The few organisms that survived developed a vital use for oxygen, cellular respiration. This is the process by which cells use oxygen to obtain energy from organic molecules. These organisms were able to flourish in the new atmosphere. The addition of oxygen to the atmosphere was important to living things for another reason as well. With oxygen in the atmosphere, the ozone layer could develop. The ozone layer protected Earth’s surface from harmful ultraviolet light radiating from the sun. This allowed more complex life forms to evolve.
Join 4M+ learners. Unlock unlimited quizzes, wrong-answer tracking, flashcards + reminders, study guides, and 1-on-1 challenges.