S9 Unit 1 Worksheets

1. The document discusses key events in the early history of life on Earth based on an events diagram. 2. It shows that the Earth formed 4600 million years ago, the first living organisms appeared 4000 million years ago, and organisms capable of photosynthesis first evolved 3000 million years ago. 3. The rise of oxygen in the atmosphere around 3000...

1. The document discusses key events in the early history of life on Earth based on an events diagram. 2. It shows that the Earth formed 4600 million years ago, the first living organisms appeared 4000 million years ago, and organisms capable of photosynthesis first evolved 3000 million years ago. 3. The rise of oxygen in the atmosphere around 3000 million years ago is attributed to the evolution of photosynthetic organisms, as oxygen is a byproduct of photosynthesis.