Study the timeline. A timeline. 4.5 billion years ago, Earth is formed. 4.3 billion years ago, Earliest water. 4.1 billion years ago, Single celled life. 3.5 billion years ago, Earliest oxygen and photosynthesis. 2.5 billion years ago, Complex single celled life. 1.5 billion years ago, Multi cellular life. 500 million years ago, Land life. 300 million years ago, Dinosaurs. 200 million years ago, Mammals. 130 million years ago, Flowers. 5 million years ago, Humans. Based on fossil evidence, about how long ago did the first single-celled life form appear on Earth? 130 million years ago 1.5 billion years ago 2.5 billion years ago 4.1 billion years ago

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.

Which diagram best represents the chromosomes that would be found in a two new skin cells produced as a result of this process?

Which describes the changes in the earths motion?