History of life

High school (ages 12+)
Animals & Nature

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/history-of-life

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the atmospheric transformation?The Great Oxygenation Event (~2.4 Ga) fundamentally changed Earth's atmosphere
2. What is the earliest evidence of life on Earth?Scientists found tiny life signs in rocks that are about 4.28 billion years old. Those early life forms were simple microbes that lived near hot vents deep in the ocean, far from the sun.
3. How did oxygen first appear in the atmosphere?Around 3.5 billion years ago, tiny plant‑like bacteria called cyanobacteria started making oxygen when they used sunlight. At first the oxygen was used up by iron, but after about 2.4 billion years the planet’s surface filled with oxygen in a big change called the Great Oxygenation Event.

Abiogenesis: The natural process by which life arises from non-living matter.
Endosymbiosis: A symbiotic relationship where one organism lives inside another, leading to complex cell structures.
Phanerozoic Eon: The current geologic eon, spanning from about 541 million years ago to the present, characterized by abundant animal life.
Bilateria: Animals possessing a distinct left and right side, forming a mirror image.