Where are the Rocky Mountains?
Rocky Mountains The Rocky Mountains stretch all the way from the southern United States north into Canada. They through Utah, Colorado, Wyoming, Montana, and up into Alberta. What we call [...]
Rocky Mountains The Rocky Mountains stretch all the way from the southern United States north into Canada. They through Utah, Colorado, Wyoming, Montana, and up into Alberta. What we call [...]
Two and a half billion years ago, the Archaean Eon ended and the Proterozoic Eon began. Trillions of prokaryote cells lived in Earth's oceans. Some of these cells could photosynthesize their energy [...]
Ice chemistry: Perito Moreno glacier, Argentina (thanks to Argentina's Travel Guide) How water freezes into ice When water gets colder than 32 degrees Fahrenheit or zero degrees Celsius, it freezes [...]
Mushrooms growing in a field About 600 million years ago, a few eukaryote cells developed into multi-celled creatures. Some of them became animals, and some became plants, and others became [...]
Fish eggs: Egg evolution starts with soft eggs like these When did the first eggs evolve? The earliest living creatures made babies by dividing themselves in half, so that one [...]
RNA molecule: A single strand of RNA, seen under an electron microscope The RNA molecule was probably one of the earliest steps towards life on Earth. RNA is short for [...]
A cell dividing into two cells The first reproduction One of the main ways we define whether something is alive is whether it can reproduce - if it can make a new [...]
Chloroplasts (seen through a microscope) Photosynthesis is the way some cells on Earth pull in light from the sun and use it to make energy to repair and reproduce themselves. [...]
An onion skin cell (seen through a microscope) You can see the nucleus inside each cell The earliest cells, and all prokaryote cells, don't have a nucleus. Inside these simple [...]
A mitochondrion (seen through a microscope) When did mitochondria evolve? About two billion years ago, in the Proterozoic, there were only prokaryotic cells on Earth. Mitochondria probably started out as [...]