What is the internal lining of many organs called?

Hemoglobin is the compound in red blood cells that carries oxygen to the body. the distribution of hemoglobin in women in g/dl of blood is approximately normally distributed with mean 14 and standard deviation 1. too little hemoglobin, and you're anemic. 2. too much, and (unless you live at high altitudes), you can have other problems.

What role do traits play in affecting an organisms ability to reproduce? finches

What was the land like over 500 million years ago? what was under the sea?