Topic
Pigments
2 articles
Biology
Why does a cut apple turn brown?
A whole apple sits in the fruit bowl all week and looks the same on Sunday as it did on Monday. Cut one at breakfast and it is the color of weak tea by lunchtime. Nothing was added to it.
Biology
Why do some leaves turn red before they fall?
The yellow in an autumn leaf was hiding under the green all summer long. The red was never there at all. A tree builds that color from scratch, in the last two weeks of a leaf it has already decided to drop.