If a tree has 10 dark rings and 10 light rings, how old is the tree?

Wouldn't the tree be twenty years old. Since each ring is 1 year.

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.

What have scientists learned about plant behavior by studying the dodder plant