AP BIOLOGY

Detailed explanation-1: -Start in the middle of the stump or cross-section of wood and count the first dark ring you see. Continue counting outwards from the middle ring until you reach the last dark ring. The total number of dark rings represents the age of the tree in years. (Don’t count the bark of the tree as a dark ring.

Detailed explanation-2: -Every year, trees form new cells arranged in concentric circles. These concentric circles are called annular rings. By counting these rings, the age of a tree can be estimated.

Detailed explanation-3: -Krishna determined the age of a tree by counting its annual rings which actually are the xylem rings. Tree trunk growth results primarily from the xylem layers and is counted to determine the age.

Detailed explanation-4: -Thus, two zones of secondary xylem are formed each year and both can be easily demarcated. These two zones constitute an annual or growing ring. By counting the number of rings, it is possible to know the age of the plant. The research is known as dendrochronology.