AP BIOLOGY

Detailed explanation-1: -Annual growth rings tell us not only how old the tree was when it died but also the story of the travails it endured during its lifetime. Tree rings form in the trunk of a tree from new cells generated in the cambium, the meristem (growing point) that lies just beneath the tree’s bark.

Detailed explanation-2: -The cambium cells on the inside become the xylem, a system of tiny tubelike cells that carry the tree’s water supply. These xylem layers give us the annual rings.

Detailed explanation-3: -Due to differential seasonal activity of cambium (during autumn and spring season) alternate light & dense wood is cut off leading to formation of annual rings.

Detailed explanation-4: -The annual rings are formed by secondary xylem because the growth in spring and autumn seasons forms spring and autumn wood.