Which cells in a tree experience greater deformation under bending loads?

The correct choice highlights that outer cells in a tree experience greater deformation under bending loads. This is primarily due to their location and the function they serve within the tree structure.

As a tree bends, the outer cells are subjected to tensile and compressive forces. The outer layer of wood, or sapwood, contains living cells that carry water and nutrients and are typically where the greatest stress and deformation occur during bending. These cells expand and contract based on these forces, leading to visible changes in the wood’s structure.

In contrast, the inner wood cells, which are primarily composed of older, inactive xylem, are less involved in these dynamic processes. They provide support but do not experience the same degree of deformation as the outer cells due to their closer proximity to the center of the tree, where bending stresses are less intense.

In essence, the outer wood cells react more significantly to bending forces because they are directly exposed to the external loads and their position allows them to deform in response to these forces more readily than the inner cells or cambium layers. The cambium cells are primarily responsible for the growth of new wood and secondary phloem, and do not experience bending stress in the same way as the established outer wood cells.