Some plants increase in height due to changes in specialized regions of cells in the tips of their branches. the processes that result in these changes include

mitosis, cell growth, and differentiation

Explanation:

There are several ways through which plants grow which may include the process of mitosis mainly that involves cell division. The increase in height in plants is attributed to not only cell division but also growth of the newly formed cell.

Mitosis involved division of cell and in cell growth, cells increase their size that ultimately cause growth of plant height. The highly active growth cells are meristem cells that are found at tips of the plants. They are actively dividing zones of plants and with their division and growth plant increases their heights.

Another mechanism, responsible for increase in height is cell differentiation. Differentiation is the process during which cells are specialized to perform specialized function. For example: Xylem are specialized for transport of water. Phloem are specialized for the transport of food. Similarly, some cells are specialized for growth and they are aimed at increasing in size and division that ultimately increase the plant height.

So, mitosis, cell growth, and differentiation are the mechanisms, that increase plant height due to changes in specialized regions of cells in the tips of their branches.

Hope it helps!