Although I usually use the Split Cells command, as Máté Juhász suggests, another way to do this is to use Word's Draw Table tool.
Select the table, or make sure that the cursor is somewhere inside it, and then, on the Table Tools > Layout tab, in the Draw group, click Draw Table.
Then just draw in horizontal lines between the paragraphs that you want to split into rows. Word will break the single cell into multiple rows.
Note, however, that the Draw Table tool is a bit fussy. If you don't draw the line in just the right place between paragraphs, you end up with extra rows or rows inserted between paragraphs other than the ones that you intended.
Tip: I always find that I need to basically draw right through the middle of the text in each paragraph to get the tool to work the way I want. So, to get the table to divide between paragraphs 1 and 2, draw through the middle of the line of text in paragraph 1. Then draw through the middle of the text in paragraph 2 to divide the table between paragraphs 2 and 3, and so on.
You'll probably also end up with extra space at the bottom of the last row, as shown below. In this case, just drag the bottom border upward until the extra space disappears. (Be sure to turn off the Draw Table tool first, either by clicking the button again or by pressing Esc.)
Update: I was assuming that your screenshot reflected the actual size of your tables. If, as you say, you're dealing with tables that have 150 paragraphs, this solution, which would otherwise be very quick (once you become accustomed to the tool), will obviously be too much work.