Apple Human Interface Guidelines: The Keyboard: 

Moving the insertion point with the arrow keys
<http://tinyurl.com/apple-hig-the-keyboard-mov>

> Option–Up Arrow
> To the beginning of the current paragraph, then to the beginning
> of the previous paragraph
> 
> Option–Down Arrow
> To the end of the current paragraph, then to the end of the next
> paragraph (not to the blank line after the paragraph, if there is
> one)

OOo misapplication of these key combination shortcuts — AFAICT affecting the height of cells (in Calc) 
and the height of rows (in tables in Writer) is a block to at least two bugs:

Issue 98954 (Calc, spreadsheet)

> modifier keys (shift, alt, command) with arrow keys (right, down, left, up) 
> fail to move insertion point, extend selection

Issue 98955 (Writer, word processor)

> alt-up and alt-down fail to move insertion point within table

— 

Need to:

a) first: cease to use alt-up and alt-down for manipulation of cells/rows/tables

b) then: maybe, carefully, find alternative key combinations shortcuts.