Which organelle would you expect to see lots of in a cell with a high energy requirement (e. g., muscle cells, sperm cells)?

The organelle you would expect to see in abundance in a cell with high energy requirements is MITOCHONDRION.

The mitochondrion, which is known as the powerhouse of the cell is so named because it is the sight of cellular respiration, the main process providing energy.  As such, cells which are in need of a vast amount of energy would have a large supply being produced by having a plethora of mitochondrial organelles present in cells.

Active site is where they touch.