This drawing shows the internal anatomy of a sponge. what does the arrow down the middle represent?

Hey, I took that quiz. The answer was, the flow of water through the body of a sponge. I got an A so its right

Hope it helps :)

Explanation:

1. a plasma membrane and Eukaryotic cells have organelles surrounded by membranes. This includes mitochondria and a nucleus, where DNA is stored.

2. nucleoid

3. membrane organelles