Activity 2. Crossword Puzzle Read the clues below. Copy the boxes and write the letter of your answer inside the box. 2 Also called as the air sacs 1. It is also called as the windpipe 3. Analogous to the small stems of grapes 6. It corresponds to the two major branches of the grapes Down 5 2. Also called as the air sacs 4. Thin muscle that contract and relaxes to help the air go in and out of the lungs 5. The organ which air enters first (0000)B tems: working with other organ systems Workbook Science​