1. These are formed by division of trachea.   9   6   7   15   Hint Half-n-half Clue   2. It is a muscular tube containing semicircular rings of cartilages.   16   3   5   6   Half-n-half Clue   3. Exchange of gases occurs here.   12   7   6   10   Half-n-half Clue   4. Bile is stored here.   11   16   5   10   Half-n-half Clue   5. Bile is secreted here.   14   6   9   11   Half-n-half Clue   6. It pumps blood to various parts of the body.   7   3   13   8   Half-n-half Clue   7. Food descends from mouth to stomach through this muscular tube.   12   16   3   9   Half-n-half Clue