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