1. Exchange of gases occurs here.   14   2   7   5   Hint Half-n-half Clue   2. It is a muscular tube containing semicircular rings of cartilages.   7   3   2   5   Half-n-half Clue   3. It secretes saliva.   1   3   9   10   Half-n-half Clue   4. Absorption of food occurs here.   10   15   1   9   Half-n-half Clue   5. Bile is secreted here.   7   9   11   14   Half-n-half Clue   6. Undigested food is excreted out of the body through this opening.   16   7   1   15   Half-n-half Clue   7. Food is mixed with saliva here.   14   3   15   2   Half-n-half Clue