The answers to the first nine questions are two-word phrases that differ by one letter. For example- "Crimson water plant"= red reed. Keep track of the letter that's inserted in each question. Taken in order, they will be the answer to the tenth question.
-4.Stroke soil from a bog.
-8.Acquired a painful joint disorder caused by uric acid crystals.
10.Now take all of the added letters in order. What word do they spell?