ANSWERS

QUESTIONS

1. Why did this activity require two test tubes, if only one was needed for the Elodea sprig?
   (Test tube "B" served as the control, while "A" was the experimental setup.)
2. What happened to tube "A", into which the Elodea sprig was introduced?
   (Other organisms began growing in and on the inner surface of the tube.)
3. What happened to tube "B"?
   (Most likely, this tube retained the same sterile appearance - unless it was accidentally infected with organisms.)
4. What types of organisms were transferred along with the Elodea sprig?
   (Answers will vary but may include snails, other types of algae, rotifers, copepods, and various protozoa species.)

EXTENSIONS

Sterile Transfer
Suppose you wanted to introduce Elodea, and only Elodea, into a new environment. How could you improve the transfer technique so that few if any unwanted organisms were imported into the new environment?
(Accept all reasonable answers such as swiping plant surface with alcohol, isolating sprigs before transferring them, etc.)