2644 - CSUN ScholarWorks - California State University, Northridge

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58 · journal of Student Research Abstracts
leaves, number of bunches, discolored leaves, and physical observations were taken. Results such as length of
leaves were not taken. This is mainly because there would be no significant growth since the duckweed were
already full-grown when obtained. Following approximately two weeks of observations and measurements, I
found that the potassium did not increase the multiplication or growth. It actually killed a large population of
duckweed in each experimental tray. After a statistical analysis of the data, I concluded that the 1% solution
of potassium nitrate, KN0 3 , decreased the rate at which duckweed multiplied. (P < 0.01)
2768
THE EFFECTS OF liGHT INTENSITY ON THE EATING HABITS OF BROWN
GARDEN SNAilS.
Jackson Thach and Steve DeGusta (teacher). John F. Kennedy High School, 6715 Gloria Dr., Sacramento,
CA 95831.
In this experiment, I wanted to find out if light intensity affected the amount of food eaten by Helix aspera,
or the brown garden snail. To do this, I took twenty snails and separated half of them into two different categories:
light and dark. Each category was named for the light intensity chosen. The snails were placed into two
containers, with ten snails in each. In the dark category, the container was placed in a paper bag to encourage
low light intensity. In the light category, no bag was placed over the container so that all the light would be
able to pass through. I fed the snails in each category lettuce. I weighed the lettuce before and after I fed the
snails to see how much they ate. My results suggested that the snails in light ate more than the snails in the
dark. On average, the amount of lettuce ate by the snails in light was 7.47 grams per day. For the ones in the
dark, it was 5.89 grams per day. But after using the t-test, I resolved that my data collected was due to chance
(p>O.l). Therfore, I conclude that light intensity does not affect the amount of food eaten by Helix aspera.
2769
THE EFFECTS OF EGG YOlK AND CITRIC ACID ON THE BEHAVIOR OF
DUCES/A TIGRINA
Ryan D. Fong, Stephen DeGusta (teacher). John F. Kennedy High School, 6715 Gloria Drive, Sacramento,
CA 95831.
In this investigation, I completed a series of labs to test the effects of egg yolk and citric acid on the
approach and avoidance patterns of the planarian, Dugesia tigrina. I hypothesized that the planaria would
respond to egg yolk, a food source, with an approach behavior, and respond to the citric acid, a toxic substance,
with an avoidance behavior. Placing planarians in a y-maze with egg yolk and citric acid in left branch in two
separate tests measured this. The left and right decisions made by the planarians were recorded. A left decision
would indicate approach behavior, whereas a right decision would indicate avoidance behavior. The data
showed that there was no significant difference between the number of left and right decisions when egg yolk
was present, but it also showed that there were significantly more right decisions compared to left when citric
acid was present (X 2 =9.8, p=.01). This suggested avoidance behavior. The second experiment was to test the
effects of citric acid on planarians conditioned with electric shock. They were conditioned to go left in a ymaze,
by shocking them every time they chose right. Citric acid was then placed on the left. The number of
left and right decisions were recorded and statistically analyzed. The data showed that there were significantly
more right decisions (X 2 =5.0, p=.05). This showed that the avoidance behavior to citric acid was stronger
than to electric shock.