2644 - CSUN ScholarWorks - California State University, Northridge

50 · Journal of Student Research Abstracts
2748
THE EFFECT OF CAFFEINE ON THE REGENERATION RATE OF PLANARIA
Dana Pong and Stephen DeGusta (teacher). John F. Kennedy High School, 6715 Gloria Dr., Sacramento,
CA 95831.
Caffeine is a stimulant that when taken in large doses leads to health complications. Doses over a certain
amount lose stimulant effects and take on depressant effects. Because it affects primarily the brain, the control
of all bodily functions, caffeine has a potential influence on growth. In this study I investigated the question,
"Does caffeine slow the regeneration rate of planaria?" My hypothesis was that if caffeine slows the regeneration
rate of planaria, then the experimental group will regenerate at a rate significantly slower than that of the
control group. Planaria were chosen as the subjects for study because of their notable ability to regenerate lost
parts. For my experiment twenty planaria were used-10 control and 10 experimental. Each planarian was
measured using a half millimeter ruler before its head was dissevered. The control was exposed to dechlorinated
tap water, and the experimental to Water Joe caffeinated water (3mg/25ml). The growth was observed by
daily measurement over a period of ten days. Along with the measurement, the day, date, and time of the measurement
were recorded. After the regeneration rates were calculated [(total amount of growth)/(number of
days)], it was determined that the control group regenerated faster than the experimental group. Results of the
t-Test yielded a p value less than 0.1, indicating that the results were significant in proving that caffeine does
slow the regeneration rate of planaria.
2749
EFFECTS OF COMMERCIAL SOLUTIONS ON BACTERIAL GROWTH.
L.R. Pool, A.P. Varela, L.M. O'Neill, DX Santoso and B. VanDuzee (teacher). Saugus High School, 21900
W. Centurion Way, Saugus, CA 91350.
This experiment examined the effectiveness of household antibacterial products in inhibiting the growth of
bacteria. In the experiment, performed three times, petri dishes were prepared with agar solution. After the agar
congealed, it was scraped with a copper wire so bacterial could permeate the agar. Then seven indicator disks
were each soaked in one of the following solutions: hand soap, kitchen cleaner, all purpose cleaner, shampoo,
anti-bacterial hand gel, dish washing soap, and medical disinfectant (Neosporin). The disks were placed in different
petri dishes, along with one disk left clean for control factor purposes. After spending one week in at
room temperature, 70 degrees, bacteria had developed on the agar. The control sample clearly had developed
the most bacteria, and had no visible ring of inhibition. The ring of inhibition is the area around the disks where
the bacteria didn't grow because of the antibacterial product. Therefore, the larger the ring of inhibition, the
more antibacterial potency the products contains. The shampoo, hand soap, kitchen cleaner, dish washing soap,
and all purpose cleaner all had small rings of inhibition with significant amounts of bacteria not far from the
disk. The average diameter of the rings from the three trials, including the diameter of the disk which was 0.4
centimeters (em), were as follows: 1 em for the hand soap, 1.2 em for the kitchen cleaner, 1.25 em for the all
purpose cleaner, 0.8 em for the shampoo, and for dish washing soap 1.15 em. The anti-bacterial hand gel and
the medicinal disinfectant had relatively large rings of inhibition in relation to the other disinfectants. The average
rings of inhibition were as follows: 2.4 em for the anti-bacterial hand gel and 2.9 em for the Neosporin.
These results show that using commercial solutions does inhibit the growth of bacteria, and anti-bacterial hand
gel and medicinal disinfectant are the most effective in blocking this growth.