Saddleback Journal of Biology - Saddleback College

Spring 2010 Biology 3A Abstracts
4. THE EFFECT OF STEVIA ON MOUSE WEIGHT (Mus musculus). Seyed Soroush Pairawan and
Yumika Shimoda. Department of Biological Sciences, Saddleback College, Mission Viejo, CA, 92656,
USA
It has been supported by other studies that Stevia, a sweetener derived from the plant Stevia
rebaudiana, significantly decreases blood glucose levels by increasing insulin levels. As the blood
glucose level decreases, craving for food increases along with food consumption, which potentially leads
to weight gain. The investigators hypothesized that the Stevia fed mice would show a significant
increased weight gain compared with the control group. In this experiment, 15 adult mice (Mus musculus)
were used to determine the effects of Stevia on mouse weight gain. The mice were divided into two
groups, one group supplied with a Stevia water supplement and a control group with tap water. The
weight measurements of each mouse were taken every day at 1600 over a period of seven days. The
average experimental weight gain was 3.62 ± 0.86 g (± se, N=7), while the average control weight gain
was 2.25 ± 0.70 g (± se, N=8). Comparing the means of the average weight gain by an unpaired t-test (p =
0.12) revealed that there was no significant difference between the experimental and control group.
However, judging by the data collected, it is possible to suppose that Stevia could have a long-term effect
on the weight gain.
5. EFFECT OF LIGHT WAVELENGTH ON METABOLIC RATES IN Gromphadorhina portentosa
(Madagascan Hissing Cockroaches). Richard Triggs and Adam Gordon. Department of Biological
Sciences, Saddleback College, Mission Viejo, CA, 92692, USA
Insects have compound eyes, each made up of thousands of tiny eyes. These tiny eyes contain
photoreceptors in small eyelets called ommatidia. The light-sensitive part of an ommatidium is called the
rhabdom which contains an array of closely packed microtubules where light-sensitive pigments are
stored. These pigments absorb certain wavelengths of light and transmit nerve impulses through a
photochemical process similar to that of vertebrates. Considering the structure and function of the
compound eye, it was predicted that there would be a significant difference in the metabolic rates in
Gromphadorhina portentosa (Madagascan Hissing Cockroaches) when exposed to a constant intensity of
red and blue light . The average metabolic rate for the cockroaches in blue light was 3.06 ± 0.48 ml
CO 2 /g/day (± se). The average metabolic rate for cockroaches in red light was 3.55 ml ± 0.70 ml
CO 2 /g/day (± se). No significant difference in metabolic rates between the different light wavelengths was
obtained (p= 0.46, two-tailed, paired t-test).
6. A COMPARISON OF THE METABOLIC RATES IN MALE AND FEMALE MADAGASCAR
HISSING COCKROACHES (Gromphadorhina portentosa). Eden Perez and Sasha Jamshidi. Department
of Biological Sciences, Saddleback College, Mission Viejo, CA, 92692, USA
Metabolism is a chemical process that helps organisms maintain their physiological functions. Since
the metabolic rate of Madagascar Hissing Cockroaches (Gromphadorhina portentosa) is dependent on
size and gender, varying weights of male and female cockroaches were used to compare their metabolic
rates at rest. The objective of this experiment was to determine whether male cockroaches have a
significantly higher or lower metabolic rate than female cockroaches. It was predicted that male
cockroaches would have a significantly higher metabolic rate than female cockroaches. Five male and
female cockroaches were weighed and placed into separate containers. The CO 2 production for each
cockroach was measured for a span of ten minutes. The average weight specific metabolic rate for males
was 0.09 ± 0.019 mL CO 2 /hr/g (±se, N=5), while the average weight specific metabolic rate for females
was 0.17 ± 0.013 mL CO 2 /hr/g (±se, N=5). An unpaired, one tailed t-test (p=0.0061) revealed that there
was a significant difference in the mean metabolic rate between genders. The results rejected the
hypothesis since the female cockroaches had a significantly higher metabolic rate than the male
cockroaches. It is possible that sexual maturity in female cockroaches contributed to their high metabolic
rate.
152
Saddleback Journal of Biology
Spring 2010