- Sample lab report -
Sean Hammer
Denise Clark
20 September 2010
Biology – Block 1
Is there a single environmental factor that affects the chirping rate in crickets?
Purpose: To determine the environmental cause of changes in the chirping rate of crickets.
Hypothesis: The chirping rate of crickets varies directly with air temperature. In other words, when air temperature increases, so does the chirping rate and vice versa.
Materials: Cricket, counter, timer, meter stick, thermometer, barometer (to measure atmospheric pressure), hygrometer (to measure humidity), anemometer (to measure wind speed).
Procedure:
1. Locate cricket for study.
2. Count total number of chirps for duration of one minute. Repeat ten times and calculate/record the average number of chirps per minute.
3. Record atmospheric conditions including temperature, atmospheric pressure, humidity, number of crickets nearby, and wind speed.
4. Repeat on at least three additional days using same cricket each time.
Data/Observations:
Table 1. Periodic observation of chirping rate in a single cricket
Date / Time / Chirping Rate3/21 / 6 am / slow
6/21 / 2 pm / fast
9/21 / 8 pm / Medium
Table 2. Environmental conditions (constants) during experiment
Controlled Variable / Established LevelAtmospheric pressure / 760 mm Hg
Humidity / 15%
Number of crickets nearby / 5
Wind speed / 2 m/sec
Table 3. Effect of Air Temperature on Chirping Rate of Crickets
Air Temperature (°C) / Average # of chirps per minute5 / 4
10 / 40
15 / 76
20 / 112
25 / 148
30 / 184
35 / 220
40 / 256
45 / 292
Analysis:
Analysis (continued):
1. Which of the following factors determines the chirping rate in crickets?
A) Air temperature
B) Atmospheric pressure
C) Humidity
D) Number of crickets nearby
E) Wind speed
F) None of the factors above
The chirping rate in crickets is determined by A) air temperature.
2. If you increase the air temperature, the chirp rate will:
A) Decrease
B) Increase
C) Stay the same
If you increase the air temperature, the chirp rate will increase.
3. If you double the air temperature, the chirp rate will:
A) Double
B) Be halved
C) Remain the same
D) None of the above
If you double the air temperature, the chirp rate will increase but not double.
Conclusion:
My hypothesis was that the chirping rate of crickets varies directly with air temperature. Our experimental results support this hypothesis. As temperature increases from 5°C to 45°C, the chirping rate increases linearly from 4 chirps per minute to 292 chirps per minute. The data clearly demonstrates that a 5°C increase in temperature corresponds to a 36 chirp per minute increase in the chirping rate of crickets. This result suggests that one could use the number of chirps per minute as a means of calculating the air temperature and thereby use the cricket as a natural thermometer.
It is important to note that we used the same cricket as the object of study throughout this investigation. We cannot rule out the possibility that our chosen cricket had an abnormally high or low chirping rate. Similarly, it is possible that our observed cricket’s chirping rate displayed unusual temperature dependence that belies the true relationship between the variables in the larger population. Also, we neglected to take into consideration time of day when conducting our measurements. Since air temperature fluctuates throughout the day with changes in sunlight, we have not yet demonstrated that the observed relationship between temperature and chirping rate is not due to some other confounding variable such as light intensity.
Additional research is needed to verify our present findings. Such studies should repeat the above procedures using a larger sample size of crickets. Measurements should be taken at the same time of day and throughout the year during different seasons in an attempt to control for the effects of changing light intensity. While our results need further validation, the results of our experiment clearly suggest a very strong link between air temperature and chirping rate in crickets.
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