Bio lab 2 notes Oct 20 2009
Bio lab 2 t orientation of isopods
Scientific method are: preliminary pbservation, problem, hypothesis, experiment ot controlled
observation and theory
Cyclical t the experiment provides more accurate pbservation permitting a refinement pf the problem,
starting the process again.
The quality of the scientific work depends on the correctness of the observation
Before approaching a problem, the observation should determine what scientifix problem to
address in the experiment.
After observation t need to define a problem
Fundamental part of the scientific method is the recognition of good problems!
Bes problems should be relevance and the capacity to be tested
Guess a answer to the problem t hypothese
Hypothesis are not random guesses but are statements based on all of the relevant observations
A fundamental feature of the scientific method is that hypotheses are never be proven, they can
only be disproved t null hypothese
Null hypothese (H0) t assume the experimental treatments will have no effect. t the observed
difference between the treated and nutreated groups will not be statistically significant.
Experiment or controlled observation:
Ideal biobogical experiment is one in which the effects of 2 or more treatments are compared, and
untreated (control) organisms are used as a reference.
Interaction between various factors are involved in the experiment, factorial experiment t effects of
2 or more factors are determined simultaneously each at 2 or more levels in all possible
Replicates t as least 2 per treatment. Avoid confounded effects
Need a control group
Theory t when a hupothesis has been supported by a great mass of evidence and has been shown to be
extremely reliable in certain limit t accepted as a theory
Natural laws: theories that have been tested and shown to be universally valid are sometimes described
as a natural law
Orentiation in isopods: an application of scientific method
Orientiation behaviours t behaviour refers to actions in response to stimuli
Behaviour pattern t a sequence of movements in space and time
Orientation t the process that animals use to organize theis behaviour with respect to spatial features
Orienting responses t kinesis and taxis
Taxis t Zv]uo[}Ç]}]v]v}u]ouvv]v}v}Z]uµo]
Kinesis t movement }(Zv]uo[}Ç]v}v}]uµoµ]]vv}u]]}v
Stimuli types: gravity (geo-), chemical (chemo-) light (photo-) temperature (thermo-) and humidity
Towards stimuli t positive, away from stimuli t negative