LAB EXAM Flashcards
what are the steps of the scientific method?
- observation leading to a question
- formulate a hypothesis (tentative explanation)
- design experiment to test hypothesis (control of experimental)
- collect and interpret results
- evidence fails to reject hypothesis or evidence rejects hypothesis
- of evidence fails to reject hypothesis you make a scientific theory which allows you to develop more questions
- if evidence rejects hypothesis device hypothesis
what is a hypothesis ?
a proposed explanation of a phenomenon, pattern, or set of observations that is both testable and falsifiable
what is a key feature of the scientific method?
hypotheses can never be proven- we can only reject them or fail to reject them
what is the null hypothesis (H0)
assumes that the experimental treatment will have no effect, or that there will be no significant difference between the control and experimental groups
what is a alternative hypothesis (HA)
when testing a hypothesis and the results of the experiment show that the null hypothesis is rejected you base the results on a alternative hypothesis
which states that is a significant difference between the control and experimental groups. The treatment did have an effect- but we cannot say we have proved this
how do you test a hypothesis?
by experimentation, a experiment is a test formulated with clear predictions of what will happen if the hypothesis is rejected vs the outcome if it is not.
what is the independent variable
variable that is not influenced by other materials in the lab. The variable in the lab that is manipulated in the experiment independently than the rest.
what is the dependent variable ?
the factor that responds to changes in the independent variable, or the measured outcome of the manipulation, is the dependent variable. ( it is the effect of the manipulations to the independent variable)
what is a control treatment
it is what is done when the assumption that dependent (responding) variables are only due to the independent (manipulated) variable
the control treatment confirms the experimental setup does not influence the dependent variable.
what Is the experimental treatment
will demonstrate where the independent variable has an effect
what are constants?
the factors in the experiment that are constant or stay the same except for the one variable that you are manipulating or is independent from the rest
what is replication?
to attain reliable results the experiment is repeated several times under the same conditions this is known as replication
- helps to make a accurate conclusion
what is a population mean
The population mean is an average of a group characteristic.
this is not accurate way because you would need to test every individual data to obtain a population mean
more accurate would be a sample mean
what is a sample mean
measuring a sample of the population to obtain a sample mean which is an estimate of the population mean
this is the formula for sample mean tell me what each variable represents
sample mean= the X with the bar on top
Xi= sum of all the data values
divided by n= number of individuals in the sample
how can there be variability in data?
- every time we measure something in our labs there will be variability because of the level of imprecision because we cannot be fully precise in our measurements
- individual organisms such as animals and plants even though are the same gender or from the same species will never be 100 % identical to one another
- your sample represents a small portion of the entire population of organisms, and. so only estimates how the population responds to your treatments
how can the variability of data be reduced?
by increasing sample sizes and carrying out multiple replicants of an experiment
Explain how to calculate SEM
If SEM values do overlap how would you word it?
Two means are likely similar
If SEM values are not overlapping, how should you word it?
Then we conclude that the means are likely different
What are the conversions when converting the calibration factor for the objective lens being used?
under the 10x objective, 1 ocular division= 10um
under the 40x objective, 1 ocular division= 2.5 um
under the 100x objective, 1 ocular division= 1um
You multiply this by the measurement (tick marks) under the ocular division.
What is a scientific theory
A broadly applicable idea or hypothesis that every conceivable test has confirmed
What is a spectrophotometer? and explain how it works
It is used to measure how much light a solution absorbs relative to how much light passes through the solution (transmittance).
- light is passed through the solution placed in the spectrophotometer; the solution will absorb some, and some will be transmitted. The higher the concentration of the coloured pigment ( the darker the solution), the more significant the absorbance.
- the transmitted light strikes a photocell, which converts the light energy into an electric current, which can be measured by a meter
SPECTROPHOTOMETERS MEASURE THE ABSORBANCE OF LIGHT BY A MOLECULE, NOT THE ABSORBENCY OF A MOLECULE
What is the standard curve?
displays the relationship between the absorbance and concentration for that pigment
What is the formula for dilution?
volume of original solution/(volume of original solution +volume of diluent)
What is the diluent?
is a solution that the volume of stock solution pipetted is put into
What is the formula to find concentration?
cd= Cu x D
cd= concentration of diluted sample
Cu= concentration of undiluted (original) sample
D= dilution
How do you prepare a fixed volume of specific concentration from the stock solution?
V1C1=V2C2
V1= volume of the original or stock solution
C1= concentration of stock solution
V2= volume of the new solution
C2= Concentration of new solution
What is a blank solution?
In simple terms, a blank solution in a lab experiment is like a control or a baseline. It’s a mixture that has everything in it except the thing you’re actually testing for. By using this blank solution, scientists can make sure that any measurements they take are only because of the thing they’re interested in, and not because of other stuff in the mixture or the equipment they’re using. It’s like setting a scale to zero before weighing something – you’re making sure you only measure what you want to measure.
What is the Vmax
is the maximum rate at which an enzyme can catalyze the reaction under the condition of the experiment.
At Vmax all enzyme molecules are complexed with substrate molecules and adding additional substrate will not speed up the rxn.
What Km
Is the substrate concentration at which the reaction proceeds at its maximum catalytic efficiency
It’s half of Vmax
What is a competitive inhibitor?
Are similar in shape to an enzyme substrate and compete with the substrate for binding to the active site
What is a non-competitive inhibitor?
do not compete with the substrate for the active site, but instead bind to other sites on the enzyme.
What is the meaning of oligotrophic?
Healthy aquatic ecosystems are relatively low in dissolved nutrients and are described as oligotrophic.
oligo= few
trophic= relating to nutrition
What is the meaning of eutrophic?
eu= good, true
aquatic ecosystems have high nutrient levels and tend to be dominated by algae and/or other aquatic surface plants, which is generally not a desirable state
What is eutrophication?
It is the process by which a body of water becomes enriched in nutrients from terrestrial ecosystems, and it can happen by natural methods. Still, human activities such as adding fertilizer to aquatic systems often cause or at least speed up the process.
What are the primary nutrients needed by plants and algae?
nitrogen, phosphorus, and potassium
Why is potassium essential for plants and algae
It is essential because of its important role in maintaining turgor pressure in plant cells and in the activation of many enzymes.
What is zooplankton
feeds of phytoplankton lower chamber
What is phytoplankton
Are the foundation for most aquatic food webs and tend to be quite short-lived, responding to increased nutrient availability with rapid increases in population growth
