BIS 2B PRACTICAL EXAM 2025
QUESTIONS AND ANSWERS
Shannon-Weiner Index - ANS how many species occur and their relative abundance
How H' is calculated - ANS -find the p1 by # of organism / # of individuals of all species
- log(10)(p1)
- convert this to log(2)(p1) by multiplying by 3.322
- add all of the log(2)(p1) for each species together
- multiply the final value by -1 to get a positive value
Operational Taxonomic Unit (OTU) - ANS distinct groups of organisms based on their
appearance alone
Transect Sampling - ANS A line is run through a habitat and every organism within a fixed
distance of that line is recorded
Quadrant Sampling - ANS habitat is divided into rectangles and random ones are chosen for
sampling
What does a species vs. individuals (rarefaction) graph tell you that a population (N) vs. time
graph does not? - ANS rarefaction graph tells us if we have sampled most, if not all, species
in a habitat by its leveling off. N vs. t tells us how a particular species population is growing over
time.
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, Randomizing in subsampling is important because: - ANS it removes bias which may lead to a
sample not representative of the population as a whole. The goal in surveying is to get a
representative sample without literally surveying the entire habitat.
Can rarefaction plots can tell us how many individuals of each species are present in a
community? - ANS No,they cannot because they are a combination of all our data and thus
do not distinguish how many individuals of particular species are present.
Diversity is a measure of... - ANS Species richness and species evenness
Rarefaction curve - ANS -finding good estimate of true diversity of habitat
-curve levels off to a horizontal line meaning you have a good estimate when no matter how
many more indiv. you collect, you aren't finding anymore preciously uncollected species
-plot # combined indiv. (x) vs. # combined species found (y)
Lab 1: - ANS Diversity: Sampling
Limitations of OTUs - ANS When using OTUs, there is acknowledgement that we cannot say
with certainty that they are different species. We acknowledge that these judgments are based
purely on appearance and are subject to related limitations.
Among the two flower morphs what evidence is there, from what you learned in that lab, that
phenotypic variation has a genetic basis? - ANS the presence of a "Y" allele gives a green
plant anbd the genotype "yy" produces a yellow one
Why do we take many samples and average the results? Why did we not just take one sample
for each? - ANS It is unlikely that a single sample would be a good representative sample.
Getting many samples and averaging the results is more likely to yield a good representative
sample.
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED 2
QUESTIONS AND ANSWERS
Shannon-Weiner Index - ANS how many species occur and their relative abundance
How H' is calculated - ANS -find the p1 by # of organism / # of individuals of all species
- log(10)(p1)
- convert this to log(2)(p1) by multiplying by 3.322
- add all of the log(2)(p1) for each species together
- multiply the final value by -1 to get a positive value
Operational Taxonomic Unit (OTU) - ANS distinct groups of organisms based on their
appearance alone
Transect Sampling - ANS A line is run through a habitat and every organism within a fixed
distance of that line is recorded
Quadrant Sampling - ANS habitat is divided into rectangles and random ones are chosen for
sampling
What does a species vs. individuals (rarefaction) graph tell you that a population (N) vs. time
graph does not? - ANS rarefaction graph tells us if we have sampled most, if not all, species
in a habitat by its leveling off. N vs. t tells us how a particular species population is growing over
time.
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED 1
, Randomizing in subsampling is important because: - ANS it removes bias which may lead to a
sample not representative of the population as a whole. The goal in surveying is to get a
representative sample without literally surveying the entire habitat.
Can rarefaction plots can tell us how many individuals of each species are present in a
community? - ANS No,they cannot because they are a combination of all our data and thus
do not distinguish how many individuals of particular species are present.
Diversity is a measure of... - ANS Species richness and species evenness
Rarefaction curve - ANS -finding good estimate of true diversity of habitat
-curve levels off to a horizontal line meaning you have a good estimate when no matter how
many more indiv. you collect, you aren't finding anymore preciously uncollected species
-plot # combined indiv. (x) vs. # combined species found (y)
Lab 1: - ANS Diversity: Sampling
Limitations of OTUs - ANS When using OTUs, there is acknowledgement that we cannot say
with certainty that they are different species. We acknowledge that these judgments are based
purely on appearance and are subject to related limitations.
Among the two flower morphs what evidence is there, from what you learned in that lab, that
phenotypic variation has a genetic basis? - ANS the presence of a "Y" allele gives a green
plant anbd the genotype "yy" produces a yellow one
Why do we take many samples and average the results? Why did we not just take one sample
for each? - ANS It is unlikely that a single sample would be a good representative sample.
Getting many samples and averaging the results is more likely to yield a good representative
sample.
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED 2
