Umich Biology 173 Quiz 2 Practice
Exam All Solved Correct 2025.
Ecology - Answer The interactions of an organism with other organisms and with its
environment
Mutualism - Answer An interaction between two species in which both species benefit
Commensalism - Answer An interaction between two species in which one species benefit and
the other is unaffected
Predation/parasitism - Answer An interaction between species in which one species benefit
and the other is harmed
Neutralism - Answer An interaction between two species which interact without affecting each
other
Amensalism - Answer An interaction between species in which one species is harmed while
the other species is not affected
Competition - Answer An interaction between species in which both species are harmed
What is competition over? - Answer Limiting resource (food, water, light, nesting space,
pollinators, etc)
Who is competition between? - Answer Competition can be between two different species
(interspecific) or within a species (intraspecific)
If interspecific competition is less than intraspecifc competition it ..... - Answer allows for more
species to coexist
What does competition do - Answer Reduces growth, survival and/or reproduction of both
species
, theory of limiting similarity - Answer Species that are too similar cannot coexist
How do so many different species survive in nature? - Answer 1. Resource partitioning -
inferior competitors for one resource may switch to another (less ideal) resource, lessening
competition
2. Temporal and spatial patchiness - the best competitor may not always find the resources or
the inferior competitor may be able to use them for a time before found
3. Other factors (predators, disease, weather) may keep populations small; therefore, the
limiting resource might not be limiting at all
4. The outcome of competition depends on environmental conditions which vary
Mean - Answer the arithmetic average of a distribution, obtained by adding all the values and
then dividing by the number of individuals
Variance - Answer The difference between the value and the mean squared (distribution
about the mean); the standard deviation squared; tell how different one group is to the other
Divide the "sum of the squares" by sample size minus 1
standard deviation - Answer The square root of the variance
Sampling from a population - Answer The mean may not match the "true" mean of the
population
The smaller the sample size, the greater the chance of a bad mean
The larger the variance, the greater the chance of a bad mean
T-score - Answer A value that reflects how different two means are based on the difference
between them and the standard deviations and sample sizes of the populations they are based
on
P-value - Answer The probability that two means could drawn from the same population,
given a T-score and sample size; or, the probability that the difference seen is due to random
variation in sampling; or, the probability that two means are not significantly different
How do we decide whether observed differences represent true differences or random sample
variation? - Answer We do a T-test using means, degrees of freedom, and significance levels to
Exam All Solved Correct 2025.
Ecology - Answer The interactions of an organism with other organisms and with its
environment
Mutualism - Answer An interaction between two species in which both species benefit
Commensalism - Answer An interaction between two species in which one species benefit and
the other is unaffected
Predation/parasitism - Answer An interaction between species in which one species benefit
and the other is harmed
Neutralism - Answer An interaction between two species which interact without affecting each
other
Amensalism - Answer An interaction between species in which one species is harmed while
the other species is not affected
Competition - Answer An interaction between species in which both species are harmed
What is competition over? - Answer Limiting resource (food, water, light, nesting space,
pollinators, etc)
Who is competition between? - Answer Competition can be between two different species
(interspecific) or within a species (intraspecific)
If interspecific competition is less than intraspecifc competition it ..... - Answer allows for more
species to coexist
What does competition do - Answer Reduces growth, survival and/or reproduction of both
species
, theory of limiting similarity - Answer Species that are too similar cannot coexist
How do so many different species survive in nature? - Answer 1. Resource partitioning -
inferior competitors for one resource may switch to another (less ideal) resource, lessening
competition
2. Temporal and spatial patchiness - the best competitor may not always find the resources or
the inferior competitor may be able to use them for a time before found
3. Other factors (predators, disease, weather) may keep populations small; therefore, the
limiting resource might not be limiting at all
4. The outcome of competition depends on environmental conditions which vary
Mean - Answer the arithmetic average of a distribution, obtained by adding all the values and
then dividing by the number of individuals
Variance - Answer The difference between the value and the mean squared (distribution
about the mean); the standard deviation squared; tell how different one group is to the other
Divide the "sum of the squares" by sample size minus 1
standard deviation - Answer The square root of the variance
Sampling from a population - Answer The mean may not match the "true" mean of the
population
The smaller the sample size, the greater the chance of a bad mean
The larger the variance, the greater the chance of a bad mean
T-score - Answer A value that reflects how different two means are based on the difference
between them and the standard deviations and sample sizes of the populations they are based
on
P-value - Answer The probability that two means could drawn from the same population,
given a T-score and sample size; or, the probability that the difference seen is due to random
variation in sampling; or, the probability that two means are not significantly different
How do we decide whether observed differences represent true differences or random sample
variation? - Answer We do a T-test using means, degrees of freedom, and significance levels to
