PRACTICE QUESTIONS FOR EEB 483, EXAM #1
Please define the following terms and explain briefly why each term has significance in limnology
(3 POINTS EACH).
assimilation
photoinhibition
vertical migration
detritus
light-dark bottles
critical mixing depth
Leibig’s law
mixotrophy
Rayleigh scattering
cirque
Secchi disk
neuston
littoral
crenogenic meromixis
oligomictic
extinction coefficient
maar
caldera
seston
euphotic zone
Please fill in the blanks or circle the correct answer.
1. Lake types or basin shapes resulting from tectonic movements of the earth include
________________________ and ____________________________.
2. Geological activity during the earth's recent past (last 30,000 years) has tended to increase /
decrease / keep unchanged the number of lakes present in North America.
3. Endemic species are a characteristic of _______________________ lakes.
4. Light is attenuated in lake water by a combination of two physical phenomena:
_________________________ and _________________________.
5. Particulates in water absorb light mainly at high / low / all wavelengths.
6. A tropical lake has a surface temperature of 27 degC and a bottom temperature of 24 degC,
while a similar sized temperate lake has a surface temperature of 11 degC and a bottom
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temperature of 7 degC. Which lake has the greater density difference between surface and
bottom waters and why?
(a) The temperate lake, because there is a greater range of temperature from top to bottom.
(b) The tropical lake, because coriolis forces (earth's rotation) that would increase mixing
are small or absent.
(c) The tropical lake, because the rate of change of density with temperature increases with
increasing temperature.
(d) Both lakes have the same density difference.
7. What mechanisms do phytoplankton use to prevent sinking?
a. manipulation of Stoke's law through changing gene frequencies
b. making gas vacuoles
c. increasing their lipid content
d. attaching themselves to neutrally buoyant detritus
e. b and c
f. b, c, and d
8. Bluegreen algae may dominate during later summer in some lakes for the following 3 reasons:
(a) ___________________________________________________________________
(b) ___________________________________________________________________
(c) ___________________________________________________________________
9. List 2 ecological types (growth forms) of aquatic macrophytes and give one example (genus or
common name) for each:
a. ___________________________________________________________________
b. ___________________________________________________________________
10. Physical mechanisms or conditions that control the zonation of littoral biota include
__________________, _____________________, and _______________________.
11. Which of the following is NOT a reason why stream insects drift:
a. the critical density of organisms is too high
b. the risk of predation is reduced
c. the local food resources are too low
d. the organisms accidentally lose their hold on the substrate
12. Give two examples of factors that control the regional distribution of zooplankton.
a. ___________________________________________________________________
b. ___________________________________________________________________
13. The proximate / adaptive cause for cyclomorphosis / vertical migration is light /
predation.
14. According to the river continuum hypothesis, the production to biomass ratio (P/R) should be
<1 / >1 at low / middle / high stream orders.
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15. The “size-efficiency hypothesis” states that:
a. bacteria of any size are more efficient at nutrient uptake than algae
b. vertebrate predation is less efficient on zooplankton of smaller sizes
c. smaller zooplankton are less efficient at feeding and metabolism than larger
zooplankton
d. any organism of smaller size is more efficient at hiding from predators than larger
organisms
e. a and b
16. Please list two attrition (population reduction) controls of phytoplankton populations
a. ________________________________________
b. ________________________________________
17. Please list two growth controls of phytoplankton populations
a. ________________________________________
b. ________________________________________
18. The finite birth rate (B) is directly proportional to ___________________ and inversely
proportional to ________________________.
19. The resting eggs of Cladocera are haploid / diploid / triploid, and are capable of hatching into
females / males / males or females.
20. List 2 adaptations of aquatic macrophytes to their habitats
a. ___________________________________________________________________
b. ___________________________________________________________________
21. Based on analogy with Bosmina / Diaptomus, it seems likely that the horned form of
Ceriodaphnia found in Gatun Lake may have been more / less / just as susceptible to
successful attack by vertebrate / invertebrate predators than was the unhorned form.
22. Morphological adaptations of benthic invertebrates to life in running water include
_______________________________ and ________________________________.
23. Briefly describe the change in system "trophy" (production to biomass ratios) between typical
1st order, 5th order, and 10th order streams as would be predicted by the river continuum
concept.
24. The 14-C method of measuring primary productivity has more / less / the same sensitivity as
the oxygen change method.
25. Briefly describe one adaptation of littoral biota to each of the following conditions: (a) low
light, (b) CO2 availability
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Select taxa from the following list to answer questions on this page. There may be more
than one correct answer per question. 1 point for each correct answer; minus 1 point for
each wrong answer. Minimum score per question is 0.
Heterocystous Cyanophyta
Dinoflagellates
Centric Diatoms
Rotifers
Euglenophyta
Leptodora
Asplanchna
Asterionella
Brachionus
Chlorophyta
Plecoptera
Chaoborus
Cladocera
Pennate diatoms
Calanoid Copepods
Diptera
Daphnia
Cyclotella
Bosmina
Chlorella
Chrysophyta
Odonata
Chlamydomonas
Mollusca
Cyclopoid Copepods
Chlorophyta
Anabaena
Oligochaeta
Ceriodaphnia
Epischura
Diaptomus
Ephemeroptera
1. Chemical factors called morphogens have been found to induce developmental polymorphisms in
these animals.
2. These arthropods have obligate gametogenic reproduction (i.e., they are NOT parthenogenetic).
3. These algae have the ability to reduce N2 during nitrogen fixation.
4. These algal divisions or genera possess chlorophylls a and b just like higher plants.
5. Sex determination is based on ploidy level (i.e., haploid, diploid, etc.) in these animals:
6. These zooplankton taxa are often successful because of their small body sizes when planktivorous
fish are present.
7. These algae require the element Si for use in constructing cell walls, spines, or scales.
8. Motility in these algal groups is based on the use of flagellae.
9. These animals are important members of the animal benthos.
10. These animals can diapause in a post-embryonic instar:
11. These algal divisions or genera contain heterotrophic or mixotrophic species.
12. These taxa are important components of the lotic (stream) insect community:
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Please provide a short but complete answer for the following question:
1. What processes contribute to changes (either increases or decreases) in epilimnion thickness?
How could you determine which processes caused any given change (what measurements
would you make to find the cause)? (10 POINTS)
2. It has been said that the thickness of the epilimnion in lakes is a function of solar radiation,
transparency of the water, and wind conditions. Please explain (10 POINTS).
3. Describe the basic (~ 6) patterns of stratification in lakes?
4. How is the apparent color of blue produced in a lake?
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5. Two similar lakes affected by the same climatic and geologic conditions are quite different
limnologically. In one lake spring turnover lasts for a week, while in the other lake the turnover
lasts for six weeks.
(a) Why do the two lakes differ? (5 POINTS)
(b) What would happen if one of the lakes failed to mix in either the spring or the fall for
many years? (5 POINTS)
6. Describe the common methods used to measure aquatic primary productivity, and pick and
justify which method you would use to study (a) an oligotrophic lake in the Arctic, (b) an
eutrophic lake in Michigan, and (c) a slow-flowing river in the Amazon.
7. How does the finite birth rate (B) relate to or how is it used in models of zooplankton growth.
(5 POINTS)
8. List the 4 functional groups (guilds) of organisms (mostly they are insects) in streams and
briefly describe their ecological roles in the ecosystem. (8 POINTS).
9. Describe at least one possible adaptive cause of cyclomorphosis and give an example of the
effects. (4 POINTS)
10. Describe the proximate cues and the adaptive causes of insect drift. (8 points)
11. Please compare the depth distribution of net primary productivity between morning, noon, and
afternoon in a shallow, eutrophic lake. (6 points)
12. Describe the succession of algae in the epilimnion of a dimictic lake from early spring to late
fall. Explain what general groups of algae do well at what times of the year and why. (8
points)
13. List and briefly describe the effects on phytoplankton growth of TWO growth control factors
and TWO attrition control factors. (8 POINTS)
14. Describe two density dependent and two density independent controls on stream organisms, and
give an example of how you would test to see which type of control (density dependent versus
density independent) was most important. (10 POINTS)
15. What limits the distribution of aquatic macrophytes? (6 points)
16. How is resource limitation theory used to study the ecology of algae? (8 points)
17. Describe the proximate cues and the adaptive causes of insect drift. (8 points)
18. Describe the differences in effects of invertebrate versus vertebrate predation on zooplankton
communities.
19. Describe at least one possible adaptive cause of cyclomorphosis and give an example of the
effects. (4 points)
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20. In the following graphs, if species A was experiencing a loss rate of 0.1 per day, and species B
was experiencing a loss rate of 0.4 per day, species A would be the superior / inferior /
equal competitor for phosphorus (P). (4 POINTS)
If species A is a diatom, during strong summer stratification the loss rate of species A will
increase / decrease / stay the same, and its population maintenance concentration requirement for
N / P / both N and P will increase / decrease / stay the same. (6 POINTS)
0.7
Species A
0.6
0.5
 (Growth)
0.4
(per day)
0.3
Species B
0.2
0.1
0
0
P (M)
2.0
0.7
Species B
0.6
0.5
 (Growth)
(per day)
0.4
Species A
0.3
0.2
0.1
0
0
N (M)
5.0
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