Below are listed several examples of the types of questions that may appear on Limnology exams. Use these questions as an aid to guide your studying. This is by no means a complete list of all possible questions or topics covered, so don't assume that if you know the answers to these questions that you have a lock on that "A". Please refer to your reading assignments and lecture notes for the complete range of potential topics to be tested on each exam.


EXAM #1

Essay Question examples

Compare the geographic distributions and seasonal temperature cycles of dimictic and cold monomictic lakes.

How are the various wavelengths of light affected by the process of light attenuation in lakes?

How does light attenuation affect photosynthesis within a water column?

Describe movements of water within a water column as travelling surface waves approach and pass.

Describe how the structure of a water molecule and hydrogen bonding produce surface tension.

How does water density change between -1 C and 20 C?

Describe and compare two types of tectonic lakes.

How are levee lakes and oxbow lakes formed?

What kinds of lakes can be produced by glaciers?

Describe how the amount of sunlight entering a lake changes as the angle of incidence changes.

What is a Langmuir spiral and how does it move lake water?

What happens to a deepwater travelling surface wave as it approaches the lakeshore?


Terminology/definition examples

cirque
caldera
graben
cenote
Secchi disk
1% light transmittance

epilimnion

metalimnion

hypolimnion

thermocline
amictic

ripple
plunging breaker
fetch
uninodal seiche


EXAM #2

Essay Question examples

What type of oxygen profile is typical of a stratified, eutrophic lake? Why?

What is responsible for causing positive and negative heterograde oxygen profiles within a lake during summer?

What does agressive CO2 do in a lake?

Describe the buffer system at work in Lake Winona.

Why is summerkill of fish related to daily cycles in oxygen concentration within a lake?

Describe the biological and physical competition for ammonia and nitrate in a lake.

How does iron affect phosphate abundance in a lake's epilimnion and hypolimnion?

Draw a depth versus total phosphorus diagram for Lake Winona in August (no oxygen in the hypolimnion).

How does alkalinity differ from hardness and salinity?

What role can molybdenum (or lack of it) play in nitrogen concentrations within a lake?

When are diatoms most abundant in temperate lakes? What physical factors are most important in controlling diatom abundance?

Describe the relative rates of primary production of the three major primary producers in lakes and explain what factors are responsible for differences in these rates among the three groups.

What are gas lacunae and how do they limit the depth distribution of submersed macrophytes?

What are the primary roles of the two general categories of sediment bacteria? Which group is directly responsible for the process of internal fertilization within eutrophic lakes?

Why doesn't acid rain falling into Lake Winona affect the lake's pH?

How do phytoplankton populations affect the depth of the euphotic zone as lake productivity increases (oligotrophic to hypereutrophic)?

How do leaves of emergent and submersed macrophytes differ and why?

Why do photosynthesizing macrophytes in Lake Winona develop marl deposits on their leaf surfaces?

Why can photosynthesis (or lack of it during the dark) induce pH shifts in a lake without a buffering system?

Terminology/definition examples

aggressive CO2

marl
cyclomorphosis
cyanobacteria
alkalinity
photoinhibition
self-shading

nitrification
denitrification
profundal

pelagial

littoral
buffer system
orthograde

clinograde
positive heterograde

oligotrophic

mesotrophic

eutrophic

hypereutrophic


EXAM #3

Essay Question examples

Which groups of zooplankton in temperate lakes display seasonal polymorphisms and why?

Explain the process of reproduction in rotifers, cladocerans, and copepods.  How are they similar?  Different?

Describe the vertical migrations undertaken by two groups of zooplankton and explain the rationale for such movements.

What factors most affect the abundance and distribution patterns of benthic invertebrates in lakes?

Compare and contrast the littoral-zone benthos with the profundal-zone benthos. How do they differ? What is a typical profundal benthic invertebrate assemblage in a eutrophic versus an oligotrophic lake?

Describe how benthic invertebrate diversity and biomass change from the littoral zone through the sublittoral zone and to the profundal zone of a moderately productive lake.

What are the stressful conditions faced by profundal benthos during summer stratification in a eutrophic lake?  How do different types of invertebrates cope with these conditions?

Describe the four categories of fish based on their feeding relationships.

How can a large population of common carp negatively impact a entire lake ecosystem?

How does fish productivity in temperate lakes compare to that in temperate rivers and streams? In tropical lakes?

Describe the process of lake succession. What "stage" of the process requires the most time and why?

Compare/contrast various physical, chemical, and biological characteristics of a lake early (e.g., oligotrophic) and late (eutrophic) in the successional process.

What happens to a lake during littoral encroachment, and how does it complete the final stages of lake succession?

What causes cultural eutrophication, what effects does it have on the lake ecosystem, and how was the process reversed in Lake Erie?

Describe four reasons why wetlands are important aquatic habitats.

How does the physical nature of a lotic system change between its headwaters and its mouth, and how do these changes affect phytoplankton, benthic invertebrates, and fish communities?

Compare phytoplankton/zooplankton in lakes and rivers.

What is the longitudinal zonation of invertebrates and fishes in lotic systems?

Compare and contrast the physical conditions present in the three longitudinal zones of a typical, large mainstream storage reservoir.

Describe four characteristics of a typical, mainstream run-of-river reservoir.

Terminology/definition examples

corona

kairomone

polymorphism

carapace

parthenogenesis
ephippium
nauplius
copepodite

calanoid

cyclopoid
standing crop
phantom midge
benthivores

eutrophic

hypereutrophic
swamp
marsh
bog

erosional

depositional
boundary layer
frazil ice


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Neal D. Mundahl
Department of Biology
Winona State University
Winona, Minnesota