Name_______________________
Agronomy 485/585
Test #2
November 6, 2014
Part I. Circle the one best answer (2 points each).
1.
The process of converting substrate carbon to protoplasmic carbon is known as:
a) mineralization.
b) sublimination.
c) denitrification.
d) assimilation.
e) aminization.
2.
Bacteria are one of the most important food groups for:
a) actinomycetes and algae.
b) yeasts and protozoa.
c) springtails and mites.
d) nematodes and mites.
e) protozoa and nematodes.
3.
Which of these compounds has β,1-4 linkages between adjacent glucose units?
a) amylose
b) inulin
c) cellulose
d) chitin
e) starch
4.
This group of organisms has both prokaryotic and eukaryotic members.
a) nematodes b) algae c) protozoa d) rotifers e) fungi
5.
Above what minimum level of N in residue would you expect mineralization to always occur?
a) 0.5%
b) 0.9%
c) 1.2%
d) 1.8%
e) 2.2%
6.
A gardener has recently added earthworms to a new garden plot, and was told that adding
nitrogen would be beneficial to them. The gardener finds different forms of nitrogen available at
the local cooperative. Which should be added?
a) liquid nitrogen (UAN)
b) (NH4)2SO4
c) anhydrous ammonia
d) Ca(NO3)2
e) all sources have equal merit
7.
A rising water table in soil is often detrimental for soil fauna because:
a) there are poor energy sources available in flooded soil.
b) there are few trapped air pockets in flooded soil.
c) the available N has leached away in flooded soil.
d) the microorganisms upon which they live are absent in flooded soil.
e) phosphorus becomes unavailable in flooded soil.
8.
Explain to a friend what is meant by carbon oxidization.
a) the C gains water
b) the C loses water
c) the C gains electrons
d) the C loses electrons
e) the C is fermented
9.
One means of identifying microorganisms is called FAME, which is based on:
a) lipid composition of membranes.
b) 16s DNA.
c) substrate utilization.
d) position in the food chain.
e) nutritional requirements for amino acids in the surrounding environment.
10.
This is recognized as an ecological antagonistic relationship between two organisms in an
environment in which one organism produces a toxin that inhibits the second.
a) mutualism
b) predation
c) synergism
d) protocooperation
e) ammensalism
11.
Of the protozoa, which are smallest and most abundant in soil?
a) cyanophyta
b) flagellates
c) ciliates
d) amoebae
e) zooplankton
12.
The cyst of a Soybean Cyst Nematode contains:
a) eggs.
b) juveniles.
c) the female ovaries.
d) mature adults in a resting sack that later mate and produce offspring.
e) the digestive organelles of the organism.
13.
This structure is the site of nitrogen fixation in cyanobacteria.
a) alkinetes b) nitrogenase c) heterocyst d) nitrocyst e) conidia
14.
Identify the true statement concerning chitin.
a) decomposed mainly by fungi
b) found mostly in tree bark
c) contains N and C
d) contains S and C
e) is a carbohydrate
15.
Why do you suspect there is more biomass generated during aerobic metabolism than during
anaerobic metabolism?
a) the oxygen element makes up a major component of the biomass
b) oxygen can partially substitute for water in the living matter generated
c) more energy is available from substrate utilization aerobically
d) not all of the end products are metabolized aerobically
e) more carbon is available in an anaerobic environment for reduction
16.
Your reading suggests that multiplication of viruses specific to a certain group of microbes might
be used to verify that group members are active in the soil environment because:
a) the viral particles use host growth factors for independent reproduction.
b) as the bacteria die, specific metabolites are released into the environment that enable viruses
to grow.
c) the bacteria consume the viruses as they grow and reproduce.
d) the host must have sufficient metabolic activity for the viral particles to reproduce.
e) viruses are chemoheterotrophs.
17.
Approximately how much N would be required to accommodate 40 mg of C in bacterial
biomass?
a) 3 mg
b) 5 mg
c) 6 mg
d) 8 mg
e) 13 mg
2
18.
Another name for the Chlorophyta is:
a) mastigophora. b) sarcodina. c) soybean cyst nematodes. d) green algae. e) diatoms.
19.
Earthworms are hermaphroditic, which means they:
a) give birth to live young.
b) reproduce by eggs.
c) are all female.
d) are all male.
e) each contain both male and female organs.
20.
Of the compounds listed, which would you expect to degrade the slowest?
a) cellulose b) fats c) hemicellulose d) sugars e) starch
21.
Your reading discusses that the dominant chitin degraders in soil appear to be:
a) bacteria. b) fungi. c) protozoa. d) mites. e) actinomycetes.
22.
Identify the true statement concerning the carbon cycle.
a) the atmosphere contains about 21% carbon dioxide
b) plants are the main consuming organisms in soils on planet Earth
c) carbon dioxide in the atmosphere is being reduced by the burning of fossil fuels
d) microbes are thought to produce about 85% of carbon dioxide in the atmosphere
e) most residue carbon that enters soil is converted to soil humus.
23.
Under anaerobic conditions, possible end-products of glucose metabolism are:
a) organic acids but no CO2.
b) CO2.
c) CH4, alcohols, and organic acids.
d) CO2, CH4, alcohols, and organic acids.
e) CH4.
24.
The most abundant organic compound on planet Earth is presumably:
a) proteins b) cellulose c) starch d) lignin e) chitin
25.
Uronic acids are a component of:
a) celluloses b) starches c) hemicelluloses d) proteins e) lignins
Part II. Short answer and essay. Be to the point in your responses (possible points are indicated in the
left-hand column).
26.
Explain to a University of Iowa graduate which group of organisms tend to dominate in soils
that are moist, have a good mineral nutrition, and high light intensity. Why?
(7)
3
27.
Earthworm casts have been shown to be richer in nutrients than the soil from which the worms
originate. Can adding earthworms to soil be used as a source of fertilizer for higher plants?
Explain
(6)
28.
What are lichens? What features allow lichens to early colonize recently deposited parent
material such as a lava flow.
(6)
29.
Farmer Bob has noticed his soybeans look pale and unhealthy. He examines plant roots and
sees some nodules on the root surface that are red inside, and some embedded nodules that
are white inside. What is he seeing? How could he grow healthier plants next year?
(6)
30.
Composting involves many of the soil/microbial factors we discussed this semester. Explain:
a) what is the process of composting.
(5)
b) how one determines when the composting process is complete.
(5)
4
c) the conditions when N might be added to compost and when it likely is not needed.
(5)
31.
(6)
Explain to a University of Iowa graduate why lignin is so difficult to degrade.
33.
This is a philosophical question. DNA evidence for soil suggests organisms exists that we are
not observing on plate cultures. Should we call these ‘unculturable’ or ‘uncultured’ organisms?
Explain.
(4)
5