Name_______________________
Agronomy 485/585
Test #1
October 2, 2014
Part I. Circle the one best answer (2 points each).
1.
The most important microbial group in promoting soil structure likely is the __________.
a) actinomycetes b) algae c) bacteria d) fungi e) yeasts
2.
This element is very common in soil but is not a common element in living tissue.
a) nitrogen b) phosphorus c) aluminum d) calcium e) zinc
3.
In ecological terms, which of these best describes a niche?
a) organisms oxidize sulfur
b) organisms tolerate pH of 3.0
c) organisms only live under high temperate conditions
d) organisms require purine for growth
e) organisms can obtain C from inorganic sources
4.
The very coarse sand fraction of soil is as large as 2.00 mm in diameter. A soil bacterium may
be 2.00 μm in diameter. How many bacterial cells when packed adjacent to each other will fit
across a sand particle?
a) 1
b) 100
c) 1,000
d) 10,000
e) 1,000,000
5.
Indicate the best single reason why soil microbiologists, in describing the suitability of soil for
microbial growth, relate moisture contents on a tension basis.
a) it converts easily to percentage H2O by weight
b) it relates directly to the ease at which organisms can move in soil H2O films
c) it relates to the metabolic availability of H2O
d) it is needed in order to conduct plate counts of microbes
e) it relates most directly to the ease of O2 movement through soil
6.
If a soil contains 1,000 kg/ha of fungal biomass, identify the correct statement of expectations.
a) root biomass is expected to be about 1,000 kg/ha
b) earthworm biomass is expected to be about 2,000 kg/ha
c) all other biomass in the soil is expected to equal about 1,000 kg/ha
d) algal biomass is expected to be about 500 kg/ha
e) bacterial biomass is expected to be about 800 kg/ha
7.
This group of organisms uses inorganics for both carbon and energy sources.
a) chemoautotroph
b) chemoheterotroph
c) photoautotroph
d) photoheterotroph
e) autoheterotroph
8.
Five bacteria with a generation time of 30 minutes would produce _______ cells after 2 days
of logarithmic growth.
a) 1 x 962
b) 5 x 3010
96
c) 1 X 5
d) 5 x 248
e) none of these answers is correct.
9.
What is the expected thickness of the water film surrounding an individual soil particle when
the soil-moisture tension is at 1/3 bar (field capacity)?
a) 0.01 µm b) 0.1 µm c) 1.0 µm d) 10.0 µm e) none of these is correct
10.
Identify a suspected difference between mull and mor horizons.
a) The mull horizon is expected to be associated with coniferous forests, whereas the mor
horizon is not.
b) The base content is expected to be higher in coniferous forest vegetation than in grass
vegetation.
c) Faunal activity is expected to be greater associated with the mull horizon than with the mor
horizon.
d) The boundary with the mull horizon is expected to be more distinct than with the mor
horizon.
11.
With time, concentrations of this gas are apt to be most variable from one soil to the next soil.
a) argon
b) hydrogen
c) oxygen
d) nitrogen
e) helium
12.
Which of these words is plural?
a) fungus
c) Bacillus spp.
e) spore
b) bacterium
d) conidium
13.
Which of these forms of carbon is completely oxidized?
a) CH3OH
b) CH4
c) CH3CH2OH
d) CH2O
e) CO2
14.
This fraction of soil organic matter is extractable with alkali and insoluble in acid.
a) water insoluble but alcohol soluble
b) humic acid
c) water soluble
d) fulvic acid
e) humin
15.
According to your reading, a constitutive enzyme is:
a) maintained at a constant level.
b) increases when appropriate substrate is present.
c) decreased at higher temperatures.
d) is unaffected by pH.
e) one that doesn’t require a cofactor.
16.
Identify the true statement concerning a Gram stain.
a) a means of distinguishing between two main groups of fungi
b) a Gram-positive stain is pink
c) a Gram-negative cell wall is more complex (more components) than the Gram-positive cell
wall
d) stains the cell membrane differently whether positive or negative
e) Gram negative cells are normally larger than Gram positive cells
2
17.
Your reading discusses “white-rot” fungi as being organisms that:
a) produce white hyphae during degradation.
b) degrade lignin leaving white cellulose behind.
c) fix nitrogen from the atmosphere using a white-colored enzyme.
d) produce white scales on herbaceous plants.
e) produce white mushroom fruiting bodies when growing in the soil.
18.
Nocardiaceae is a _________.
a) family
c) genus
e) class
b) order
d) tribe
19.
Penicillium is a common fungus isolated from soil and:
a) produces sexual spores on basidia.
b) produces aseptate hyphae.
c) produces ascospores.
d) produces asexual conidia.
e) produces only vegetative hyphae.
20.
Most antibiotics isolated from soil organisms are produced by:
a) Gram-negative bacteria.
b) actinomycetes.
c) anaerobic bacteria.
d) Gram-positive bacteria.
e) fungi.
21.
When 18.4 g oven-dry soil is added to a 90-mL dilution blank, the expected resulting volume
is:
a) 108.4 mL
b) 99.4 mL
c) 96.9 mL
d) 94.6 mL
e) none of these answers is within 0.5 mL
22.
Actinomycetes in a broad sense can be classified as:
a) Gram + bacteria.
b) small eukaryotic fungi.
c) Gram - fungi.
d) Gram + archaea.
e) Gram - archaea.
23.
This individual was a major research worker in the early-to-middle 1900s, but is likely best
known (Nobel Prize) for the work done on antibiotics in his laboratory by one of his graduate
students.
a) Pasteur
b) Lohnis
c) Beijerinck
d) Waksman
e) Starkey
24.
Members of this group are known for nitrogen fixation.
a) Frankia
b) Bacillus
c) Aspergillus
d) Nitrosomonas
e) Pseudomonas
25.
What is meant by "isoelectric pH"?
a) the pH at which the net charge is zero
b) the pH in the soil before H2O is added
c) the pH as measure in 0.01 M CaCl2
d) the pH where organisms best grow in a given environment
e) the soil pH where the H+ concentration doesn't change when temperature changes
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Part II. Short answer and essay. Be to the point in your responses (possible points are indicated in the
left-hand column).
26.
In reading, you come across the terms electron donors and electron acceptors. Explain these
terms and their importance in biological systems. Give examples of each.
(7)
27.
Your text discusses (and we discussed in lecture) Basidiomycota. Briefly explain your
understanding of members of this group.
(6)
28.
One way of characterizing a ‘healthy soil’ is to have a soil with high microbial diversity. Give
advice to a grower on how to manage soil to do this.
(8)
4
29.
Your lab partner is having trouble understanding dilution problems (you’re not surprised based
on all the questions asked this semester). Help your partner understand, after working through
a dilution problem as we have done in this course, why the numbers of organisms found on
the final dilution relate to numbers per gram dry soil.
(6)
30.
You have just renamed an actinomycetal species that had previously be discovered,
characterized, and named by Loynachan. Name a species (create one) that would have an
appropriate genus, specific epithet, and authority for this mythical organism (also specify
percentage royalties allotted to Loynachan).
(6)
31.
Explain how Nitrosomonas gets energy from ammonium. Where does this organism get its
carbon?
(6)
5
32.
What are at least three (3) differences and/or similarities between bacterial endospores and
fungal conidia?
(6)
33.
Why is a waterlogged soil usually considered to be an anaerobic soil? Is this necessarily a
good generalization? Discuss.
(5)
6