Organisms that use energy from the sun to manufacture their organic carbon compounds are ___. - ANSWERAutotrophs
I exist in a symbiotic relationship with plant roots. I get sugars from the plants in exchange for nutrients, particularly P andZn, and water. However, I cannot fix nitrogen from the ...
SCSC 301 Exam 2 Questions &
Answers 100% Correct!!
Organisms that use energy from the sun to manufacture their organic carbon
compounds are ___. - ANSWERAutotrophs
I exist in a symbiotic relationship with plant roots. I get sugars from the plants in
exchange for nutrients, particularly P andZn, and water. However, I cannot fix
nitrogen from the atmosphere. Sometimes I am able to protect my host from other
plant pathogens. To do this, sometimes I produce antibiotics. What am I? -
ANSWERMycorrhizae
I am found in most soils, but I am particularly partial to sandy soils. I am
unsegmented and 4 to 100 mm across. Most of my kindfeed on just about all the
other kinds of organisms from tiny up to insect larvae and plant roots. Some of my
kind can be used as biological controlagents to control pests (e.g., corn rootworm).
Others of my kind are considered plant parasites (e.g., in cotton and peanut). I can
survive by a cryptobioticstate when times are bad so that I can survive almost any
climate. What am I? - ANSWERNematode
Which of the following is LEAST critical for the growth of microorganisms? -
ANSWERday length
Which term best describes the transformation of C and nutrients from organic forms
to plant available inorganic forms? - ANSWERMineralization
Which of the following do soil organisms play a role in?
a)Organic matter decomposition
b)Degradation of toxins and foreign chemicals
c)Transformations of nutrients
d)All of the above
e)None of the above - ANSWERd)All of the above
Which of the following are NOT considered fungi? - ANSWERActinomycetes
Which of the following describes the rhizosphere? - ANSWERZone around the roots
that is influenced by the roots activities (e.g., exudation and sloughed cells) and that
is typically hosts a large microbial population
Which of the following is NOT a carbon-containing compound that is involved in the
cycling of carbon associated with most plant/animal life forms? - ANSWERCalcium
carbonate
______fixation is a very important function of organisms in soils. - ANSWERNitrogen
The most important decomposers of residue in soils in the pH range of 4 to 5.5 are: -
ANSWERFungi
, A principal role of organisms in soils is the formation of: - ANSWERHumus
Which organic matter property affects the availability of nutrients to plants? -
ANSWERCation exchange capacity
Complete degradation of residues (complete oxidation) results in _______ -
ANSWERCO2
Which of the answers below represents an immobilized form of N? -
ANSWERProtein in a bacterial cell
Which is true when comparing aerobic vs anaerobic organic matter decomposition? -
ANSWERAnaerobic degradation is much slower than aerobic and results in
compounds that are partially decomposed
Soil organic matter degradation will be greatest when_____________ -
ANSWERThere is sufficient soil moisture and aeration at neutral pH and relatively
warm temperatures to degrade residue with high levels of N
Organic matter tends to decrease the ___ of soils. - ANSWERbulk density
___ is the element in residue that has the greatest effect on the rate of residue
decomposition. - ANSWERNitrogen
The organic matter content of soils tends to decrease with increasing frequency of: -
ANSWERcultivation
A soil with C/N ratio of 600:1 could be a material such as_______ -
ANSWERsawdust or leaves that have a low N content and a high potential for N
immobilization
As water is adsorbed by a dry soil, the soil matric potential of the dry soil ______. -
ANSWERincreases
Water moves downward in a profile from the A horizon (sandy loam) to the B horizon
(loam)_____. - ANSWERas soon as the wetting front reaches the B horizon
Evaporation losses of water from soils may be reduced by: - ANSWERcrop residue
on the surface
Poorly defined organic substances that are complex, resistant to decay, and
polymeric are ___ - ANSWERHumic substances
Which of the following could be used to improve soil organic matter in a cropping
system? - ANSWERReduce the plant materials that are harvested and return any
residues back to the field
If you had to guess, which environment would likely have the greatest soil organic
matter? - ANSWERNortheast US
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