The Biology Of Soil Health 2

1.

Nematodes consume a variety of different materials including fungi, bacteria and other nematodes.
- A.
  
  True
- B.
  
  False
Correct Answer
A. True

Explanation
As a class of organism, this is true. Nematodes are specialized, however, and some types eat bacteria, others eat fungi, some are predators that eat other nematodes, and some feed on plant roots.

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2.

Which of the following terms means "root zone"?
- A.
  
  Rhizobium
- B.
  
  Mycorrhiza
- C.
  
  Rhizosphere
- D.
  
  Symbiosis
Correct Answer
C. Rhizosphere

Explanation
The word comes from the Greek word for root - "rhizo" and the Old English word "sphere", which originally meant "globe" but has come to mean "area" or "region".

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3.

Which of the following organisms is NOT microscopic?
- A.
  
  Protozoa
- B.
  
  Bacteria
- C.
  
  Fungi
- D.
  
  Micro-arthropods
Correct Answer
D. Micro-arthropods

Explanation
The word "micro" on the front of "Microarthropods" just means "very small" (less than 2 millimeters) and NOT microscopic. Amost all soil arthropods are visible to the naked eye, even though microarthropods like mites and springtails are very tiny.

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4.

Which of the following organisms do protozoa eat?
- A.
  
  Nematodes
- B.
  
  Bacteria
- C.
  
  Micro-arthropods
- D.
  
  Earthworms
Correct Answer
B. Bacteria

Explanation
Protozoans in soil generally eat bacteria, although they may also eat other (smaller) protozoa, soluble organic matter, and occasionally fungi.

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5.

Which of the following organisms are always single-celled?
- A.
  
  Protozoa
- B.
  
  Nematodes
- C.
  
  Fungi
- D.
  
  Earthworms
Correct Answer
A. Protozoa

Explanation
All of the organisms listed among the potential answers above are eukaryotes. This means that the cells of their bodies have nuclei and a higher level of organization than do prokaryotes (bacteria and archaea). However, the only organisms in this group that are ALWAYS single-celled are the protozoa. Nenatodes and earthworms are always multi-celled and fungi can be single-celled (e.g., yeast) but are usually multi-celled.

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6.

Bacteria are less than one micron in width, and no more than a few microns in length. What is a micron?
- A.
  
  One thousandth of a metre
- B.
  
  One hundredth of a metre
- C.
  
  One millionth of a metre
- D.
  
  One thousandth of a centimetre
Correct Answer
C. One millionth of a metre

Explanation
One millionth of a metre is a ten-thousandth of a centimetre, or one thousandth of a millimetre.

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7.

Mycorrhizal fungi do not get their energy from organic residues, but rather from a plant ________.

Correct Answer
root, host

Explanation
As mutualists, mycorrhizal fungi cannot survive without a "host", which comes in the form of a plant "root". They form an attachment with the root through which they exchange water and nutrients in return for carbon-rich substances (photosynthate).

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4
8.

Plants convert the energy of sunlight into biochemical energy via which process?
- A.
  
  Symbiosis
- B.
  
  Pyrolysis
- C.
  
  Photosynthesis
- D.
  
  The photoelectric effect
Correct Answer
C. Photosynthesis

Explanation
Photosynthesis is the fundamental process of converting the sun's energy into biochemical energy, in the form of sugars. Plants (and a few other organisms, such as algae and some microorganisms) are able to use the sun's energy to break down carbon dioxide from the atmosphere (CO2) and water (H2O) and to use the carbon and hydrogen this liberates to synthesize sugars, which then become the building blocks for many organic compounds. Living organisms use the energy embodied in these organic molecules to drive their metabolisms.

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9.

Both bacteria and fungi can be classified into groups by how they obtain their energy. Which of the following terms does NOT describe such a group?
- A.
  
  Decomposers
- B.
  
  Synthesizers
- C.
  
  Mutualists
- D.
  
  Parasites/pathogens
Correct Answer
B. Synthesizers

Explanation
The three categories are "decomposfrers", "mutualists", and "parasites/pathogens". Decomposers get their energy from consuming dead organic materials; mutualists get their energy through excahnges with living organisms; parasites get their energy from attacking living organisms.

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10.

C
- A.
  
  Biological glues
- B.
  
  Frequent ploughing
- C.
  
  High moisture levels
- D.
  
  High fertility levels
Correct Answer
A. Biological glues

Explanation
Biological glues are produced by several organisms, including bacteria, fungi, and earthworms. These glues are the substances that allow particles of sand, silt, clay or organic matter to stick together in clumps. These clumps are a key factor in soil aggregation. Frequent ploughing breaks up aggregates and adds oxygen to the soil, promoting high populations of decomposer microbes that can consume the glues and destroy the aggregates. High moisture or fertility levels can affect aggregation over time, but unless these factors are extreme, they are not key to the process of aggregate formation.

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11.

Which of the Domains of Life do fungi belong in?
- A.
  
  Archaea
- B.
  
  Prokaryotes
- C.
  
  Eukaryotes
- D.
  
  Animalia
Correct Answer
C. Eukaryotes

Explanation
Fungi are eukaryotes, which means that their cells have nuclei and a high level of organization. Prokaryotes (bacteria, archaea) are single-celled organisms with no nuclei and little internal organization. Animalia is a kingdom (animals) within the domain of Eukaryota.

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12.

Which of the following is NOT a basic soil health principle?
- A.
  
  Turn the soil often to keep it loose and friable
- B.
  
  Keep live roots in the ground as much as possible
- C.
  
  Keep the soil covered
- D.
  
  Promote diversity
Correct Answer
A. Turn the soil often to keep it loose and friable

Explanation
Turning the soil is actually the opposite of a main soil-health principal -- "minimize soil disturbance". Turning the soil has immediate benefits, including increased nutrient availability, weed suppression, and looser soil for planting. However, over the longer term, turning the soil promotes soil compaction and is detrimental to some of the soil food web organisms, especially fungi. The latter are key to longer-term aggregate formation and stability, as well as higher levels of soil organic matter.

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13.

Which of the following statements is correct?
- A.
  
  The only way to sequester carbon in soils is to add organic matter such as plant residues.
- B.
  
  Soils have lost so much carbon that they now hold less than the biosphere.
- C.
  
  Soils hold more carbon than the atmosphere and biosphere combined.
- D.
  
  Soil organisms release carbon (respiration) and are not involved in sequestering it.
Correct Answer
C. Soils hold more carbon than the atmosphere and biosphere combined.

Explanation
Although scientists believe that soils have lost a lot of organic matter over the past 10,000-15,000 years, due to agricultural practices such as clearing the land and ploughing, they still hold more carbon than the atmosphere and the biosphere (the sum of all living things) combined. Because they have lost so much carbon, many people think that they can become an important "sink" (storage area) for carbon in the future, thus helping in the fight against climate change. Soil organisms play an important role in carbon sequestration. They do release carbon back into the atmosphere as CO2 (they "breathe" just as we do), butb they also help to hold carbon in the soil through their work in forming soil aggregates, which can trap carbon and protect it from fast release. Carbon builds in soils if it is released more slowly than it is absorbed, and the best management practices associated with soil health either increase carbon intake, slow its release, or both.

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14.

Almost all of the carbon sequestered in soil comes from plant residues .
- A.
  
  True
- B.
  
  False
Correct Answer
B. False

Explanation
It used to be thought that the carbon sequestered in soil came almost entirely from crop residues. While it is true that these residues do boost carbon sequestration, the latest thinking is that much of the carbon sequestered actually comes from plant roots -- either as exudates (carbon-rich substances released into the soil by plant roots for a variety of purposes) or as root residues.

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15.

Plants release carbon-rich substances from their roots (called "exudates"). These serve many purposes, one of which is the creation of "microbiomes" in their root zones.
- A.
  
  True
- B.
  
  False
Correct Answer
A. True

Explanation
A "microbiome" is simply a population of organisms in a given environment (in this case, the rhizosphere, or root zone). There is growing evidence that plants release exudates designed specifically to attract and grow certain types of microbes, so as to create a distinctive microbiome. The purpose of this is to have a population of microbes nearby that will help the plant prevent or fight diseases and pests, optimize nutrition, and generally support plant health. This has a parallel in human (and animal) health, where medical scientists are growing more and more interested in the potential of the human gut microbiome to prevent and cure disease.

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The Biology Of Soil Health 2

Nematodes consume a variety of different materials including fungi, bacteria and other nematodes.

Which of the following terms means "root zone"?

Which of the following organisms is NOT microscopic?

Which of the following organisms do protozoa eat?

Which of the following organisms are always single-celled?

Bacteria are less than one micron in width, and no more than a few microns in length. What is a micron?

Mycorrhizal fungi do not get their energy from organic residues, but rather from a plant ________.

Plants convert the energy of sunlight into biochemical energy via which process?

Both bacteria and fungi can be classified into groups by how they obtain their energy. Which of the following terms does NOT describe such a group?

C

Which of the Domains of Life do fungi belong in?

Which of the following is NOT a basic soil health principle?

Which of the following statements is correct?

Almost all of the carbon sequestered in soil comes from plant residues .

Plants release carbon-rich substances from their roots (called "exudates"). These serve many purposes, one of which is the creation of "microbiomes" in their root zones.