Agricultural Education (Grades 5–12)
Subtest 1 Sample Items
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Question 1
1. After an agricultural field is left fallow or a fire destroys the vegetation in an area, plant species
that dominate the early stages of succession will most often be characterized by:
- delayed maturity and production of a small number of large, well-developed seeds.
- deep root systems that bring nutrients and water from the lower levels of the soil and subsoil.
- quick germination of seeds, rapid vegetative growth, and relatively short life spans.
- tolerance of a wide range of environmental conditions such as shade and drought.
Answer to question 1
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0001) This ecosystem is characterized
by an abundance of light, usually temporary abundance of nutrients, and, most importantly, an absence
of competition. Under these conditions, plants that germinate and grow quickly, mature rapidly, and
produce a large number of seeds will get a head start on and be able to outcompete slower growing, longer-lived
plants. Once the ground is colonized with these "weed" species, competition for light, water, and nutrients
increases, and plants that are slower growing, that are more tolerant of shade, and that produce a smaller
number of higher-quality seeds are better able to compete.
Correct Response: C. (Objective 0001) This ecosystem is characterized by an abundance
of light, usually temporary abundance of nutrients, and, most importantly, an absence of competition.
Under these conditions, plants that germinate and grow quickly, mature rapidly, and produce a large
number of seeds will get a head start on and be able to outcompete slower growing, longer-lived plants.
Once the ground is colonized with these "weed" species, competition for light, water, and nutrients
increases, and plants that are slower growing, that are more tolerant of shade, and that produce a smaller
number of higher-quality seeds are better able to compete.
Question 2
2. Tracheids are long, dead cells that conduct water and provide structural support in some plants and
are located in which of the following tissues?
- xylem
- epidermis
- phloem
- cork cambium
Answer to question 2
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0001) Xylem is a structurally
complex tissue that conducts water and dissolved minerals from the roots to all parts of the plants.
Tracheids are elongated, dead cells in the xylem that conduct water through pits in the cell. The main
force moving water upward through the tracheids is capillary action due to removal of water through
the leaves by transpiration.
Correct Response: A. (Objective 0001) Xylem is a structurally complex tissue that
conducts water and dissolved minerals from the roots to all parts of the plants. Tracheids are elongated,
dead cells in the xylem that conduct water through pits in the cell. The main force moving water upward
through the tracheids is capillary action due to removal of water through the leaves by transpiration.
Question 3
3. Which of the following is one characteristic of members of the grass family that distinguishes them
from most other flowering plants?
- Grasses use both C3 and C4 methods of photosynthesis, and individual plants can
switch between the two.
- The meristems of grasses lie at the bases of each stem between the leaves rather than at the tips of
the shoots.
- Taproots are rarely present in grasses, which confines them to areas where sufficient surface moisture
is present.
- Grasses are able to reproduce asexually from corms or rhizomes as well as sexually by the formation
of seeds.
Answer to question 3
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0001) The grasses are a large
and important family of monocot plants. One major difference between grasses and other families of flowering
plants is the location of the meristem tissues from which new leaves, or blades, grow. In most plants,
the meristems are located at the tips of the shoots and plants grow from these points. In grasses, these
tissues are located at the base of the leaves. This is an adaptation to grazing animals and fire, because
the meristem is protected even if the upper parts of the blades are destroyed, allowing the plant to
quickly resume growth.
Correct Response: B. (Objective 0001) The grasses are a large and important family
of monocot plants. One major difference between grasses and other families of flowering plants is the
location of the meristem tissues from which new leaves, or blades, grow. In most plants, the meristems
are located at the tips of the shoots and plants grow from these points. In grasses, these tissues are
located at the base of the leaves. This is an adaptation to grazing animals and fire, because the meristem
is protected even if the upper parts of the blades are destroyed, allowing the plant to quickly resume
growth.
Question 4
4. Plants obtain which of the following elements from the air during the process of photosynthesis?
- hydrogen
- oxygen
- nitrogen
- carbon
Answer to question 4
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0001) Photosynthesis is the
process through which plants use sunlight to produce glucose composed of carbon, hydrogen, and oxygen.
Plants obtain the hydrogen and oxygen from water and the carbon from carbon dioxide in the atmosphere.
Correct Response: D. (Objective 0001) Photosynthesis is the process through which
plants use sunlight to produce glucose composed of carbon, hydrogen, and oxygen. Plants obtain the hydrogen
and oxygen from water and the carbon from carbon dioxide in the atmosphere.
Question 5
5. Breaking seed dormancy in many species of plants is controlled primarily by which of the following
plant hormones?
- auxins
- gibberellins
- abscisic acid
- ethylene
Answer to question 5
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0001) The germination of
seeds usually begins when the seed is exposed to water, and starch in the endosperm is converted to
glucose. Gibberellins in the seed embryo are believed to signal starch hydrolysis by inducing the synthesis
of certain enzymes. The sugar produced can then be used in cellular respiration to produce energy for
the developing seed embryo.
Correct Response: B. (Objective 0001) The germination of seeds usually begins when
the seed is exposed to water, and starch in the endosperm is converted to glucose. Gibberellins in the
seed embryo are believed to signal starch hydrolysis by inducing the synthesis of certain enzymes. The
sugar produced can then be used in cellular respiration to produce energy for the developing seed embryo.
Question 6
6. Which of the following occurs during the light-independent, or Calvin-Benson, cycle of photosynthesis?
- Energy is captured by the chlorophyll pigment located in the chloroplasts of leaf cells.
- Carbon dioxide is captured and combined with ATP, NADPH, and hydrogen to form sugars.
- Hydrogen is produced by splitting water molecules and used to form ATP and NADPH.
- Oxygen is released as a waste product when carbon atoms are stripped from carbon dioxide.
Answer to question 6
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0001) The Calvin-Benson cycle
of photosynthesis, also known as the C3 cycle, is carried out in the light, but is light-independent.
The cycle uses the products NADPH and ATP that are produced during the light-dependent phase of photosynthesis.
One molecule of CO2 is captured and added to a five-molecule version of CO2, which
is then split into two three-molecule groups by the enzyme RuBisCo using the energy provided by NADPH
and ATP. One three-carbon molecule is used to form three-carbon sugar (G3P), the other uses NADPH and
ATP to capture additional CO2 molecules to form a five-carbon molecule, and the process begins
again.
Correct Response: B. (Objective 0001) The Calvin-Benson cycle of photosynthesis,
also known as the C subscript 3 cycle, is carried out in the light, but is light-independent. The cycle
uses the products N A D P H and A T P that are produced during the light-dependent phase of photosynthesis.
One molecule of C O subscript 2 is captured and added to a five-molecule version of C O subscript 2,
which is then split into two three-molecule groups by the enzyme RuBisCo using the energy provided by
N A D P H and A T P. One three-carbon molecule is used to form three-carbon sugar (G3P), the other uses
N A D P H and A T P to capture additional C O subscript 2 molecules to form a five-carbon molecule,
and the process begins again.
Question 7
7. In a certain type of flowering plant, individual plants that are homozygous for the white allele
produce white flowers. Other plants that are homozygous for the red allele produce red flowers. Heterozygous
plants produce pink flowers. What is the likely ratio of colors if a plant breeder crosses two plants
that have pink flowers?
- 1 white flower and 3 pink flowers
- all flowers would be pink
- 1 white flower, 2 pink flowers, and 1 red flower
- 1 white flower, 1 pink flower and 2 red flowers
Answer to question 7
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0002) The case outlined above
demonstrates the concept of incomplete dominance in alleles. Each heterozygous pink plant has one white
allele and one red allele, shown as WR. The genotypes for the two pink plants are W1R1
× W2R2. The four combinations possible when they are crossed will be W1W2
+ W1R2 + R1W2 + R1R2, which will yield
1 white-flowered plant, 2 pink-flowered plants, and 1 red-flowered plant.
Correct Response: C. (Objective 0002) The case outlined above demonstrates the
concept of incomplete dominance in alleles. Each heterozygous pink plant has one white allele and one
red allele, shown as WR. The genotypes for the two pink plants are W subscript 1 R subscript 1 times
W subscript 2 R subscript 2 . The four combinations possible when they are crossed will be W subscript
1 W subscript 2 + W subscript 1 R sub 2 + R subscript 1 W subscript 2 + R subscript 1 R subscript 2
, which will yield 1 white-flowered plant, 2 pink-flowered plants, and 1 red-flowered plant.
Question 8
8. Sexual reproduction using seeds in vascular plants has which of the following advantages over asexual
reproduction?
- Sexual reproduction produces different combinations of genes, some of which may be better adapted to
changes in the environment.
- The plant embryo within a seed is provided with a substantial source of nourishment to sustain it during
the early stages of its life cycle.
- Seeds are less subject to loss from predation or competition with other individuals than are offspring
produced by asexual reproduction.
- Plants produced from seeds are likely to grow faster and use nutrients more efficiently than those
produced by asexual reproduction.
Answer to question 8
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0002) Since both abiotic
(e.g., temperature) and biotic (e.g., competition) environmental factors are subject to change, plant
populations that exhibit genetic variability are more likely to produce individuals that are adapted
to such changes. Offspring of plants that reproduce asexually are clones and are genetically identical.
An asexually reproducing plant lineage within a population would therefore lack the genetic variability
to adapt to a novel disease or the presence of a new type of predator.
Correct Response: A. (Objective 0002) Since both abiotic (e.g., temperature) and
biotic (e.g., competition) environmental factors are subject to change, plant populations that exhibit
genetic variability are more likely to produce individuals that are adapted to such changes. Offspring
of plants that reproduce asexually are clones and are genetically identical. An asexually reproducing
plant lineage within a population would therefore lack the genetic variability to adapt to a novel disease
or the presence of a new type of predator.
Question 9
9. Which of the following best describes the role of bacterial plasmids in genetic engineering?
- cutting the DNA molecule to remove the desired sequence from the donor cell
- serving as the source for the DNA that will be placed into the host's cell
- stimulating reproduction of multiple clones of the DNA inside the new transgenic cell
- carrying the snippet of DNA from one organism into the cell of a second organism
Answer to question 9
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0002) A plasmid is a small
DNA molecule that is physically separate from, and can replicate independently of, the chromosomal DNA
within a bacterial cell. Modern plasmids have been selected to contain multiple sites where snippets
of DNA can be inserted. The plasmid with the transgenic DNA can then be inserted into the host cell,
which can be cloned, or the transgenic plasmid itself can be cloned and inserted into multiple host
cells.
Correct Response: D. (Objective 0002) A plasmid is a small DNA molecule that is
physically separate from, and can replicate independently of, the chromosomal DNA within a bacterial
cell. Modern plasmids have been selected to contain multiple sites where snippets of DNA can be inserted.
The plasmid with the transgenic DNA can then be inserted into the host cell, which can be cloned, or
the transgenic plasmid itself can be cloned and inserted into multiple host cells.
Question 10
10. A flower grower plants a field with a new flower that is an interspecific cross between two related
species. The grower plans to select the best plants and save their seeds to plant the following year.
By continuing this process over several years, the farmer hopes to have an even better stock of seeds
for planting. Which of the following best describes a likely difficulty with the grower's plan?
- Plants in the first hybrid generation will be too uniform to allow selection of the best individuals.
- Interspecific hybrids usually revert back to one of the parent lines in the second hybrid generation.
- Plants that are interspecific hybrids are almost always sterile without direct genetic manipulation.
- Interspecific hybrids are usually less vigorous and more difficult to grow than plants from either
parent line.
Answer to question 10
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0002) Interspecific and even
intergeneric hybrids have been produced by fertilizing the ovules of one species with pollen from another
species. Such crosses are often more vigorous due to a higher degree of heterozygosity in the offspring,
a phenomenon called heterosis. However, such crosses are often sterile due to chromosome-pairing difficulties
during meiosis. An exception is triticale, which is a fertile cross between the genus Triticum
(wheat) and the genus Secale (rye).
Correct Response: C. (Objective 0002) Interspecific and even intergeneric hybrids
have been produced by fertilizing the ovules of one species with pollen from another species. Such crosses
are often more vigorous due to a higher degree of heterozygosity in the offspring, a phenomenon called
heterosis. However, such crosses are often sterile due to chromosome-pairing difficulties during meiosis.
An exception is triticale, which is a fertile cross between the genus Triticum (wheat) and
the genus Secale (rye).
Question 11
11. Budding is an asexual method of propagation often used in the apple-growing industry to produce
apples that do not reproduce true from seeds. In order to use budding as a means of propagating these
apples, it is necessary that:
- the xylem and phloem tubes of the scion of the desired variety be aligned with those of the stock.
- the buds of the desired variety be actively growing at, or near, their maximum rate.
- each bud from the desired variety be dusted with auxins to induce root development.
- the cambium layers of both the scion of the desired variety and the stock be in contact.
Answer to question 11
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0002) Budding is a form of
grafting that involves placing a scion, or cutting, from a plant with desired characteristics such as
superior fruit, into the stem, or stock, of a plant with other characteristics such as hardiness or
disease resistance. The cambium is the thin layer of actively growing tissues that produces xylem cells
to the inside and phloem cells to the outside. In order for a graft to be successful, the actively growing
cambium of both the scion and the stock must be in contact.
Correct Response: D. (Objective 0002) Budding is a form of grafting that involves
placing a scion, or cutting, from a plant with desired characteristics such as superior fruit, into
the stem, or stock, of a plant with other characteristics such as hardiness or disease resistance. The
cambium is the thin layer of actively growing tissues that produces xylem cells to the inside and phloem
cells to the outside. In order for a graft to be successful, the actively growing cambium of both the
scion and the stock must be in contact.
Question 12
12. Wheat stem rust is a serious fungal parasite of wheat that can cause heavy crop losses. Recently
a new strain of stem rust has devastated crops in some regions of Africa, and researchers fear that
wheat crops in Minnesota may be vulnerable. Which of the following is likely to be the most effective
way for farmers in Minnesota to minimize losses due to infection of the wheat crop by this new strain
of fungus?
- planting varieties that possess some resistance to the new strain of rust
- destroying wild relatives of wheat that may be alternate hosts for the new strain of rust
- controlling insects that spread the disease
- applying dormant oil spray several times during the growing season
Answer to question 12
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0003) Wheat stem rust was
once one of the most feared diseases of wheat and is still a problem in some areas when new forms of
the parasite evolve and infect the resistant wheat crops that are now grown. The spores are often carried
by insects, wind, or rain from infected volunteer wheat plants or the rust's alternate host, which is
barberry. Elimination of alternate hosts and insects has proven ineffective in controlling rust. Most
genotypes of wheat stem rust have been largely controlled in the major wheat-producing areas of North
America by breeding and planting resistant varieties. This is the most practical way of controlling
the disease because it does not require constant vigilance in removing alternate hosts or preventing
exposure of the growing plants to air-, insect-, or rain-borne spores.
Correct Response: A. (Objective 0003) Wheat stem rust was once one of the most
feared diseases of wheat and is still a problem in some areas when new forms of the parasite evolve
and infect the resistant wheat crops that are now grown. The spores are often carried by insects, wind,
or rain from infected volunteer wheat plants or the rust's alternate host, which is barberry. Elimination
of alternate hosts and insects has proven ineffective in controlling rust. Most genotypes of wheat stem
rust have been largely controlled in the major wheat-producing areas of North America by breeding and
planting resistant varieties. This is the most practical way of controlling the disease because it does
not require constant vigilance in removing alternate hosts or preventing exposure of the growing plants
to air-, insect-, or rain-borne spores.
Question 13
13. In terms of quantity harvested (i.e., number of cords), the most important forest product in Minnesota
is:
- saw logs.
- residential fuel wood.
- pulpwood.
- commercial fuel wood.
Answer to question 13
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0003) When measured by volume,
pulpwood is, by far, the most extensively harvested forest product in Minnesota. Over four times as
many cords of pulpwood are harvested compared with the next most commonly harvested product, saw and
specialty logs.
Correct Response: C. (Objective 0003) When measured by volume, pulpwood is, by
far, the most extensively harvested forest product in Minnesota. Over four times as many cords of pulpwood
are harvested compared with the next most commonly harvested product, saw and specialty logs.
Question 14
14. Soybeans in a field have weak root systems and stalks and older leaves that are mottled, spotted,
or curled, and that often show burned margins. These plants are most likely suffering from a deficiency
of:
- nitrogen.
- potassium.
- iron.
- phosphorus.
Answer to question 14
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0003) Unlike many other nutrients,
potassium does not appear to be an integral part of plant constituents (e.g., protoplasm, carbohydrates,
fats). However, potassium plays a major role in metabolism of other compounds, in regulating opening
and closing of stomata, and in water retention. These roles cause characteristic symptoms when potassium
is deficient, including weak stems and burning of the edges of leaves.
Correct Response: B. (Objective 0003) Unlike many other nutrients, potassium does
not appear to be an integral part of plant constituents (e.g., protoplasm, carbohydrates, fats). However,
potassium plays a major role in metabolism of other compounds, in regulating opening and closing of
stomata, and in water retention. These roles cause characteristic symptoms when potassium is deficient,
including weak stems and burning of the edges of leaves.
Question 15
15. A foliar spray containing Bacillus thuringiensis (BT) would likely be used in Minnesota
to control:
- grasshoppers on wheat.
- aphids on soybeans.
- earworms on sweet corn.
- leafhoppers on potatoes.
Answer to question 15
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0003) Bacilllus thuringiensis
(BT) is a common soil bacteria that was discovered to be a potent endotoxin for certain types of insects.
BT produces a toxic crystal that reacts with the cells lining the gut of susceptible insect species.
BT is most commonly used against members of the order Lepidoptera, such as the corn earworm,
although various strains may be effective against certain other insect pests.
Correct Response: C. (Objective 0003) Bacilllus thuringiensis (BT) is
a common soil bacteria that was discovered to be a potent endotoxin for certain types of insects. BT
produces a toxic crystal that reacts with the cells lining the gut of susceptible insect species. BT
is most commonly used against members of the order Lepidoptera, such as the corn earworm, although
various strains may be effective against certain other insect pests.
Question 16
16. Which of the following correctly describes the flow of a unit of blood through the mammalian circulatory
system, beginning when the deoxygenated blood arrives in the heart through the veins and the vena cava?
- right atrium → right ventricle → lungs → left atrium →
left ventricle → body → right atriumright atrium, right ventricle,
lungs, left atrium, left ventricle, body, right atrium
- left atrium → left ventricle → lungs → right atrium →
right ventricle → body → left atriumleft atrium, left ventricle,
lungs, right atrium, right ventricle, body, left atrium
- right atrium → right ventricle → body → left atrium →
left ventricle → lungs → right atriumright atrium, right ventricle,
body, left atrium, left ventricle, lungs, right atrium
- left atrium → left ventricle → body → right atrium → right
ventricle → lungs → left atriumleft atrium, left ventricle, body,
right atrium, right ventricle, lungs, left atrium
Answer to question 16
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0004) Deoxygenated blood
travels back to the heart from the tissues of the body via the network of veins. Before traveling from
the heart back out to the tissues through the body's arteries, the blood must be reoxygenated. The blood
first flows into the vena cava and from there into the right atrium. It then passes into the right ventricle,
which pumps the deoxygenated blood to the lungs where red blood cells pick up oxygen. The reoxygenated
blood then moves from the lungs back to the left atrium of the heart and into the left ventricle, which
pumps the blood out through the aorta into the network of arteries and finally capillaries where the
oxygen is absorbed by the cells.
Correct Response: A. (Objective 0004) Deoxygenated blood travels back to the heart
from the tissues of the body via the network of veins. Before traveling from the heart back out to the
tissues through the body's arteries, the blood must be reoxygenated. The blood first flows into the
vena cava and from there into the right atrium. It then passes into the right ventricle, which pumps
the deoxygenated blood to the lungs where red blood cells pick up oxygen. The reoxygenated blood then
moves from the lungs back to the left atrium of the heart and into the left ventricle, which pumps the
blood out through the aorta into the network of arteries and finally capillaries where the oxygen is
absorbed by the cells.
Question 17
17. Which of the following is one important difference between the teeth of horses and those of most
grazing ruminants such as sheep and cattle?
- Horses have front teeth in the upper jaw, while most ruminants lack these teeth.
- Horses' molars' surfaces have sharp ridges, while molars of most ruminants are smooth.
- Horses have incorporated the premolars into the front teeth, while most ruminants have not.
- Horses' molars have open roots and are ever-growing, while most ruminant molars have closed roots.
Answer to question 17
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0004) Horses have front teeth
in both upper and lower jaws, while ruminants, except for camels and their relatives, have a horny pad
rather than front teeth in the upper jaw. This leads to greater contact with the lower front teeth and
allows for more efficient nipping of vegetation in ruminants versus non-ruminants, such as horses.
Correct Response: A. (Objective 0004) Horses have front teeth in both upper and
lower jaws, while ruminants, except for camels and their relatives, have a horny pad rather than front
teeth in the upper jaw. This leads to greater contact with the lower front teeth and allows for more
efficient nipping of vegetation in ruminants versus non-ruminants, such as horses.
Question 18
18. Which of the following best explains how horses are efficient grazers that eat foods high in cellulose,
even though they lack the multichambered stomach of ruminants?
- Horses have a very large stomach that can hold enormous quantities of food for long periods of time
while various microbes ferment and break down the cellulose.
- Horses have a very long small intestine through which food travels slowly, giving bacteria in the intestine
time to ferment the food and break down the cellulose.
- Horses have a large pouch called the cecum at the beginning of the large intestine where food is stored
and fermented for up to seven hours by microbial action.
- Horses have a short large intestine through which food travels rapidly so that they can eat a great
deal and absorb enough nutrients without extensive fermentation by microbes.
Answer to question 18
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0004) Horses are known as
hindgut fermenters because they ferment their food using microbial action after it leaves the stomach
and small intestine. The small intestine opens into a large blind-ended pouch, the cecum, which can
hold seven gallons of partially digested food. In the cecum, microbes work to break down the cellulose
that was not digested in the small intestine. The fermented material is then passed into the long large
intestine where carbohydrates from the cellulose are absorbed.
Correct Response: C. (Objective 0004) Horses are known as hindgut fermenters because
they ferment their food using microbial action after it leaves the stomach and small intestine. The
small intestine opens into a large blind-ended pouch, the cecum, which can hold seven gallons of partially
digested food. In the cecum, microbes work to break down the cellulose that was not digested in the
small intestine. The fermented material is then passed into the long large intestine where carbohydrates
from the cellulose are absorbed.
Question 19
19. Use the pedigree given below to answer the question that follows.
Key with four items: black female, black male, red female, and red male. Illustration from top to bottom.
A single horizontal line connects a black female, labeled with the letter X, and a red male. They give
birth to four offspring: a black female, labeled with the letter Y; a red male; a black female; and
another black female. There is an unrelated black male in the same row as the four offspring. The black
male and the black female labeled Y, which are adjacent to one another, are connected with a horizontal
line. They produce three offspring: A black female, another black female, and a black male.
A particular breed of cattle can be either black or red in color. The allele producing black coloration
is dominant to the allele producing red coloration. According to the pedigree shown, the animals marked
X and Y will have which of the following genotypes?
- X is Br, and Y is Br
- X is Br, and Y is BB
- X is BB, and Y is BB
- X is BB and Y is Br
Answer to question 19
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0004) In the diagram a black
female is mated to a red bull. Since the black allele is dominant, the female's genotype can be either
homozygous dominant (BB) or heterozygous (Br). In the F1 generation one of the offspring is red, which
means that that X must be heterozygous (Br). The offspring marked Y must also be heterozygous (Br) since
her father was red and was therefore homozygous recessive (rr).
Correct Response: A. (Objective 0004) In the diagram a black female is mated to
a red bull. Since the black allele is dominant, the female's genotype can be either homozygous dominant
(BB) or heterozygous (Br). In the F1 generation one of the offspring is red, which means that that X
must be heterozygous (Br). The offspring marked Y must also be heterozygous (Br) since her father was
red and was therefore homozygous recessive (rr).
Question 20
20. Which of the following best describes how runoff from agricultural fields typically affects nearby
ponds and small lakes?
- Fish and other aquatic life are killed directly by toxic compounds present in the runoff.
- Nutrients in the runoff cause a phytoplankton bloom that depletes oxygen when phytoplankton die and
decay.
- Herbicide- and pesticide-resistant plants and animals are favored, and biodiversity decreases.
- Nutrients in the runoff cause rapid population growth of all species, resulting in overcrowding and
smaller fish.
Answer to question 20
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0004) Phytoplankton populations
in small lakes and ponds are limited by water temperatures, amount of sunlight, and nutrient concentration.
Agricultural runoff, especially in the spring, raises the nutrient level, especially nitrogen, in local
bodies of waters. This causes rapid population growth of phytoplankton such as algae. Eventually a major
die-off occurs as the nutrients run out and the masses of phytoplankton decay. The process of decay
uses oxygen, which rapidly depletes the oxygen concentration level in the pond or lake. Lack of oxygen
causes fish and much of the other lake fauna, such as aquatic insects, to die, and the lake basically
becomes sterile. This process is called eutrophication.
Correct Response: B. (Objective 0004) Phytoplankton populations in small lakes
and ponds are limited by water temperatures, amount of sunlight, and nutrient concentration. Agricultural
runoff, especially in the spring, raises the nutrient level, especially nitrogen, in local bodies of
waters. This causes rapid population growth of phytoplankton such as algae. Eventually a major die-off
occurs as the nutrients run out and the masses of phytoplankton decay. The process of decay uses oxygen,
which rapidly depletes the oxygen concentration level in the pond or lake. Lack of oxygen causes fish
and much of the other lake fauna, such as aquatic insects, to die, and the lake basically becomes sterile.
This process is called eutrophication.
Question 21
21. The primary reason for inbreeding in a line of dairy cattle generally is to:
- increase the likelihood that members of the lineage will exhibit a particular favorable trait.
- increase the chances that favorable mutations may occur at some point in the lineage.
- produce offspring that will generate a lineage that is exceptionally vigorous and fertile.
- increase heterozygosity and variation in the lineage to increase the incidence of favorable traits.
Answer to question 21
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0004) Inbreeding increases
the homozygosity of the offspring in an inbred line. Variation in the population is reduced, and recessive
traits that are favorable (or unfavorable) are more likely to appear. The breeder can select those individuals
who have a combination of favorable traits and cull those animals that exhibit unfavorable traits. Reduced
heterozygosity generally means that many individuals will be less vigorous than in a population with
more variability, but the necessity to cull these animals is often outweighed by the increased incidence
of a particularly favorable trait such as higher milk production.
Correct Response: A. (Objective 0004) Inbreeding increases the homozygosity of
the offspring in an inbred line. Variation in the population is reduced, and recessive traits that are
favorable (or unfavorable) are more likely to appear. The breeder can select those individuals who have
a combination of favorable traits and cull those animals that exhibit unfavorable traits. Reduced heterozygosity
generally means that many individuals will be less vigorous than in a population with more variability,
but the necessity to cull these animals is often outweighed by the increased incidence of a particularly
favorable trait such as higher milk production.
Question 22
22. Which of the following breeds of dairy cattle are small, typically light fawn in color (although
they may range to black), and yield milk with the highest butterfat content of the major breeds raised
in the United States?
- Holstein
- Ayrshire
- Guernsey
- Jersey
Answer to question 22
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0005) Of the six major breeds
of dairy cattle raised in the United States, the Jersey is the smallest and generally yields the lowest
amount of milk. However they are excellent grazers and efficient utilizers of feed and their milk has
the highest concentration of butterfat (up to 5.4 percent) of all major breeds.
Correct Response: D. (Objective 0005) Of the six major breeds of dairy cattle raised
in the United States, the Jersey is the smallest and generally yields the lowest amount of milk. However
they are excellent grazers and efficient utilizers of feed and their milk has the highest concentration
of butterfat (up to 5.4 percent) of all major breeds.
Question 23
23. Which of the following best explains why there are considered to be ten essential amino acids for
swine, but no essential amino acids for ruminants such as dairy cattle?
- Ruminants need fewer types of amino acids to construct the proteins that are necessary for metabolism
and growth.
- Cellulose contains all essential amino acids, and ruminants can digest cellulose while swine and other
nonruminants cannot.
- Bacteria in the guts of ruminants can synthesize all essential amino acids from incomplete proteins
or from nitrogen such as urea.
- Ruminants have longer and more complex large intestines, which allows them to extract types of amino
acids that are excreted in the feces of nonruminants.
Answer to question 23
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0005) Essential amino acids
are those which the animal cannot synthesize for itself within its own body. For nonruminant farm animals
these amino acids must be supplied in the feed. Some proteins (e.g., soybeans) are considered to be
"complete," since they contain most, or all, of the essential amino acids. Ruminants can synthesize
all amino acids within their own bodies from bacterial action during fermentation of feed. The addition
of urea, which contains nitrogen, a basic building block of amino acids, to the feed facilitates this
process.
Correct Response: C. (Objective 0005) Essential amino acids are those which the
animal cannot synthesize for itself within its own body. For nonruminant farm animals these amino acids
must be supplied in the feed. Some proteins (e.g., soybeans) are considered to be "complete," since
they contain most, or all, of the essential amino acids. Ruminants can synthesize all amino acids within
their own bodies from bacterial action during fermentation of feed. The addition of urea, which contains
nitrogen, a basic building block of amino acids, to the feed facilitates this process.
Question 24
24. For which of the following diseases of swine would the administration of antibiotics be part of
a program of control?
- anemia
- influenza
- lice
- swine dysentery
Answer to question 24
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0005) Swine dysentery is
the only one of the four conditions named above that is caused by a bacterium. Administering antibiotics
would only be effective against bacterial diseases and would not be effective against viral diseases,
or those caused by parasites or nutritional problems.
Correct Response: D. (Objective 0005) Swine dysentery is the only one of the four
conditions named above that is caused by a bacterium. Administering antibiotics would only be effective
against bacterial diseases and would not be effective against viral diseases, or those caused by parasites
or nutritional problems.
Question 25
25. One difference between silage produced from alfalfa and silage produced from corn is that silage
produced from alfalfa is:
- higher in protein content, while corn silage is higher in carbohydrates.
- fermented anaerobically, while corn silage is exposed to air and not fermented.
- more palatable to dairy cows, while corn silage is less palatable to dairy cows.
- made from dried alfalfa hay, while corn silage is produced from freshly harvested green plants.
Answer to question 25
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0005) Since alfalfa is a
legume, while corn is not, alfalfa silage is higher in protein content than corn silage, and corn silage
is higher in carbohydrate content. Silage is a commonly used animal feed in Minnesota, especially during
the winter. It is produced from a variety of plants, such as alfalfa, corn, and various grasses. The
entire green plant is used, not just the grain. Silage is a moist feed and is produced from plants containing
50% to 60% water. Thus, using a crop for silage, rather than hay, is advantageous when summer weather
is not dry enough to produce hay. The plant material is chopped and packed as tightly as possible in
a silo or pit to exclude air. Fermentation through the action of anaerobic bacteria ensues, which converts
sugars to various acids and preserves the crop.
Correct Response: A. (Objective 0005) Since alfalfa is a legume, while corn is
not, alfalfa silage is higher in protein content than corn silage, and corn silage is higher in carbohydrate
content. Silage is a commonly used animal feed in Minnesota, especially during the winter. It is produced
from a variety of plants, such as alfalfa, corn, and various grasses. The entire green plant is used,
not just the grain. Silage is a moist feed and is produced from plants containing 50% to 60% water.
Thus, using a crop for silage, rather than hay, is advantageous when summer weather is not dry enough
to produce hay. The plant material is chopped and packed as tightly as possible in a silo or pit to
exclude air. Fermentation through the action of anaerobic bacteria ensues, which converts sugars to
various acids and preserves the crop.
Question 26
26. Johne's disease is a contagious, chronic, and sometimes lethal infection of the small intestine
of ruminants. It causes diarrhea, wasting, decreased milk production, and soft swelling under the jaw,
known as "bottle jaw." Many infected animals are asymptomatic, but once an animal begins to show symptoms,
death usually results. This disease is caused by:
- a single-cell protist related to the amoeba.
- a virus in the genus Shigella that may cause human Crohn's disease.
- a multicellular parasite in the hookworm family.
- a mycobacterium related to the one that causes human tuberculosis.
Answer to question 26
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0005) Johne's disease is
also known as Paratuberculosis and is a serious problem on Minnesota dairy farms. It is caused by the
bacterium Mycobacterium avium subspecies paratuberculosis. It is not easily controlled,
since many cases are asymptomatic or may take a long time to develop. The disease usually infects calves
that ingest infected manure, so strict sanitary procedures are the best way to control its spread. In
addition, testing of the herd for antibodies can identify infected animals, and it is strongly recommended
to test cows before purchasing and bringing them into an existing herd. Animals that test positive for
Johne's disease must be reported to the Minnesota Board of Animal Health.
Correct Response: D. (Objective 0005) Johne's disease is also known as Paratuberculosis
and is a serious problem on Minnesota dairy farms. It is caused by the bacterium Mycobacterium avium
subspecies paratuberculosis. It is not easily controlled, since many cases are asymptomatic
or may take a long time to develop. The disease usually infects calves that ingest infected manure,
so strict sanitary procedures are the best way to control its spread. In addition, testing of the herd
for antibodies can identify infected animals, and it is strongly recommended to test cows before purchasing
and bringing them into an existing herd. Animals that test positive for Johne's disease must be reported
to the Minnesota Board of Animal Health.
Question 27
27. Composting animal waste produces which of the following effects?
- breaking down complex carbon compounds into elemental carbon so that it can be more easily absorbed
by plants
- raising the percent of nitrogen in the compost by reducing the carbon to nitrogen ratio in the finished
compost
- reducing nitrogen that can burn plants by breaking down nitrogen compounds and releasing nitrogen gas
into the air
- increasing the amount of nitrogen in the compost by encouraging the growth of bacteria that fix nitrogen
from the air
Answer to question 27
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0006) During composting,
bacteria and other microorganisms break down organic material. These organisms use nitrogen to build
their bodies, but when they die, the nitrogen is recycled and not lost. However, bacteria and other
organisms use oxygen for metabolic respiration and release carbon dioxide as a waste product. The carbon
in the carbon dioxide therefore is removed from the compost, and the ratio of carbon to nitrogen present
in the compost is reduced.
Correct Response: B. (Objective 0006) During composting, bacteria and other microorganisms
break down organic material. These organisms use nitrogen to build their bodies, but when they die,
the nitrogen is recycled and not lost. However, bacteria and other organisms use oxygen for metabolic
respiration and release carbon dioxide as a waste product. The carbon in the carbon dioxide therefore
is removed from the compost, and the ratio of carbon to nitrogen present in the compost is reduced.
Question 28
28. Which of the following is likely to be the most significant advantage of using a deep litter system
in a chicken coop for raising cage-free laying hens?
- The litter facilitates social interactions among the chickens by providing hiding places for less dominant
birds as well as preferred areas that more dominant birds will claim.
- The litter serves as an efficient waste disposal system because it composts and breaks down wastes
with little smell and can be maintained over an extended period of time.
- The litter results in fewer cracked or broken eggs, since the laying hens deposit their eggs on the
soft material of the decomposing litter.
- The litter serves as a breeding ground for various insects that can supplement the chicken's regular
feed with a source of free, high-quality protein.
Answer to question 28
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0006) Deep litter systems
involve placing a layer of organic materials such as pine shavings over a dirt floor. As the hens deposit
wastes into the material new material is added on top. Eventually the litter can be several feet thick
with animal wastes mixed in with litter material. The system serves as a compost heap that breaks down
both litter and wastes with little odor. The litter can be removed as needed, and can often remain for
a year before it is removed and used as compost on gardens or fields.
Correct Response: B. (Objective 0006) Deep litter systems involve placing a layer
of organic materials such as pine shavings over a dirt floor. As the hens deposit wastes into the material
new material is added on top. Eventually the litter can be several feet thick with animal wastes mixed
in with litter material. The system serves as a compost heap that breaks down both litter and wastes
with little odor. The litter can be removed as needed, and can often remain for a year before it is
removed and used as compost on gardens or fields.
Question 29
29. One disadvantage of using anaerobic lagoons rather than aerobic lagoons to treat animal wastes is
that anaerobic lagoons:
- are more likely to allow wastes to percolate into groundwater.
- are more expensive to install, operate, and maintain.
- must be pumped out and the manure disposed of more frequently.
- produce strong, undesirable odors as a by-product of anaerobic digestion.
Answer to question 29
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0006) In anaerobic lagoons,
bacteria digest the animal wastes in the absence of oxygen, while in aerobic lagoons different types
of bacteria use oxygen in breaking down the wastes. By-products of anaerobic bacterial digestion include
toxic gases (e.g., methane, ammonia, hydrogen sulfide) that can cause strong odors and air pollution.
On the other hand, methane from anaerobic lagoons can be collected and used as a source of energy for
heating barns or other purposes.
Correct Response: D. (Objective 0006) In anaerobic lagoons, bacteria digest the
animal wastes in the absence of oxygen, while in aerobic lagoons different types of bacteria use oxygen
in breaking down the wastes. By-products of anaerobic bacterial digestion include toxic gases (e.g.,
methane, ammonia, hydrogen sulfide) that can cause strong odors and air pollution. On the other hand,
methane from anaerobic lagoons can be collected and used as a source of energy for heating barns or
other purposes.
Question 30
30. It would be most important to provide supplemental heating for which of the following newborn animals?
- foals
- piglets
- calves
- lambs
Answer to question 30
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0006) Newborn piglets have
almost no energy reserves at birth and may die quickly if they get chilled. One study showed that the
chances of a newborn pig dying in the first hours of life were seven times greater when the ambient
temperature was 15°C than when it was 25°C. Commonly, heated floors or radiant heaters are used
in farrowing houses, and a heated creep area is provided for the piglets for when they are a few days
old and can leave their mother. This allows the piglets to remain in a warmed space, while preventing
overheating of the sow.
Correct Response: B. (Objective 0006) Newborn piglets have almost no energy reserves
at birth and may die quickly if they get chilled. One study showed that the chances of a newborn pig
dying in the first hours of life were seven times greater when the ambient temperature was 15°C
than when it was 25°C. Commonly, heated floors or radiant heaters are used in farrowing houses,
and a heated creep area is provided for the piglets for when they are a few days old and can leave their
mother. This allows the piglets to remain in a warmed space, while preventing overheating of the sow.
Question 31
31. Compared with animal manures from small farms that are deposited directly on crop fields, sludge
and top water from anaerobic lagoons used in concentrated animal feeding operations (CAFOs) are considerably
lower in which of the following nutrients?
- calcium
- phosphorus
- potassium
- nitrogen
Answer to question 31
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0006) Top water from anaerobic
lagoons is regularly pumped out and sprayed on fields, while the sludge layer at the bottom of the lagoon
is cleaned out at regular intervals and applied to cropland. (Although a layer of sludge must be left
behind to prevent seepage from the lagoon into groundwater). Sludge is especially high in phosphorus,
but both sludge and top water are relatively poor sources of nitrogen because most of the nitrogen in
the manure is converted to ammonia and lost to the atmosphere during digestion by anaerobic bacteria.
Correct Response: D. (Objective 0006) Top water from anaerobic lagoons is regularly
pumped out and sprayed on fields, while the sludge layer at the bottom of the lagoon is cleaned out
at regular intervals and applied to cropland. (Although a layer of sludge must be left behind to prevent
seepage from the lagoon into groundwater). Sludge is especially high in phosphorus, but both sludge
and top water are relatively poor sources of nitrogen because most of the nitrogen in the manure is
converted to ammonia and lost to the atmosphere during digestion by anaerobic bacteria.
Question 32
32. Cattle egrets are often found near herds of grazing cattle. The egrets forage for small insects
that are stirred up by the cattle as they graze. The relationship between the egrets and the cattle
is best described by the ecological concept of:
- commensalism.
- parasitism.
- competition.
- mutualism.
Answer to question 32
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0007) Commensalism is defined
as a relationship between two species of animals where one species benefits, while the other species
neither benefits nor is harmed. In this case, the egrets benefit from the actions of the cattle, while
the cattle are unaffected by the behavior of the egrets.
Correct Response: A. (Objective 0007) Commensalism is defined as a relationship
between two species of animals where one species benefits, while the other species neither benefits
nor is harmed. In this case, the egrets benefit from the actions of the cattle, while the cattle are
unaffected by the behavior of the egrets.
Question 33
33. Which of the following is generally the most important element in a program of conservation and
management for preventing plant and wildlife loss and reduction of species diversity?
- removal of invasive species before they have spread
- preventing illegal collection of protected species
- preventing habitat loss and restoring degraded habitat
- controlling insect pests of plants and diseases of animals
Answer to question 33
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0007) By far, the primary
cause of loss of species diversity and reduction in the numbers of individuals in many species is the
loss of habitat. Agricultural activities, logging, residential and commercial building, and pollution
all contribute to the loss of habitat in Minnesota. Preservation of remaining habitat and restoration
of degraded habitat are the most important elements of any program of plant and wildlife conservation
and management.
Correct Response: C. (Objective 0007) By far, the primary cause of loss of species
diversity and reduction in the numbers of individuals in many species is the loss of habitat. Agricultural
activities, logging, residential and commercial building, and pollution all contribute to the loss of
habitat in Minnesota. Preservation of remaining habitat and restoration of degraded habitat are the
most important elements of any program of plant and wildlife conservation and management.
Question 34
34. Farmers in many states have earned extra income by selling the rights to produce renewable energy
on portions of their land. Selling the rights to build which of the following commercial renewable energy
facilities would likely be most feasible for Minnesota farmers?
- geothermal energy fields
- solar power arrays
- low-head hydroelectric dams
- wind power farms
Answer to question 34
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0007) Minnesota can and does
make use of all of the forms of renewable energy listed above. However, the northern location, topography,
and abundant wind resources of the state make it most suitable for large- and small-scale wind power
farms. Windmills also can be set up on farmland with less disruption of crop producing activities than
many other forms of renewable energy production facilities. Wind farms currently generate about 12 percent
of the power generated in the state and expansion is planned.
Correct Response: D. (Objective 0007) Minnesota can and does make use of all of
the forms of renewable energy listed above. However, the northern location, topography, and abundant
wind resources of the state make it most suitable for large- and small-scale wind power farms. Windmills
also can be set up on farmland with less disruption of crop producing activities than many other forms
of renewable energy production facilities. Wind farms currently generate about 12 percent of the power
generated in the state and expansion is planned.
Question 35
35. Sustainable farming methods require that the producer:
- make use of renewable rather than nonrenewable resources to the greatest extent possible.
- be willing to accept a much lower return on investment compared to that using nonsustainable methods.
- refrain from using nonorganic methods of pest and weed control, chemical fertilizers, and GMO crops.
- apply high-tech methods such as remote sensing to continuously monitor the condition of the crop.
Answer to question 35
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0007) Sustainable farmers
seek to lower their carbon footprint, especially by the use of renewable (wind, solar) rather than nonrenewable
(natural gas, oil) energy sources. Sustainable farming has been defined as a set of production practices
that form an integrated, site-specific system of farming that will last over the long term. The phrase
"over the long term" is critical for sustainable farming. Of the five necessities for crop production
(air, water, soil, sun, nutrients), controlling the use of water, soil, and nutrients is most important
for sustainable farming. Conserving water (e.g., recycling water, growing crops appropriate for rainfall
in a region, mulching), maintaining soil integrity (e.g., low-till plowing, avoiding compaction, incorporating
organic matter through cover cropping, preventing erosion), and using renewable sources of nutrients
where possible (e.g., incorporating legumes in crop rotations incorporating legumes, recycling animal
manures and crop residues, composting) all contribute to maintaining the long-term productivity of farmland.
Correct Response: A. (Objective 0007) Sustainable farmers seek to lower their carbon
footprint, especially by the use of renewable (wind, solar) rather than nonrenewable (natural gas, oil)
energy sources. Sustainable farming has been defined as a set of production practices that form an integrated,
site-specific system of farming that will last over the long term. The phrase "over the long term" is
critical for sustainable farming. Of the five necessities for crop production (air, water, soil, sun,
nutrients), controlling the use of water, soil, and nutrients is most important for sustainable farming.
Conserving water (e.g., recycling water, growing crops appropriate for rainfall in a region, mulching),
maintaining soil integrity (e.g., low-till plowing, avoiding compaction, incorporating organic matter
through cover cropping, preventing erosion), and using renewable sources of nutrients where possible
(e.g., incorporating legumes in crop rotations incorporating legumes, recycling animal manures and crop
residues, composting) all contribute to maintaining the long-term productivity of farmland.
Question 36
36. Which of the following best explains why sandy soils in Minnesota warm up more quickly in the spring
than soils with a higher proportion of silt or clay?
- Humus absorbs heat, preventing it from being reradiated out of the soil, and sandy soils contain more
humus than silt or clay soils.
- Sandy soils contain more air than silt or clay soils, which insulates the mineral particles from heat
loss.
- Water takes five times the energy to warm compared to mineral particles, and sandy soils contain less
water than silt or clay soils.
- Sandy soils have a lower albedo and reflect less sunlight than do silt and clay soils.
Answer to question 36
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0008) Sandy soils contain
a higher proportion of large-grain particles than silt or clay soils. As a result, sandy soils have
more air spaces and channels through which water can drain. Thus, sandy soils dry out more quickly in
the spring than silt or clay soils, which have a higher water content. Since it takes considerably more
energy to heat water than to heat rock particles, sandy soils, with their low water content, will warm
up more quickly in the spring. As a result, sandy soils can be worked (e.g., plowed, harrowed, planted)
earlier in the spring than silt or clay soils.
Correct Response: C. (Objective 0008) Sandy soils contain a higher proportion of
large-grain particles than silt or clay soils. As a result, sandy soils have more air spaces and channels
through which water can drain. Thus, sandy soils dry out more quickly in the spring than silt or clay
soils, which have a higher water content. Since it takes considerably more energy to heat water than
to heat rock particles, sandy soils, with their low water content, will warm up more quickly in the
spring. As a result, sandy soils can be worked (e.g., plowed, harrowed, planted) earlier in the spring
than silt or clay soils.
Question 37
37. Which of the following best describes how the structure of a soil affects its permeability?
- Ped size determines how much water is held in micropores inside each ped and how many large continuous
pore spaces are available for drainage.
- The roots of plants provide channels for water to flow through the soil, so fields that are covered
with a crop will be better drained than those that are bare.
- Organic matter soaks up and holds moisture, so the amount of organic matter determines how well or
poorly drained a particular soil will be.
- Particle size (e.g., sand, silt, clay) determines the total surface area of all particles in the soil,
which influences the amount of water held by surface tension.
Answer to question 37
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0008) Soil structure refers
to the way soil particles clump together into larger aggregates called peds. Soils with large peds tend
to be well drained since they provide large, continuous pore spaces between peds. At the same time,
they hold water in the small micropores within each ped. Massive soils are an example of a structureless
soil where aggregates have been broken down and particles stick to one another in a solid mass. Such
soils have very poor drainage.
Correct Response: A. (Objective 0008) Soil structure refers to the way soil particles
clump together into larger aggregates called peds. Soils with large peds tend to be well drained since
they provide large, continuous pore spaces between peds. At the same time, they hold water in the small
micropores within each ped. Massive soils are an example of a structureless soil where aggregates have
been broken down and particles stick to one another in a solid mass. Such soils have very poor drainage.
Question 38
38. Which of the following is likely to be the most practical and effective way for a grower to modify
the effects of texture of the soil in a field to improve its tilth?
- adding large amounts of sand to fine-textured soils and clay or silt to sandy soils
- plowing the soil more frequently and removing crop residues soon after harvest
- incorporating and mixing organic matter into the soil by plowing under cover crops
- adding large amounts of chemical fertilizers to the soil to speed crop root development
Answer to question 38
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0008) Soil texture refers
to the distribution of particle size (e.g., sand, silt, clay) in the soil and is difficult for a grower
to modify. The addition of organic matter by plowing under a cover crop is one of the most effective
ways of modifying the effects of texture on soil tilth. Organic matter improves the water and nutrient
holding capacity of sandy soils and creates larger pore spaces that improve permeability in clay soils.
Correct Response: C. (Objective 0008) Soil texture refers to the distribution of
particle size (e.g., sand, silt, clay) in the soil and is difficult for a grower to modify. The addition
of organic matter by plowing under a cover crop is one of the most effective ways of modifying the effects
of texture on soil tilth. Organic matter improves the water and nutrient holding capacity of sandy soils
and creates larger pore spaces that improve permeability in clay soils.
Question 39
39. The most likely reason for a grower to switch from conventional tillage to a no-till or minimum-tillage
method of soil preparation would be to help:
- control pests of the crop by leaving colonies of beneficial insects such as predators or parasites
of the main pest insects.
- provide weed control in the spring by leaving the crop residues to acts as a mulch against the development
of weeds.
- warm the soil more quickly in the spring by providing more surface area in the form of crop residues
to catch and hold sunlight.
- control soil erosion by leaving crop residues on the ground to break the force of rainwater and bind
soil particles together.
Answer to question 39
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0008) No-till and minimum-till
methods of postharvest field preparation have become more popular recently as it has been demonstrated
that leaving crop residues on the surface can help provide erosion control. The decaying roots of the
plants help hold soil particles together and provide organic matter to the soil, while the above-ground
portions of the crop residue break up raindrops that would otherwise disturb soil structure and lead
to erosion. On heavy clay soils, these methods of tillage also help prevent soil compaction by minimizing
the impact of heavy farm machinery on the soil.
Correct Response: D. (Objective 0008) No-till and minimum-till methods of postharvest
field preparation have become more popular recently as it has been demonstrated that leaving crop residues
on the surface can help provide erosion control. The decaying roots of the plants help hold soil particles
together and provide organic matter to the soil, while the above-ground portions of the crop residue
break up raindrops that would otherwise disturb soil structure and lead to erosion. On heavy clay soils,
these methods of tillage also help prevent soil compaction by minimizing the impact of heavy farm machinery
on the soil.
Question 40
40. Over many years, irrigation of cropland is associated with:
- depletion of nutrients from the soil.
- reduction in the soil's water retention capacity.
- buildup of hardpan beneath the soil's surface.
- increased salinization of the soil.
Answer to question 40
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0008) All irrigation water
contains dissolved salts derived from passage over the land. Even rainwater contains some salts. Although
salt concentrations in the water itself may be low, evaporation and use of water by plants and subsequent
transpiration leave salts behind. In areas that have been heavily irrigated for a number of years, these
salts may even form a whitish crust on the ground. Saline soils decrease the ability of plants to take
up water from the soil. This lowers crop yields and, in some cases, results in soil that cannot support
a crop. Salinization is particularly important in arid areas where heavy rainfall does not flush salts
from the soil, but may be found anywhere excessive irrigation has been used.
Correct Response: D. (Objective 0008) All irrigation water contains dissolved salts
derived from passage over the land. Even rainwater contains some salts. Although salt concentrations
in the water itself may be low, evaporation and use of water by plants and subsequent transpiration
leave salts behind. In areas that have been heavily irrigated for a number of years, these salts may
even form a whitish crust on the ground. Saline soils decrease the ability of plants to take up water
from the soil. This lowers crop yields and, in some cases, results in soil that cannot support a crop.
Salinization is particularly important in arid areas where heavy rainfall does not flush salts from
the soil, but may be found anywhere excessive irrigation has been used.