Sleep

Why do we sleep? It can be dangerous to lose awareness of the external world. If nothing
else, sleep might seem to take away from time that could be spent on productive, or even
necessary, activities. But people cannot override indefinitely the desire to sleep; the body
shuts down whether we like it or not. There are three general explanations that describe the
adaptiveness of sleep: restoration, circadian cycles, and facilitation of learning.

The restoration theory of sleep emphasizes that the brain and body need to rest and that
sleep allows the body to repair itself. Indeed, growth hormone is released during deep
sleep, and one of its functions if to facilitate repair of damaged tissue. Additional evidence
that sleep is a time of restoration is that people who have engaged in vigorous physical
activity, such as running marathons, seem to sleep longer. But people sleep even if they
spend the day being physically inactive. In addition, it appears that sleep allows the brain to
strengthen the body’s ability to fight disease.

Numerous laboratory studies have examined the effects of sleep deprivation on physical
and cognitive performance. Surprisingly, most studies find that two or three days of
deprivation have little effect on strength, athletic ability, or cognitive performance on
complex tasks. Performing boring or ordinary tasks when sleep deprived, however, is nearly
impossible. A brain-imaging study of sleep-deprived people found increased activation of
the prefrontal cortex, suggesting that some brain regions may compensate for the effects of
deprivation. Over long periods, however, sleep deprivation eventually causes problems with
mood and cognitive performance. Indeed, studies using rats have found that extended sleep
deprivation compromises the immune system and leads to death. Interestingly, sleep
deprivation might serve one very useful purpose, which is helping people overcome
depression. Consistent evidence has emerged over the past decade demonstrating that
depriving depressed people of sleep sometimes alleviates their depression. This effect
appears to occur because sleep deprivation leads to increased activation of serotonin
receptors, which combat depression.

The circadian rhythm theory of sleep proposes that sleep has evolved to keep animals
quiet and inactive during times of the day when there is greatest danger, which for most is
when it is dark. Physiological and brain processes are regulated into regular patterns known
as circadian rhythms (“circadian” roughly translates to “about a day”). Body temperature,
hormone levels, and sleep-wake cycles are all examples of circadian rhythms, which operate
like biological clocks.  These circadian rhythms are themselves controlled by cycles of light
and dark, although animals continue to show these rhythms when light cues are removed.

1
  According to the circadian rhythm theory, animals need only so much time in the day to
accomplish the necessities of survival, and it is adaptive to spend the remainder of the time
inactive, preferably hidden away.  Accordingly, the amount an animal sleeps depends on
how much time it needs to obtain food, how easily it can hide, and how vulnerable it is to
attack. Small animals sleep a great deal, whereas large animals vulnerable to attack, such as
cows and deer, sleep little.  Large animals that are not vulnerable, such as lions, also sleep
a great deal.

It has been proposed that sleep may be important because it is involved in the
strengthening of nerve cell connections that serve as the basis of learning. The general idea
is that circuits that have been wired together during the waking period are consolidated, or
strengthened, during sleep. Robert Stickgold and colleagues conducted a study in which they
required participants to learn a complex visual-discrimination task. They found that
participants improved at the task only if they had slept for at least six hours following
training. Periods of sleep with increased brain activity as well as periods of sleep with
reduced brain activity appeared to be important for learning to take place. The researchers
argued that learning the task required nerve cell changes that normally occur only during
sleep. Although learning certainly can take place in the absence of sleep, sleep seems to be
an efficient time for the consolidation of learning. Infants and the very young, who learn an
incredible amount in a few short years, sleep the most and also spend the most time in
periods of sleep with higher brain activity.

1. The word “indefinitely” in the passage is closest in meaning to

A) easily
B) without effects
C) on purpose
D) endlessly

2. According to paragraph 2, all of the following are considered to be evidence that sleep is
needed for the body to repair itself EXCEPT:
A) The body’s resistance to disease is strengthened through sleep.
B) Body tissues are restored by the release of hormones during sleep.
C) The longer people sleep, the more activity occurs.
D) Sleep occurs whether or not physical activity has taken place.

3. Why does the author say “Performing boring or ordinary tasks when sleep deprived,
however, is nearly impossible”?

2
 A) To identify a type of task in which being sleep-deprived for a few days actually does
affect physical and cognitive performance
B) To suggest that simple tasks are easier to perform than complex tasks after sleep
deprivation
C) To indicate an important finding of a brain-imaging study on the effects of sleep
deprivation on the prefrontal cortex
D To suggest that physical acts are preformed more easily than cognitive acts after sleep
deprivation

4. The phrase “compensate for” in the passage is closest in meaning to

A) add to
B) make up for
C) slow down
D) repair

5. The word “extended” in the passage is closest in meaning to

A) measurable
B) forced
C) occasional
D) lengthened

6. The word “Consistent” in the passage is closest in meaning to

A) Critical
B) Convincing
C) Unvarying
D) Considerable

7. According to paragraph 3, what was one unexpected finding reported by studies

investigating sleep deprivation?
A) Sleep deprivation helps people perform better on complex tasks.
B) Sleep deprivation of a few days’ duration does not significantly weaken performance on
challenging tasks.
C) Sleep deprivation is more common in people who are physically inactive than it is in
active people.
D) Sleep deprivation can sometimes temporarily improve physical ability.

8. Which of the following can be inferred from the discussion about sleep deprivation in
paragraph 3?

3
 A) Short-term sleep deprivation has a negative impact on athletic performance.
B) Short-term sleep deprivation severely harms the immune system.
C) Sleep deprivation can have both positive and negative effects.
D) Sleep deprivation improves cognitive development by activating serotonin receptors.

9. According to paragraph 4, which of the following is NOT true of the circadian rhythms of
animals?
A) Circadian rhythms regulate physiological processes such as body temperature, hormone
levels, and sleep-wake cycles of animals.
B) Animals that are kept in darkness will stop following circadian rhythms.
C) The daily periods of light and dark regulate the circadian rhythms of animals.
D) Sleep occurs during the part of the circadian cycle in which an active animal would be in
the most danger.

10. According to the circadian rhythm theory described in paragraph 5, which of the
following does NOT determine the amount of time an animal sleeps?
A) How easily the animal can hide from attackers
B) How much energy the animal’s food provides
C) How likely it is that the animal will be attacked when it is active
D) The amount of time the animal needs to find food

11. According to paragraph 6, what was a major finding of the study conducted by Robert
Stickgold and his colleagues?
A) Most learning takes place during deep sleep.
B) Information and skills acquired during the day are reinforced during sleep.
C) Visual discrimination tasks cannot be learned without sleeping afterward.
D) At least six hours of sleep before performing a task is necessary for learning to occur.

12. In paragraph 6, why does the author mention that infants and very young people sleep
the most?
A) To argue against the findings of the study conducted by Robert Stickgold and his
colleagues
B) To suggest that learning is not possible if infants and young people are deprived of sleep
C) To support the claim that sleep is critical to learning and reinforces it in important ways
D) To indicate that the brain circuits responsible for learning are more active in infants and
young people than they are in adults

4
13. Look at the four squares [] that indicate where the following sentence could be added
to the passage.

But how do biological clocks affect the amount of time an animal sleeps each day?

Where would the sentence best fit?

14. Prose Summary

Several theories have been proposed to explain why sleep is important.

Answer Choices:
A) Sleep may be necessary to increase the body’s energy for use in physical activity, which
in turn may speed up the process of tissue restoration.
B) Sleep may help repair damage to the body, although evidence suggests that only a long-
term lack of sleep would cause a decline in physical health and cognitive functioning.
C) Sleep may control the development of daily rhythms that regulate basic physiological
properties, such as body temperatures and hormone levels.
D) The function of sleep cycles in animals may be to allow them to minimize activity during
periods of high risk.
E) Sleep may influence brain development by increasing the number of neuronal
connections, which would explain why infants demonstrate higher brain activity than
adults do.
F) Sleep may enable certain physiological changes that normally occur only during sleep to
support and strengthen the process of learning.

The Classic Mayan Collapse

5
 The Classic Mayan civilization, located in the lowlands of present-day southern Mexico and
Central America, began a precipitous decline around A.D. 900. The majority of the people
abandoned their great urban centers, buildings were no longer kept up, and carved
monuments – a hallmark of the civilization – were no longer created. Various theories about
this collapse have been explored, such as invasion from foreigners, natural disaster, disease,
failure of agricultural techniques, and internal revolt, although it is a combination of factors
that probably constitutes the ultimate explanation.

When one looks at the remains of a city, it is difficult to determine why a building
collapsed. Whether caused by natural disaster, natural decay, or structural weakness, the
rubble and remains can look very similar. There is no historical record of earthquakes in the
central Mayan lowland area at the end of the Classic period, although some evidence
suggests that Mayan centers in the southern lowlands experienced earthquakes. Hurricanes
can destroy significant quantities of crops and are therefore another possibility; however,
the effects of both hurricanes and earthquakes are generally local and not so widespread as
to cause the abandonment of the entire lowlands. An ill-timed natural disaster certainly
could have compounded other problems brewing in Mayan civilization.

The possibility of drought throughout the area has also been considered and to date
stands as likely contributor to the collapse. Lake Chichancanab, located in the central
Yucatan Peninsula, is the largest closed-basin lake in the Yucatan. Studies of lake-bottom
sediment revealed that between A.D. 800 and A.D. 1000, the lake experienced its driest
period in the past 8,000 years, with aridity peaking in A.D. 922. These are useful findings
indeed; however, Lake Chichancanab represents only one area in the Mayan region and
evidence for drought in other regions needs to be examined.

Agricultural collapse is most likely to have been another important factor.  Research
done in 1985 shows an accumulation of silt in the lakes of the Peten region at the end of the
tenth century.  An increase in sediment signifies an erosion of soil brought on by
deforestation.  Slash-and-burn agriculture – a style of farming that requires clearing new
plots of forest land every two years – was probably the Maya’s primary means of
subsistence.  It is a system of agriculture requiring large amounts of land and resulting in
deforestation. It is possible that the Maya simply tapped their natural resources until none
that were accessible were left.

As populations in the lowlands grew, additional methods of farming were developed, but
the number of people may have outweighed the capacity of the land, resulting in a food
shortage. Population studies of the Mayan area continue, but current general consensus

6
puts the numbers well into the millions. Some scientists say there was a conversion from
diverse agricultural management to the exclusive cultivation of maize, which concluded with
the end of the Classic period. The shift reflects the change in Mayan culture and in how the
people were managing their land, although it does not explain why the change came about.
Once the culture’s resources were stressed, people were more vulnerable to the hardships
of natural disaster, poor health, and social chaos.

In addition, pottery, architecture, and sculpture in some Mayan centers changed

significantly at the end of the Classic period, suggesting a takeover by an outside or
surrounding group. Clear evidence of this kind of invasion has been found at Altar de
Sacrificios and Seibal, although few other sites show such blatant signs. It is not understood
exactly where the invaders came from, but most likely they were from the surrounding
Mexican states. Also supporting this theory is the fact that the seafaring Putun Maya of
Tabasco, Mexico, were in power in the Yucatan peninsula by the post-classic period. Lowland
centers whose success depended on internal trade routes were no longer in the heart of the
economic and political action; as the Putun gained power, the focus of trade seems to have
moved toward the coasts. This could have pushed people to abandon their homeland,
following the center of commerce.

The Classic Mayan civilization, located in the lowlands of present-day southern Mexico and
Central America, began a precipitous decline around A.D. 900. The majority of the people
abandoned their great urban centers, buildings were no longer kept up, and carved
monuments – a hallmark of the civilization – were no longer created. Various theories about
this collapse have been explored, such as invasion from foreigners, natural disaster, disease,
failure of agricultural techniques, and internal revolt, although it is a combination of factors
that probably constitutes the ultimate explanation.
1. According to paragraph 1, which of the following indicated the collapse of Mayan
civilization around A.D. 900?
A) The Maya stopped carving stone monuments.
B) The Maya no longer explored foreign lands.
C) Most of the Maya moved to urban centers.
D) The Maya adopted foreign agricultural techniques.

When one looks at the remains of a city, it is difficult to determine why a building collapsed.
Whether caused by natural disaster, natural decay, or structural weakness, the rubble and
remains can look very similar. There is no historical record of earthquakes in the central
Mayan lowland area at the end of the Classic period, although some evidence suggests that
Mayan centers in the southern lowlands experienced earthquakes. Hurricanes can destroy

7
significant quantities of crops and are therefore another possibility; however, the effects of
both hurricanes and earthquakes are generally local and not so widespread as to cause the
abandonment of the entire lowlands. An ill-timed natural disaster certainly could have
compounded other problems brewing in Mayan civilization.
2. What point does the author want to make in paragraph 2 about earthquakes?
A) Earthquakes were the most likely cause for the collapse of Classic Mayan civilization.
B) It cannot be determined from examination of the remains of Mayan buildings whether
or not they were destroyed by earthquakes.
C) The historical records of earthquakes in Mayan lowlands are not accurate.
D) Many different earthquakes contributed to the abandonment of the entire Mayan
lowlands.

3. According to paragraph 2, why is it unlikely that a natural disaster was the only cause of
the collapse of Mayan civilization?
A) There were no earthquakes or hurricanes at the end of the Classic period.
B) Buildings collapsed as a result of natural decay and structural weaknesses.
C) Natural disasters did not occur often enough to cause lasting damage to Mayan crops.
D) The effects of natural disasters tend to be limited to areas smaller than the area of the
Mayan collapse.

The possibility of drought throughout the area has also been considered and to date stands
as likely contributor to the collapse. Lake Chichancanab, located in the central Yucatan
Peninsula, is the largest closed-basin lake in the Yucatan. Studies of lake-bottom sediment
revealed that between A.D. 800 and A.D. 1000, the lake experienced its driest period in the
past 8,000 years, with aridity peaking in A.D. 922. These are useful findings indeed; however,
Lake Chichancanab represents only one area in the Mayan region and evidence for drought
in other regions needs to be examined.
4. According to paragraph 3, what evidence is there that a drought contributed to the
collapse of Mayan civilization between A.D. 800 and A.D. 1000?
A) The Maya constructed a large closed-basin lake in the Yucatan.
B) There are indications of drought throughout Mayan territory.
C) Studies of sediment taken from Lake Chichancanab show that there were very dry
periods.
D) Drought is thought to have affected several other civilizations.

5. The word “compounded” in the passage is closest in meaning to

A) outweighed
B) created

8
 C) raised awareness to
D) added to

6. The word “accessible” in the passage is closest in meaning to

A) desirable
B) available
C) useful
D) renewable

Agricultural collapse is most likely to have been another important factor.  Research done
in 1985 shows an accumulation of silt in the lakes of the Peten region at the end of the tenth
century.  An increase in sediment signifies an erosion of soil brought on by deforestation.
 Slash-and-burn agriculture – a style of farming that requires clearing new plots of forest
land every two years – was probably the Maya’s primary means of subsistence.  It is a
system of agriculture requiring large amounts of land and resulting in deforestation. It is
possible that the Maya simply tapped their natural resources until none that were accessible
were left.
7. According to paragraph 4, what may have caused the collapse of Mayan agriculture?
A) Mayan farming practices eventually made land unusable for agriculture.
B) Mayan farmers were unable to find crops suited to the soil of the available land.
C) Sediment from the lakes of the Peten region began to erode the soil on which Mayan
agriculture depended.
D) The Maya developed other means of subsistence that made agriculture less important.

8. The word “consensus” in the passage is closest in meaning to

A) knowledge
B) estimation
C) analysis
D) widespread agreement

9. The word “exclusive” in the passage is closest in meaning to

A) late
B) main
C) sole
D) intensive

As populations in the lowlands grew, additional methods of farming were developed, but the

9
number of people may have outweighed the capacity of the land, resulting in a food
shortage. Population studies of the Mayan area continue, but current general consensus
puts the numbers well into the millions. Some scientists say there was a conversion from
diverse agricultural management to the exclusive cultivation of maize, which concluded with
the end of the Classic period. The shift reflects the change in Mayan culture and in how the
people were managing their land, although it does not explain why the change came about.
Once the culture’s resources were stressed, people were more vulnerable to the hardships
of natural disaster, poor health, and social chaos.

10. In paragraph 5, why does the author provide information about Mayan population
figures?
A) To explain the effect of natural disaster on the Mayan population
B) To support the claim that resources may have been scarce
C) To indicate that overpopulation resulted in social chaos
D) To illustrate the gradual decline in urban population

In addition, pottery, architecture, and sculpture in some Mayan centers changed significantly
at the end of the Classic period, suggesting a takeover by an outside or surrounding group.
Clear evidence of this kind of invasion has been found at Altar de Sacrificios and Seibal,
although few other sites show such blatant signs. It is not understood exactly where the
invaders came from, but most likely they were from the surrounding Mexican states. Also
supporting this theory is the fact that the seafaring Putun Maya of Tabasco, Mexico, were in
power in the Yucatan peninsula by the post-classic period. Lowland centers whose success
depended on internal trade routes were no longer in the heart of the economic and political
action; as the Putun gained power, the focus of trade seems to have moved toward the
coasts. This could have pushed people to abandon their homeland, following the center of
commerce.

11. Which of the sentences below best expresses the essential information in the highlighted
sentence in the passage? Incorrect choices change the meaning in important ways or
leave out essential information.
A) Successful trade depended more on gaining power along the coasts than on the existing
internal routes of the lowlands.
B) As the Putun gained power, the coasts replaced the lowland centers as the heart of
economic and political activity.
C) Trade between lowland centers and the coasts seems to have been a result of the
economic and political action of the Putun.
D) The Putun probably gained power initially through the economic and political success of

10
 lowland trade centers.

12. Which of the following can be inferred from paragraph 6 about the Maya by the post-
classic period?
A) They had stopped creating pottery, architecture, and sculpture.
B) They had replaced agriculture with seafaring as a means of survival.
C) They depended on the Putun-controlled centers of commerce.
D) They were moving to the coasts with a view to expanding their territory.

13. Look at the four squares [] that indicate where the following sentence could be added
to the passage.

Some geological evidence suggests that the Maya were using up all their agricultural
land.

Where would the sentence best fit?

14. Prose Summary

Researchers have offered a variety of theories to explain the decline of the Mayan
civilization around A.D. 900.

Answer Choices:
A) Evidence taken from remains of city buildings has led to the theory that an earthquake
or a hurricane caused the Mayan collapse.
B) Although evidence is incomplete, it is believed that natural disasters and drought played
a role in the collapse of Mayan civilization.
C) Studies show that Lake Chichancanab, a huge closed-basin lake that once existed in the
Yucatan, dried up during a drought around A.D. 922.
D) Research suggests that environmentally destructive agricultural practices and poor
planning probably left the Maya without a sufficient, sustainable food supply.
E) By the end of the Classic period, internal economic power struggles and invasions from
other groups seem to have decreased the power of previously influential lowland
centers.
F) The shift from a diverse agriculture to maize suggests the influence of invaders on the
cultural practices of the Maya.

The Qualities of a Good Trout Stream

11
 There are a number of streams in the United States in which trout (a species of fish)
flourish. Such streams as the Gunnison River, the Battenskill River, Silver Creek, and
numerous others throughout the country are famed for the abundance of trout that live in
them. Yet look at the range of geographical locations in which these streams occur: from
deciduous eastern forests to coniferous forests to sagebrush steppe-desert regions.
Obviously, they must have something in common if all support robust populations of these
fish. What are the common conditions that produce a productive and viable trout habitat?

Trout streams are generally cool- to cold-water streams, and most trout species prefer
cold water. Brown trout, however, generally tolerate warmer temperatures than other trout
do, and they can be found at lower elevations or in warmer stream sections. Preferred
temperatures range from 10C to 16C. As water temperatures approach about 21C, trout are
less able to compete with other fish species for food and other resources. Lethal
temperatures for trout range from 23C to 26C, depending on the species. Each life stage and
function (e.g. swimming) has optimal temperatures, and these optima vary with species.

Cover is also vital to trout survival, so good trout streams contain an adequate amount
and diversity of cover to provide shelter from predators and strong currents. This cover can
be quite diverse and includes vegetation, boulders in the streambed, overhanging banks,
logs, root wads, undercut areas in the bank of the stream, and even shade from overhanging
objects. Trout are territorial; that is, each trout tends to remain in a relatively small area of
the stream, however, the area of a stream that a trout prefers varies with both its age and
species. Thus, adequate cover that provides suitable trout habitats must be present

12
throughout the stream or river, not just here and there.

One of the most important and characteristic features of good trout stream is the
alternation of riffles (shallow areas where the surface is somewhat turbulent) with pools of
slow, smooth-flowing water. This configuration is especially well developed in gravel-bed
streams and allows trout the luxury of having both productive riffle areas in which to feed
and deeper pools in which to rest and take cover. Trout have been found to hold a “station”
behind a rock or other obstruction in a rapidly flowing section of the stream. This permits
the fish to expend little energy in the calm area behind the obstruction while waiting to
make a foray into the rapid flow to capture drifting prey.

Trout frequently capture dislodged insects floating downstream in the water column or on
the surface of the water. They will also actively pick insects from the stream bottom. Thus, a
good trout stream must support an abundant population of insects, crustaceans, and other
aquatic invertebrates sufficient to feed a large trout population. Terrestrial insects become
food items when they are blown into the stream, and, of course, larger trout feed
extensively on small fishes – minnows, small trout, or other species.

Successful, reproducing trout populations require streams or rivers that provide suitable
spawning areas for the fishes to construct their nests (redds) and lay their eggs.  Good
spawning sites are gravel-bottom areas that are largely free of silt so that the water will flow
around the eggs once they are buried by the fishes.  This water must also be high in
dissolved oxygen in order to adequately aerate the developing eggs.  Thus spawning areas
are usually in cooler reaches because cold water holds more dissolved oxygen. 

Typically trout habitat is composed of a combination of large rocks, rubble, and smaller
amounts of sand and gravel. This does not mean that successful trout populations are never
found in streams with predominantly sand and silt bottoms. However, trout inhabiting such
areas must have access to stream sections with gravel bottoms to construct their redds and
lay their eggs. The typical rocky substratum provides many factors that are conducive to
successful trout populations. These include cover from predators, resting places from the
current, abundant niches for invertebrate food items, and the enhanced aeration that results
from water tumbling over and among the rocks.

There are a number of streams in the United States in which trout (a species of fish) flourish.

13
Such streams as the Gunnison River, the Battenskill River, Silver Creek, and numerous others
throughout the country are famed for the abundance of trout that live in them. Yet look at
the range of geographical locations in which these streams occur: from deciduous eastern
forests to coniferous forests to sagebrush steppe-desert regions. Obviously, they must have
something in common if all support robust populations of these fish. What are the common
conditions that produce a productive and viable trout habitat?
1. The word “robust” in the passage is closest in meaning to
A) similar
B) evidence
C) natural
D) healthy

2. In paragraph 1, why does the author mention the differing environments of three trout
streams in the United States?
A) To indicate that the features of good trout streams have been studied in various
geographical regions
B) To challenge the idea that most rivers in the United States are unsuitable for trout
C) To identify the three streams with the most abundant trout populations
D) To make the reader wonder what makes a good stream

Trout streams are generally cool- to cold-water streams, and most trout species prefer cold
water. Brown trout, however, generally tolerate warmer temperatures than other trout do,
and they can be found at lower elevations or in warmer stream sections. Preferred
temperatures range from 10C to 16C. As water temperatures approach about 21C, trout are
less able to compete with other fish species for food and other resources. Lethal
temperatures for trout range from 23C to 26C, depending on the species. Each life stage and
function (e.g. swimming) has optimal temperatures, and these optima vary with species.
3. The word “optimal” in the passage is closest in meaning to
A) exact
B) ideal
C) different
D) special

4. Paragraph 2 suggests which of the following about water temperatures of trout streams?
A) Trout are able to tolerate higher water temperatures than most other types of fish.
B) Most species of trout prefer water temperatures between 16C and 21C.
C) No species of trout is able to survive in water temperatures higher than 26C.
D) Brown trout generally prefer the water temperature of streams at high elevations.

14
Cover is also vital to trout survival, so good trout streams contain an adequate amount and
diversity of cover to provide shelter from predators and strong currents. This cover can be
quite diverse and includes vegetation, boulders in the streambed, overhanging banks, logs,
root wads, undercut areas in the bank of the stream, and even shade from overhanging
objects. Trout are territorial; that is, each trout tends to remain in a relatively small area of
the stream, however, the area of a stream that a trout prefers varies with both its age and
species. Thus, adequate cover that provides suitable trout habitats must be present
throughout the stream or river, not just here and there.
5. According to paragraph 3, good trout streams are characterized by which of the following?
A) Areas throughout the stream where trout can gather.
B) Lots of vegetation, which provides good for the trout.
C) Plenty of routes, so that the trout can escape from predators.
D) A variety of objects in and above the stream that can hide an protect the trout.

One of the most important and characteristic features of good trout stream is the
alternation of riffles (shallow areas where the surface is somewhat turbulent) with pools of
slow, smooth-flowing water. This configuration is especially well developed in gravel-bed
streams and allows trout the luxury of having both productive riffle areas in which to feed
and deeper pools in which to rest and take cover. Trout have been found to hold a “station”
behind a rock or other obstruction in a rapidly flowing section of the stream. This permits
the fish to expend little energy in the calm area behind the obstruction while waiting to
make a foray into the rapid flow to capture drifting prey.
6. The word “obstruction” in the passage is closest in meaning to
A) natural formation
B) small object
C) protection
D) barrier

7. According to paragraph 4, why does a trout hold a station behind a rock?

A) To wait for drifting prey without having to fight against the force of the current
B) To more easily capture prey that becomes trapped behind the rocks
C) To remain hidden from potential prey that drift into the calm area of the stream
D) To signal to neighboring trout that all prey drifting through a particular area have been
claimed

Trout frequently capture dislodged insects floating downstream in the water column or on

15
the surface of the water. They will also actively pick insects from the stream bottom. Thus, a
good trout stream must support an abundant population of insects, crustaceans, and other
aquatic invertebrates sufficient to feed a large trout population. Terrestrial insects become
food items when they are blown into the stream, and, of course, larger trout feed
extensively on small fishes – minnows, small trout, or other species.
8. According to paragraph 5, all of the following are often sources of food for trout EXCEPT
A) insects that are being moved down the stream by its currents
B) insects that live primarily on land rather than in the water
C) the eggs of small fishes such as minnows and small trout
D) insects found along the stream bottom

Successful, reproducing trout populations require streams or rivers that provide

suitable spawning areas for the fishes to construct their nests (redds) and lay their eggs. 
Good spawning sites are gravel-bottom areas that are largely free of silt so that the water
will flow around the eggs once they are buried by the fishes.  This water must also be high
in dissolved oxygen in order to adequately aerate the developing eggs.  Thus spawning
areas are usually in cooler reaches because cold water holds more dissolved oxygen. 
9. According to paragraph 6, the presence of silt affects trout spawning areas by
A) forcing eggs out of their nests and into flowing water
B) decreasing the amount of water flowing around eggs
C) providing material for trout to use in building their nests
D) making it difficult for predators to locate eggs

Typically trout habitat is composed of a combination of large rocks, rubble, and smaller
amounts of sand and gravel. This does not mean that successful trout populations are never
found in streams with predominantly sand and silt bottoms. However, trout inhabiting such
areas must have access to stream sections with gravel bottoms to construct their redds and
lay their eggs. The typical rocky substratum provides many factors that are conducive to
successful trout populations. These include cover from predators, resting places from the
current, abundant niches for invertebrate food items, and the enhanced aeration that results
from water tumbling over and among the rocks.
10. The word “predominantly” in the passage is closest in meaning to
A) exclusively
B) mainly
C) frequently
D) equally

11. According to paragraph 7, streams with sand and silt on their bottoms

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 A) contain reproducing trout only if the stream has an area with a gravel bottom
B) cannot support significant trout populations
C) provide abundant material for trout to construct their redds
D) provide good conditions for the formation of the rocky substratum

12. According to paragraph7, rocky river bottoms benefit trout in all of the following ways
EXCEPT:
A) They provide trout with gravel that trout can transport to their redds in sandy areas.
B) They provide still locations where trout are protected from the current.
C) They provide many areas in which the trout’s prey can be found.
D) They allow trout to hide from their predators.

13. Look at the four squares [] that indicate where the following sentence could be added
to the passage.

But clear, flowing water alone does not ensure the healthy development of fish eggs.

Where would the sentence best fit?

14. Prose Summary

Streams must possess a particular set of features in order to support trout populations.

Answer Choices:
A) Trout are the most common type of fish in the United States because they can live in so
many different kinds of rivers.
B) Overhanging banks and branches, logs, and root wads provide the necessary food for
trout by dropping insects into the stream.
C) Trout generally require cold water for survival, but different species and ages of trout
prefer somewhat different water temperatures.
D) Riffles and strong currents enable trout to find food more easily, while pools and rocks
provide important resting places for trout.
E) Trout typically live in streams with sand and silt bottoms because these areas are high in
dissolved oxygen.
F) Trout require streams with areas of gravel in which to construct their redds and bury
their eggs.

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