1.
Water is a simple chemical compound, each molecule composed
of one oxygen and two ____________ atoms. Why, then, is it so important?
Most fundamentally, water is essential for life.
Every living organism on earth must have water in some form in order to
survive. Every living cell is composed primarily of water. When space
probes are dispatched to other planets in search of other life forms,
they look for the presence to water to determine if life, as we know
it, is possible there.
Correct Answer
D. Hydrogen
Explanation
Water is composed of one oxygen and two hydrogen atoms. It is essential for life as every living organism requires water to survive. Water makes up a significant portion of living cells. When scientists search for other life forms on other planets, they look for the presence of water as it is a key indicator of the possibility of life as we know it.
2.
What properties or characteristics of water make it so essential?
Special Properties
Water is a special chemical substance. In chemical terms, the
water molecule is strongly dipolar. This property makes water an effective ____________,
particulary for crystalline salts. The small size of hydrogen atoms
makes it possible for molecules of water to effectively bond together
or chemically associate, particularly at lower temperatures. However,
water also partially dissociates into very minute concentrations of
acid [H3O+] and base [OH-] ions, a characteristic which leads to the use of the pH scale to measure relative acidity or alkalinity.
Correct Answer
B. Solvent
Explanation
Water is a special chemical substance due to its strong dipolar nature. This property makes it an effective solvent, especially for crystalline salts. The small size of hydrogen atoms allows water molecules to bond together or chemically associate, especially at lower temperatures. Additionally, water can partially dissociate into small concentrations of acid and base ions, which is why the pH scale is used to measure acidity or alkalinity.
3.
The chemistry of water leads to some very
interesting, and important, physical properties. At the temperatures
and pressures found on the surface of this planet, water can be found
in all three physical states: solid, liquid and ____________.
While pure water freezes at 0 degrees Celsius, because of molecular
association its maximum density is reached at 4 degrees C. This permits
solid water (ice) to float on liquid water. This molecular association
also accounts for the strong surface tension exhibited by liquid water,
which permits certain animals to move about on its surface and aids
water to penetrate tiny spaces in the soil and elsewhere. In its liquid
form, water has relatively high viscosity, thereby slowing its rate of
runoff from the land and keeping it more available for terrestrial life.
Correct Answer
C. Gaseous
Explanation
Water can exist in all three physical states: solid, liquid, and gaseous. The given information states that at the temperatures and pressures found on the surface of this planet, water can be found in all three physical states. It also mentions that water freezes at 0 degrees Celsius and its maximum density is reached at 4 degrees Celsius. This information indicates that at temperatures above 4 degrees Celsius, water is in its liquid state, and at temperatures below 0 degrees Celsius, it is in its solid state (ice). Therefore, the missing state must be gaseous, as water vapor is the gaseous form of water.
4.
Water has a much higher boiling point than its
nearest chemical relatives, making it relatively efficient in the high
temperature conversion of heat into work. Greater heat is required to
vaporize water than that needed to vaporize an equal weight of any
other liquid. This makes water vapour a good carrier of energy
and is responsible for its dominant effects in modifying the
____________ of the earth. Indeed, more heat is required to raise the
temperature of water than is required to raise the temperature of an
equivalent weight of any other liquid. This means that water, even in
its liquid state, can transport great quantities of heat and have major
effects on climate.
Correct Answer
B. Climates
Explanation
Water's high boiling point compared to other liquids allows it to efficiently convert heat into work at high temperatures. It requires more heat to vaporize water than any other liquid, making water vapor an effective carrier of energy. This characteristic of water is responsible for its dominant effects in modifying climates on Earth. Additionally, water has a high specific heat capacity, meaning it requires more heat to raise its temperature compared to other liquids. This allows water, even in its liquid state, to transport large amounts of heat and have significant impacts on climate.
5.
Pure water is transparent to the visible
wavelengths of light, with maximum transmission of light in the blue
portion of the visible spectrum. It also transmits reasonably well many
of the wavelengths used by plants for ____________, thereby supporting
plant growth in oceans and other water bodies. Water vapour in the
atmosphere, unlike liquid water, absorbs the sun's ultraviolet
radiation which otherwise would be extremely harmful to life on earth.
Both liquid water and water vapour are nontransparent to the infrared
radiation which is given off by the earth, thereby preventing much of
this heat from being lost to space and keeping earth's temperatures at
habitable levels.
Correct Answer
C. pHotosynthesis
Explanation
Pure water transmits the wavelengths used by plants for photosynthesis. This means that plants can receive the necessary light energy for photosynthesis to occur, promoting their growth in oceans and other water bodies. Water vapor in the atmosphere absorbs harmful ultraviolet radiation from the sun, protecting life on Earth. Additionally, both liquid water and water vapor are nontransparent to infrared radiation, preventing the loss of heat to space and maintaining habitable temperatures on Earth.
6.
While oxygen atoms comprise almost 80% of water by
weight, this oxygen is chemically bound and not available to plants and
animals. However, some molecules of oxygen do dissolve in water,
particularly at lower temperatures. This dissolved oxygen is available
for ____________ and permits animals to inhabit lakes, streams and
oceans.
Correct Answer
D. Respiration
Explanation
Oxygen dissolved in water is available for respiration, which is the process of taking in oxygen and releasing carbon dioxide, typically done by animals. This dissolved oxygen is essential for aquatic organisms to survive and thrive in lakes, streams, and oceans.
7.
These special properties of water would be interesting, but not nearly as important, were not water so abundant
here on earth. With an estimated 1.4 billion cubic kilometres of water
on this planet, its special properties become extremely important. Not
all water, however, is readily available. The oceans, which cover well
over two-thirds of the earth's surface, also contain about 97% of all
its water. However, there are also substantial quantities of fresh
water in various forms and locations. Almost 90% of this fresh water is
locked up in polar ice-caps and glaciers. Only about 0.3% of all water
on earth is currently available fresh water, and almost all of this is
located in natural underground reservoirs or ____________. Less than 1
of every 5,000 litres of water on earth can be found as either surface
or atmospheric fresh water. However, this minute fraction still
represents an estimated total volume of more than 200,000 cubic
kilometres, enough to cover all of Canada to a depth of 17 metres.
How, then, is all this water so essential? Why, with so much
water around, do we have so many problems finding it and using it?
Correct Answer
B. Aquifiers
Explanation
The passage mentions that almost all of the currently available fresh water on Earth is located in natural underground reservoirs or aquifers. This suggests that aquifers are an important source of fresh water. The passage also states that only a small fraction of water on Earth is available as surface or atmospheric fresh water, indicating that pools, puddles, and bubbles are not significant sources of fresh water. Therefore, the correct answer is aquifers.
8.
As we noted earlier, water readily dissolves most
salts. However, water is a poor solvent for proteins and other large
organic molecules in living cells. This means that liquid water can
transport nutrient elements to and within living cells without
dissolving and destroying the organic molecules of which cells are
made. Water also transports waste elements away from cells. Thus, all living cells contain water,
with the proportion ranging from 3-5% in resting seeds to perhaps 95%
in very young plant tissues and jellyfish. This water penetrates the
cell protoplasm, but does not dissolve it. Increased water content
leads to increased chemical or ____________ activity within the cell.
Without water, there would be no life.
This means that the distribution of life on earth is highly
dependent on the distribution of water. Our needs, both metabolically
and otherwise, are often affected by the distribution of water and by
competition for available water.
Correct Answer
A. Metabolic
Explanation
Increased water content leads to increased metabolic activity within the cell. This is because water plays a crucial role in various metabolic processes, such as the transportation of nutrients and waste elements. Without water, these processes would not be able to occur, and therefore, there would be no life. The distribution of life on earth is highly dependent on the distribution of water, as water availability affects the metabolic needs of organisms and their competition for resources.
9.
Of course, water is not evenly distributed,
and this has a major impact on us, both as living organisms and as a
complex social species. Most water is concentrated in the oceans. Even
on land, the distribution of water varies greatly because of weather
patterns, evaporation rates, and other factors.
We humans often choose to live in areas with dry, sunny
climates. At the same time, we require large quantities of water for
domestic, recreational, agricultural, and industrial uses. This
inevitably leads to water ____________ problems and water
redistribution schemes are undertaken. In other situations, human
populations settle on fertile coastal plains or in river valleys. These
areas are susceptible to flooding during storms and spring run-off.
Again, issues of water management become important.
In either case, engineering solutions are usually available to
alter water distribution, although often at high cost. We must attempt
to weigh fairly the costs and benefits, both short- and long-term,
before undertaking such engineering projects.
Correct Answer
B. Shortage
Explanation
The passage discusses the uneven distribution of water and the impact it has on humans. It mentions that humans often choose to live in areas with dry climates but still require large quantities of water for various purposes. This inevitably leads to water shortage problems, which require water redistribution schemes. Therefore, the correct answer is "shortage" as it aligns with the context of the passage.
10.
Direct support of life, while most important, is only one of a multitude of roles played by water on our planet.
As noted earlier, water is extremely important as a modifier of climate.
It stores heat in great quantities, transports it around the globe,
both in ocean currents and in atmospheric vapour, and helps to retain
stored ____________ at the earth's surface by reducing its radiative
loss to space.
Correct Answer
B. Heat
Explanation
Water plays a crucial role in regulating the Earth's climate by storing and transporting heat. It has a high heat capacity, which means it can absorb and store large amounts of heat energy. This stored heat is then distributed around the globe through ocean currents and atmospheric vapor, influencing weather patterns and climate. Additionally, water helps to retain heat at the Earth's surface by reducing its radiative loss to space. Therefore, the correct answer is "heat."
11.
As an effective solvent, and as a physical mass releasing energy as it moves downhill, water is a major modifier of the earth's surface.
It erodes and breaks down rock, carries materials downstream, and
deposits these eroded mineral particles in depressions where they can
combine with organic materials to form ____________. It can also erode
these soils, leaving a greatly altered landscape. The very nature of
our planet's surface is a product of water and its distribution.
Of course, the very ability of water to run downhill and shape
the earth's surface is dependent on a process known as the water cycle or hydrologic cycle.
Correct Answer
C. Soils
Explanation
Water erodes and breaks down rock, carrying the eroded mineral particles downstream. These particles are then deposited in depressions, where they can combine with organic materials to form soils. Water also has the ability to erode these soils, shaping the earth's surface. Therefore, the correct answer is "soils".
12.
In this cycle, heat energy from the sun causes liquid water and
ice to evaporate or sublimate and escape to the atmosphere as vapour.
This vapour is then transported within the atmosphere until such time
as changing conditions cause some of it to precipitate or fall back to
the earth's surface as rain, snow, or dew. This water, once returned to
the surface, can resume its downhill movement until it reaches the
oceans or is vaporized once more. This process of ____________ is
extremely important as a means of cleansing water of its dissolved
substances, which are left behind when the water evaporates.
Correct Answer
B. Vaporization
Explanation
The process described in the passage involves the evaporation of water from the surface, its transportation in the atmosphere, and then its precipitation back to the earth's surface. This continuous cycle of evaporation and condensation is known as the water cycle. Vaporization is the correct answer because it refers to the process of liquid water changing into water vapor through evaporation or sublimation, which is an essential part of the water cycle.
13.
As human civilizations have developed, many additional uses of water
have become important. Some of these uses have resulted in problems
both for ourselves and for the earth as a whole. Our challenge it to
use water in sustainable ways, such that its use by future generations
of humans and other living organisms is not compromised.
With its abundance and its properties as a solvent, water has long been used for cleaning and for dissolving waste
products. We wash in it; we wash our possessions and products with it;
we use it to dissolve our unwanted materials and flush them away.
Unfortunately, when we have completed our cleaning and waste removal
activities, the resulting water is dirty or "polluted". When we
return water to nature in this state, we are relying on natural
processes to cleanse it. We are also passing our __________ on to other
users or to other living organisms. These wastes may be toxic to these
other living things. The more concentrated these wastes become, the
more toxic we can expect them to be. Water treatment facilities must be
used to remove these wastes before the water is returned to nature. We
must then find ways to safely dispose of, or reuse, these so-called
"waste" materials, such that they do not cause adverse ecosystem
effects now or in the future.
Correct Answer
B. Wastes
Explanation
The passage discusses the problem of water pollution caused by the waste materials that are dissolved in water during cleaning activities. These waste materials, referred to as "wastes" in the passage, can be toxic to other living organisms when the polluted water is returned to nature. The passage emphasizes the need for water treatment facilities to remove these wastes before returning the water to nature and the importance of finding safe ways to dispose of or reuse these waste materials to prevent adverse effects on ecosystems. Therefore, the correct answer is "wastes."
14.
Humans rely on water to sustain their agricultural crops.
Usually, the natural precipitation will be sufficient to water these
crops. In other situations, artificial watering systems, usually
referred to as irrigation, are used. These irrigation schemes involve
modification of the natural water distribution patterns. Sometimes,
extra water is drawn from natural groundwater reservoirs far below the
soil surface. Other times, rivers are dammed and their waters are
diverted through canals to be used on agricultural fields. In the short
term, these irrigated croplands can be highly productive. However, any
of these diversion schemes have potential long-term consequences for
the ecosystems being altered. Often, we have failed to anticipate these
problems. Over time, irrigated lands may become saturated with salts
from this water, resulting in serious loss of __________. The runoff
water from agricultural fields may be contaminated by fertilizers or
pesticides used to grow and protect the crops. These contaminants may
harm downstream ecosystems in a variety of ways.
Correct Answer
A. Fertility
Explanation
Over time, irrigated lands may become saturated with salts from the water used for irrigation. This can lead to a serious loss of fertility in the soil. The excess salts can accumulate in the soil and hinder the growth and development of crops. This can result in reduced agricultural productivity and the need for additional measures to restore fertility to the soil. Therefore, the potential long-term consequence of these irrigation schemes is the loss of fertility in the irrigated croplands.
15.
Water running downhill is an important source of __________. By
damming rivers and streams, we have harnessed some of this energy to
generate electricity, power machinery, and provide light and heat for
our homes and businesses. Done properly, this energy generation should
have little polluting effect on the water being used.
Correct Answer
B. Energy
Explanation
Water running downhill is an important source of energy. This energy can be harnessed by damming rivers and streams to generate electricity, power machinery, and provide light and heat for our homes and businesses. When done properly, this energy generation should not have a significant polluting effect on the water being used.
16.
Dams may also be
beneficial to some users by retaining water longer, minimizing extremes
of flow, and reducing downstream flooding. However, changing the flow
patterns in rivers by damming can have adverse effects on ____________
and wildlife which rely on those rivers for their life support. It can
also affect the downstream uses of those rivers by other people, and
reduce the fertility and productivity of downstream ecosystems which
rely on flooding for nutrient input. Creating new reservoirs can flood
large areas and may, under certain conditions, lead to pollution of the
water. The long term consequences of all these possible effects should
be considered when making decisions about the use of water for energy
generation.
Correct Answer
B. Fish
Explanation
The given passage states that changing the flow patterns in rivers by damming can have adverse effects on wildlife which rely on those rivers for their life support. Fish are a type of wildlife that heavily rely on rivers for their habitat and survival. Therefore, the adverse effects mentioned in the passage would directly impact fish populations. The passage also mentions that reducing downstream flooding caused by dams can affect the fertility and productivity of downstream ecosystems, which again includes fish populations. Hence, the correct answer is fish.
17.
Water is also used industrially and domestically for transferring heat during various cooling or heating
processes. Again, if done properly, this should not result in
contamination of the water with pollutants. However, the very act of
changing the water temperature can have adverse effects on downstream
life when this water is discharged to nature. Care must be taken to
ensure that such effects are avoided, or at least minimized.
Water, in its liquid form, is a primary medium for heavy
____________. Giant ships ply the oceans and large lakes of the world,
carrying raw materials and manufactured products. In northwestern
Ontario, the waterways were the only practical means of travel for
native peoples and for the first Europeans who traded with them. These
uses of water should be sustainable, provided ships are careful to
avoid dumping waste materials, and provided accidents do not result in
the spillage of toxic pollutants such as oil. Unfortunately, both of
these problems continue to occur all too frequently.
Correct Answer
B. Transportation
Explanation
The passage discusses the various uses of water, including its use in transportation. It mentions that water is used for transporting raw materials and manufactured products through ships in oceans and lakes. It also states that these uses of water should be sustainable as long as waste materials are not dumped and accidents causing the spillage of toxic pollutants are avoided. Therefore, the correct answer is "transportation" because it aligns with the information provided in the passage.
18.
Water is so fundamental to our very existence that we must seek to
learn how it affects our lives, and how our lives affect it and the
other living things that rely on water for their existence. One way to
do this is to study the role of water in ecosystems, particularly in aquatic ecosystems where water is so abundant.
In northwestern Ontario, lake ecosystems are everywhere. A
better understanding of these systems can give us a better appreciation
of the importance of water and the roles it plays in linking us to the
world around us. The diagram, below, presents a simplified view of a
typical lake ____________.Energy from the sun drives this ecosystem, but all the communities
shown, the plants on shore, and those humans who use this ecosystem,
are linked by the common element, water. Anything affecting the quality
or availability of this water will have an impact on the entire
ecosystem. However, ecosystems are complex and our understanding of
them is incomplete. Often, We are not able to predict in advance
exactly what that effect might be.
Correct Answer
B. Ecosystem
Explanation
The passage discusses the importance of water in ecosystems and how it affects our lives and the other living things that rely on it. It specifically mentions studying the role of water in aquatic ecosystems, such as lake ecosystems in northwestern Ontario. The diagram presented in the passage represents a simplified view of a typical lake ecosystem. It states that all the communities, plants, and humans in this ecosystem are linked by water, and any changes in the quality or availability of water can have an impact on the entire ecosystem. Therefore, the correct answer is "ecosystem".
19.
Water is an ____________ human need. It is also an invaluable resource
to human societies; for cleaning and waste removal, for energy
generation, for food production, for cooling and heating, for
transportation, and for recreation.
Correct Answer
B. Essential
Explanation
Water is described as an "invaluable resource" that serves various purposes in human societies, such as cleaning, waste removal, energy generation, food production, cooling and heating, transportation, and recreation. This highlights the importance and necessity of water in fulfilling these essential needs and activities. Therefore, the correct answer is "essential."
20.
Wise use of water, with a view to the
long-term needs of other users, both human and otherwise, can be
____________. We must continue to study the role of water in our lives
and learn more about the functioning of our ecosystems. Only with
better knowledge and understanding can we make wise decisions for water use and management.
Correct Answer
C. Sustainable
Explanation
The word "sustainable" is the correct answer because it aligns with the idea of using water in a way that meets the long-term needs of all users, including humans and other organisms. It suggests that we should use water in a manner that can be maintained or continued without causing harm to the environment or depleting water resources. By studying the role of water and understanding how ecosystems function, we can make informed decisions about water use and management that are sustainable in the long run.