Chapter 2

Question 1

Sperm whales dive to great depths, spending more than an hour underwater before returning to
the surface to breathe. During their extended dives, where do they store oxygen to maintain their
metabolic processes?
A) in the lungs (as a gas)
B) in the blood (bound to hemoglobin) and in the muscles (bound to myoglobin)
C) in the brain (bound to neurons) and in the heart (bound to the pericardium)
D) in extracellular fluids (as dissolved oxygen)

Answer 1

B) in the blood (bound to hemoglobin) and in the muscles (bound to myoglobin)

Question 2

Diving birds living in very cold regions (like the Adélie penguin described in the text) rely on
what kind of insulation against the extreme cold of their surroundings?
A) a layer of fat beneath their skin
B) a layer of specialized proteins beneath their skin
C) air trapped in their plumage
D) water trapped in their plumage

Answer 2

C) air trapped in their plumage

Question 3

Water has an unusual property relevant to its significance as the basis of life as we know it.
Which property is it?
A) Water has an immense capacity to dissolve inorganic compounds, facilitating the chemical
processes of living systems.
B) The high density of water achieves the concentrations of molecules necessary for rapid
chemical reactions.
C) No other common substance is liquid under most conditions at the earth’s surface.
D) all of the above

Answer 3

D) all of the above

Question 4

Which of the following properties of water is most important in preventing the bottoms of large
bodies of water (lakes and oceans) from freezing solid?
A) Water conducts heat rapidly.
B) Water is most dense at 4°C.
C) Water is capable of dissolving a wide array of substances.
D) Freezing of water requires the removal of 80 times as much heat as that needed to lower the
temperature of the same quantity of water by 1°C.

Answer 4

B) Water is most dense at 4°C.

Question 5

The bodies of many plants and animals are denser than the water in which they live. Which of
the following attributes helps prevent these organisms from sinking?
A) gas-filled swim bladder (some fish)
B) filamentous appendages (some tiny marine animals)
C) accumulation of fats and oils (many aquatic organisms)
D) all of the above

Answer 5

D) all of the above

Question 6

Of the nutrients listed below, all except one are required by all organisms. Which is it? (Hint:
This element is required by diatoms.)
A) nitrogen B) phosphorus C) potassium D) sulfur E) silicon

Answer 6

E) silicon

Question 7

The element molybdenum is required in relatively large amounts by which of the following
organisms?
A) nitrogen-fixing bacteria B) all bacteria C) all plants D) all animals

Answer 7

A) nitrogen-fixing bacteria

Question 8

With the exception of oxygen, carbon, and some nitrogen, plants acquire their essential elements
in what form?
A) as elements occurring in atmospheric gases
B) as elements occurring in minerals in soils and rocks
C) as elements occurring in ions dissolved in water
D) all of the above

Answer 8

C) as elements occurring in ions dissolved in water

Question 9

By the time rivers deliver water to the oceans, that water is enriched in many dissolved
substances. Given that water droplets that condense from water vapor in the atmosphere are
essentially pure water, what is the source of these dissolved substances?
A) atmospheric gases
B) minerals acquired from particles of dust and droplets of ocean spray in the atmosphere
C) minerals acquired from rocks and soils
D) all of the above

Answer 9

D) all of the above

Question 10

The oceans of the earth have been receiving substances dissolved in water for much of the
earth’s history, resulting in the present levels of dissolved salts (about 3.4% by weight). Of the
two important oceanic solutes listed below, one reached its current level eons ago, while the
other is still gradually increasing today. Which is still increasing today?
A) calcium carbonate (CaCO3) B) sodium chloride (NaCl)

Answer 10

B) sodium chloride (NaCl)

Question 11

How would you characterize the acidity/alkalinity of most naturally occurring surface waters?
A) highly acidic
B) moderately acidic
C) approximately neutral
D) moderately alkaline
E) highly alkaline

Answer 11

C) approximately neutral

Question 12

Phosphorus often limits plant production in terrestrial environments. Why is this the case?
A) Phosphorus forms volatile compounds that are rapidly lost to the atmosphere.
B) Phosphorus binds with heavy metals (arsenic, cadmium, and mercury), forming compounds
toxic to plants.
C) Phosphorus, even when abundant, forms compounds in the soil that do not dissolve easily in
water.
D) Phosphorus typically exists as phosphate ions (PO4
3-), which are not biologically active.

Answer 12

C) Phosphorus, even when abundant, forms compounds in the soil that do not dissolve easily in
water.

Question 13

Of the following size classes of soil mineral particles, which are the smallest, thus having the
greatest surface area per unit volume of soil?
A) clay
B) silt
C) sand
Chapter 2: Adaptations to the Physical Environment: Water and Nutrients
6
D) All of the above are equivalent in size and surface area per unit volume.

Answer 13

A) clay

Question 14

Water molecules tend to adhere to the surfaces of soil particles. This physical force determines
the matric potential of the soil, which in turn contributes to the water potential of the soil. As a
soil dries out, the remaining water molecules are bound more __________ to the soil mineral
particles, resulting in an increasingly __________ soil matric potential.
A) loosely, positive
B) loosely, negative
C) tightly, positive
D) tightly, negative

Answer 14

D) tightly, negative

Question 15

Equal volumes of dry mineral soil are placed in two containers. The containers are designed to
retain the soils they contain, but both have bottoms that are freely permeable to water. One soil is
clayey and the other is sandy. Water is applied to the top of each container until it drains freely
from the bottom of the container. No additional water is added, and each container is allowed to
stand until no water drains from the bottom. Which container retains more water?
A) The container with the clayey soil.
B) The container with the sandy soil.
C) Both will contain the same amount of water.
D) Neither will contain any water.

Answer 15

A) The container with the clayey soil.

Question 16

Which of the following soil matric potentials is considered by agronomists to represent the
wilting point?
A) –0.01 MPa
B) –0.1 MPa
C) –1.5 MPa
D) –10 MPa

Answer 16

C) –1.5 MPa

Question 17

Of the following size classes of soil mineral particles, which contribute the most to waterholding
capacity of a soil?
A) clay
B) silt
C) sand
D) All of the above are equivalent in contribution to water-holding capacity

Answer 17

A) clay

Question 18

When a membrane permeable to water separates water of more negative potential on one side of
the membrane from water of less negative potential on the other, what will be the tendency of the
water molecules?
A) There will be a net diffusion of water molecules across the membrane from the side of more
negative potential to the side of less negative potential.
B) There will be a net diffusion of water molecules across the membrane from the side of less
negative potential to the side of more negative potential.
C) There will be equal movement of water molecules across the membrane in both directions.
D) There will be no movement of water molecules across the membrane.

Answer 18

B) There will be a net diffusion of water molecules across the membrane from the side of less
negative potential to the side of more negative potential.

Question 19

How do plants cause water to move from the soil into their roots?
A) They actively pump water molecules across the cell membranes of their root cells.
B) They excrete substances from their roots that “push” water molecules into their root cells.
C) They maintain low concentrations of solutes in their root cells.
D) They maintain high concentrations of solutes in their root cells.

Answer 19

D) They maintain high concentrations of solutes in their root cells.

Question 20

How do plants prevent the depletion of solutes from their root cells into the dilute aqueous
solution contained in the surrounding soil?
A) They actively pump solute molecules from the soil solution, across their cell membranes, and
into their root cells.
B) They have semipermeable membranes surrounding their root cells.
C) They maintain large molecules, such as soluble carbohydrates and proteins, in their root
cells.
D) all of the above

Answer 20

D) all of the above

Question 21

How do plants growing in deserts and salty environments obtain water from the soil?
A) by greatly expanding the surface area of their root systems
B) by actively pumping water molecules from the soil into their root cells
C) by increasing the concentrations of solutes in their root cells
D) by decreasing the concentrations of solutes in their root cells

Answer 21

C) by increasing the concentrations of solutes in their root cells

Question 22

According to the cohesion-tension theory of water movement in plants, what generates the force
needed to move water from the roots to the tops of the tallest trees?
A) pressure generated by molecular pumps located in the root cells
B) pressure generated by molecular pumps located in the xylem cells of the stem
C) the highly negative potential generated when water evaporates from leaf cells into the
atmosphere
D) none of the above

Answer 22

C) the highly negative potential generated when water evaporates from leaf cells into the
atmosphere

Question 23

Transpiration occurs when water evaporates from leaf cell surfaces into the air spaces within the
leaves, exiting the leaves through __________.
A) stomates
B) xylem elements
C) guard cells
D) surface hairs

Answer 23

A) stomates

Question 24

Mangroves grow on salt-laden coastal mudflats that are inundated daily by high tides. How do
these plants address problems of water acquisition and elimination of excess salts?
A) by maintaining high concentrations of organic solutes in their roots
B) by excluding salts from their roots by active transport
C) by actively excreting salt from glands located on the surfaces of their leaves
D) all of the above

Answer 24

D) all of the above

Question 25

Certain marine birds and reptiles have evolved specialized organs to assist in the elimination of
excess salts. What are these organs?
A) enlarged kidneys
B) modified tear glands
C) specialized cells in the stomach lining
D) specialized scales on their legs

Answer 25

B) modified tear glands

Question 26

Freshwater fish are hyperosmotic, living in a medium that has lower salt concentration than their
bodies. As a consequence, these animals have to contend with which of the following?
A) replacing water lost to the surrounding medium while eliminating excess salts
B) retaining salts while eliminating excess water absorbed from the surrounding medium

Answer 26

B) retaining salts while eliminating excess water absorbed from the surrounding medium

Question 27

Marine fish (excluding certain sharks and rays) are hypo-osmotic, living in a medium with a
higher salt concentration than their bodies. As a consequence, these animals have to contend with
which of the following?
A) replacing water lost to the surrounding medium while eliminating excess salts
B) retaining salts while eliminating excess water absorbed from the surrounding medium

Answer 27

A) replacing water lost to the surrounding medium while eliminating excess salts

Question 28

Which of the following kinds of fish would you expect to drink water?
A) freshwater fish
B) marine fish

Answer 28

B) marine fish

Question 29

Marine species of sharks and rays have a unique way of raising the osmotic potential of their
blood to that of the surrounding seawater. What is this mechanism?
A) retention of urea in the bloodstream
B) retention of sodium chloride in the bloodstream
C) retention of small carbohydrate molecules in their bloodstream
D) all of the above

Answer 29

A) retention of urea in the bloodstream

Question 30

What challenge do carnivorous terrestrial animals face with regard to their nitrogen economy?
A) They consume nitrogen (in the form of proteins and nucleic acids) in excess of their needs,
but cannot afford the large amount of water required to eliminate this nitrogen as ammonium
ions.
B) Because their diets are deficient in nitrogen, they must exert strict control over loss of
ammonium ions along with other waste products.

Answer 30

A) They consume nitrogen (in the form of proteins and nucleic acids) in excess of their needs,
but cannot afford the large amount of water required to eliminate this nitrogen as ammonium
ions.

Question 31

As water cools, its density increases until it reaches a temperature of __________, at which point
it becomes less dense upon further cooling.

Answer 31

4 degrees C

Question 32

The __________ of water resists the movement of a body through it but also slows the rate of
sinking.

Answer 32

viscosity

Question 33

The element __________ is a structural component of nucleic acids, phospholipids, and bone.

Answer 33

phosphorus

Question 34

The element __________ is a structural component of plant cell walls.

Answer 34

calcium

Question 35

Some solid compounds consist of electrically charged atoms or groups of atoms called
__________.

Answer 35

ions

Question 36

Acidity is commonly expressed as __________, which is the negative of the common logarithm
of hydrogen ion concentration, measured in moles per liter.

Answer 36

pH

Question 37

The amount of water that is held in a soil against the force of gravity by a matric potential of less
than –0.01 MPa is called the __________.

Answer 37

field capacity

Question 38

The force with which an aqueous solution attracts water by osmosis is known as its __________
potential.

Answer 38

osmotic

Question 39

Most aquatic animals produce a simple metabolic by-product of nitrogen metabolism called
__________.

Answer 39

ammonia

Question 40

Terrestrial animals face the dual challenges of excreting nitrogen while conserving water. Birds
and reptiles face these challenges by excreting excess nitrogen in the form of __________, which
can be passed as a highly concentrated paste.

Answer 40

uric acid