OpenStax Anatomy & Physiology 2e Student Answer Guide
This file is copyright 2022, Rice University. All Rights Reserved.
,OpenStax Anatomy & Physiology 2e Student Answer Guide
ANSWER KEY
Chapter 1
1 Fatty acid catabolism. 3 X-rays. 5 PET scans can indicate how patients are responding to chemotherapy. 6 C 8 A 10 D 12
C 14 C 16 C 18 C 20 D 22 D 24 D 26 C 28 An understanding of anatomy and physiology is essential for any career in
the health professions. It can also help you make choices that promote your health, respond appropriately to signs of illness, make
sense of health-related news, and help you in your roles as a parent, spouse, partner, friend, colleague, and caregiver. 30 Chemical,
cellular, tissue, organ, organ system, organism. 32 When you are sitting at a campfire, your sense of smell adapts to the smell of
smoke. Only if that smell were to suddenly and dramatically intensify would you be likely to notice and respond. In contrast,
the smell of even a trace of smoke would be new and highly unusual in your residence hall, and would be perceived as danger. 34
In a sealed bottle of sparkling water, carbon dioxide gas is kept dissolved in the water under a very high pressure. When you open
the bottle, the pressure of the gas above the liquid changes from artificially high to normal atmospheric pressure. The dissolved
carbon dioxide gas expands, and rises in bubbles to the surface. When a bottle of sparkling water is left open, it eventually goes
flat because its gases continue to move out of solution until the pressure in the water is approximately equal to atmospheric pressure.
36 The four components of a negative feedback loop are: stimulus, sensor, control center, and effector. If too great a quantity of the
chemical were excreted, sensors would activate a control center, which would in turn activate an effector. In this case, the effector
(the secreting cells) would be adjusted downward. 38 If the body were supine or prone, the MRI scanner would move from top to
bottom to produce frontal sections, which would divide the body into anterior and posterior portions, as in “cutting” a deck of cards.
Again, if the body were supine or prone, to produce sagittal sections, the scanner would move from left to right or from right to left
to divide the body lengthwise into left and right portions. 40 CT scanning subjects patients to much higher levels of radiation than
X-rays, and should not be performed repeatedly.
Chapter 2
1 The mass number is the total number of protons and neutrons in the nucleus of an atom. 3 The water hydrolyses, or breaks,
the glycosidic bond, forming two monosaccharides. 4 D 6 A 8 B 10 C 12 B 14 A 16 C 18 A 20 B 22 D 24 B 26 A 28
B 30 D 32 B 33 These four elements—oxygen, carbon, hydrogen, and nitrogen—together make up more than 95 percent of
the mass of the human body, and the body cannot make elements, so it is helpful to have them in consumables. 35 Magnesium’s
12 electrons are distributed as follows: two in the first shell, eight in the second shell, and two in its valence shell. According to the
octet rule, magnesium is unstable (reactive) because its valence shell has just two electrons. It is therefore likely to participate in
chemical reactions in which it donates two electrons. 37 Water is a polar molecule. It has a region of weakly positive charge and
a region of weakly negative charge. These regions are attracted to ions as well as to other polar molecules. Oils are nonpolar,
and are repelled by water. 39 It is not. An exchange reaction might be AB + CD → AC + BD or AB + CD → AD + BC
. In all chemical reactions, including exchange reactions, the components of the reactants are identical to the components of the
products. A component present among the reactants cannot disappear, nor can a component not present in the reactants suddenly
appear in the products. 41 Lemon juice is one hundred times more acidic than orange juice. This means that lemon juice has a one
hundred-fold greater concentration of hydrogen ions. 43 Maltose contains 12 atoms of carbon, but only 22 atoms of hydrogen and
11 atoms of oxygen, because a molecule of water is removed during its formation via dehydration synthesis.
Chapter 3
1 Higher temperatures speed up diffusion because molecules have more kinetic energy at higher temperatures. 3 an enzyme 5 the
spindle 6 B 8 C 10 B 12 A 14 A 16 C 18 A 20 C 22 C 24 B 26 B 28 C 30 Only materials that are relatively small and
nonpolar can easily diffuse through the lipid bilayer. Large particles cannot fit in between the individual phospholipids that are
packed together, and polar molecules are repelled by the hydrophobic/nonpolar lipids that line the inside of the bilayer. 32 These
four phenomena are similar in the sense that they describe the movement of substances down a particular type of gradient. Osmosis
and diffusion involve the movement of water and other substances down their concentration gradients, respectively. Filtration
describes the movement of particles down a pressure gradient, and the movement of ions away from like charge describes their
movement down their electrical gradient. 34 Peroxisomes and lysosomes are both cellular organelles bound by lipid bilayer
membranes, and they both contain many enzymes. However, peroxisomes contain enzymes that detoxify substances by transferring
hydrogen atoms and producing H2O2, whereas the enzymes in lysosomes function to break down and digest various unwanted
materials. 36 During cell division, one cell divides to produce two new cells. In order for all of the cells in your body to maintain
a full genome, each cell must replicate its DNA before it divides so that a full genome can be allotted to each of its offspring cells.
If DNA replication did not take place fully, or at all, the offspring cells would be missing some or all of the genome. This could be
disastrous if a cell was missing genes necessary for its function and health. 38 Transcription is really a “copy” process and
translation is really an “interpretation” process, because transcription involves copying the DNA message into a very similar RNA
message whereas translation involves converting the RNA message into the very different amino acid message. The two processes
also differ in their location: transcription occurs in the nucleus and translation in the cytoplasm. The mechanisms by
This file is copyright 2022, Rice University. All Rights Reserved.
, OpenStax Anatomy & Physiology 2e Student Answer Guide
which the two processes are performed are also completely different: transcription utilizes polymerase enzymes to build mRNA
whereas translation utilizes different kinds of RNA to build protein. 40 A cyclin is one of the primary classes of cell cycle control
molecules, while a cyclin-dependent kinase (is one of a group of molecules that work together with cyclins to determine progression
past cell checkpoints. By interacting with many additional molecules, these triggers push the cell cycle forward unless prevented
from doing so by “stop” signals, if for some reason the cell is not ready. 42 Embryonic stem cells derive from human embryos,
which are destroyed to obtain the cells. The destruction of human embryos is an ethical problem. And, the DNA in an embryonic
stem cell would differ from the DNA of the person being treated, which could result in immune problems or rejected of tissue.
Chapter 4
1 Most somatic stem cells give rise to only a few cell types. 3 Skeletal muscle cells are striated. 5 Approximately one month.
7 C 9 B 11 A 13 C 15 B 17 B 19 B 21 A 23 D 25 B 27 C 29 B 31 The four types of tissue in the body are epithelial,
connective, muscle, and nervous. Epithelial tissue is made of layers of cells that cover the surfaces of the body that come into
contact with the exterior world, line internal cavities, and form glands. Connective tissue binds the cells and organs of the body
together and performs many functions, especially in the protection, support, and integration of the body. Muscle tissue, which
responds to stimulation and contracts to provide movement, is divided into three major types: skeletal (voluntary) muscles,
smooth muscles, and the cardiac muscle in the heart. Nervous tissue allows the body to receive signals and transmit information
as electric impulses from one region of the body to another. 33 Synovial membranes are a type of connective tissue membrane
that supports mobility in joints. The membrane lines the joint cavity and contains fibroblasts that produce hyaluronan, which leads
to the production of synovial fluid, a natural lubricant that enables the bones of a joint to move freely against one another. 35 Blood
is a fluid connective tissue, a variety of specialized cells that circulate in a watery fluid containing salts, nutrients, and dissolved
proteins in a liquid extracellular matrix. Blood contains formed elements derived from bone marrow. Erythrocytes, or red blood
cells, transport the gases oxygen and carbon dioxide. Leukocytes, or white blood cells, are responsible for the defense of the
organism against potentially harmful microorganisms or molecules. Platelets are cell fragments involved in blood clotting. Some
cells have the ability to cross the endothelial layer that lines vessels and enter adjacent tissues. Nutrients, salts, and waste are
dissolved in the liquid matrix and transported through the body. 37 The cells in the dish are cardiomyocytes, cardiac muscle
cells. They have an intrinsic ability to contract. When they link up, they form intercalating discs that allow the cells to communicate
with each other and begin contracting in synchrony. 39 Neurons are well suited for the transmission of nerve impulses because
short extensions, dendrites, receive impulses from other neurons, while a long tail extension, an axon, carries electrical impulses
away from the cell to other neurons. 41 These symptoms would indicate that infection is present. 43 The genetic makeup and the
lifestyle of each individual are factors which determine the degree of decline in cells, tissues, and organs as an individual ages.
Chapter 5
1 The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis (fat layer) provides insulation
and padding. 3 Figure 5.6 These cells have desmosomes, which give the cells their spiny appearance. 5 D 7 C 9 C 11 D 13
B 15 A 17 C 19 C 21 C 23 B 25 The pigment melanin, produced by melanocytes, is primarily responsible for skin color. Melanin
comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-
skinned individuals have a lighter shade of skin and less melanin. Exposure to UV irradiation stimulates the melanocytes to produce
and secrete more melanin. 27 Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They
release a watery sweat, mixed with some metabolic waste and antibodies. Apocrine glands are associated with hair follicles. They
are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis. They release a
thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor. 29 Sweating cools the body when
it becomes warm. When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the
sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating
heat. 31 Acne results from a blockage of sebaceous glands by sebum. The blockage causes blackheads to form, which are susceptible
to infection. The infected tissue then becomes red and inflamed. Teenagers experience this at high rates because the sebaceous
glands become active during puberty. Hormones that are especially active during puberty stimulate the release of sebum, leading
in many cases to blockages.
Chapter 6
1 B 3 C 5 B 7 B 9 A 11 C 13 B 15 C 17 C 19 A 21 D 23 D 25 B 27 B 29 D 31 C 33 A 35 A 37 D 39 B 40
It supports the body. The rigid, yet flexible skeleton acts as a framework to support the other organs of the body. It facilitates
movement. The movable joints allow the skeleton to change shape and positions; that is, move. It protects internal organs. Parts of
the skeleton enclose or partly enclose various organs of the body including our brain, ears, heart, and lungs. Any trauma to these
organs has to be mediated through the skeletal system. It produces blood cells. The central cavity of long bones is filled with
marrow. The red marrow is responsible for forming red and white blood cells. It stores and releases minerals and fat. The mineral
component of bone, in addition to providing hardness to bone, provides a mineral reservoir that can be tapped as needed.
This file is copyright 2022, Rice University. All Rights Reserved.
This file is copyright 2022, Rice University. All Rights Reserved.
,OpenStax Anatomy & Physiology 2e Student Answer Guide
ANSWER KEY
Chapter 1
1 Fatty acid catabolism. 3 X-rays. 5 PET scans can indicate how patients are responding to chemotherapy. 6 C 8 A 10 D 12
C 14 C 16 C 18 C 20 D 22 D 24 D 26 C 28 An understanding of anatomy and physiology is essential for any career in
the health professions. It can also help you make choices that promote your health, respond appropriately to signs of illness, make
sense of health-related news, and help you in your roles as a parent, spouse, partner, friend, colleague, and caregiver. 30 Chemical,
cellular, tissue, organ, organ system, organism. 32 When you are sitting at a campfire, your sense of smell adapts to the smell of
smoke. Only if that smell were to suddenly and dramatically intensify would you be likely to notice and respond. In contrast,
the smell of even a trace of smoke would be new and highly unusual in your residence hall, and would be perceived as danger. 34
In a sealed bottle of sparkling water, carbon dioxide gas is kept dissolved in the water under a very high pressure. When you open
the bottle, the pressure of the gas above the liquid changes from artificially high to normal atmospheric pressure. The dissolved
carbon dioxide gas expands, and rises in bubbles to the surface. When a bottle of sparkling water is left open, it eventually goes
flat because its gases continue to move out of solution until the pressure in the water is approximately equal to atmospheric pressure.
36 The four components of a negative feedback loop are: stimulus, sensor, control center, and effector. If too great a quantity of the
chemical were excreted, sensors would activate a control center, which would in turn activate an effector. In this case, the effector
(the secreting cells) would be adjusted downward. 38 If the body were supine or prone, the MRI scanner would move from top to
bottom to produce frontal sections, which would divide the body into anterior and posterior portions, as in “cutting” a deck of cards.
Again, if the body were supine or prone, to produce sagittal sections, the scanner would move from left to right or from right to left
to divide the body lengthwise into left and right portions. 40 CT scanning subjects patients to much higher levels of radiation than
X-rays, and should not be performed repeatedly.
Chapter 2
1 The mass number is the total number of protons and neutrons in the nucleus of an atom. 3 The water hydrolyses, or breaks,
the glycosidic bond, forming two monosaccharides. 4 D 6 A 8 B 10 C 12 B 14 A 16 C 18 A 20 B 22 D 24 B 26 A 28
B 30 D 32 B 33 These four elements—oxygen, carbon, hydrogen, and nitrogen—together make up more than 95 percent of
the mass of the human body, and the body cannot make elements, so it is helpful to have them in consumables. 35 Magnesium’s
12 electrons are distributed as follows: two in the first shell, eight in the second shell, and two in its valence shell. According to the
octet rule, magnesium is unstable (reactive) because its valence shell has just two electrons. It is therefore likely to participate in
chemical reactions in which it donates two electrons. 37 Water is a polar molecule. It has a region of weakly positive charge and
a region of weakly negative charge. These regions are attracted to ions as well as to other polar molecules. Oils are nonpolar,
and are repelled by water. 39 It is not. An exchange reaction might be AB + CD → AC + BD or AB + CD → AD + BC
. In all chemical reactions, including exchange reactions, the components of the reactants are identical to the components of the
products. A component present among the reactants cannot disappear, nor can a component not present in the reactants suddenly
appear in the products. 41 Lemon juice is one hundred times more acidic than orange juice. This means that lemon juice has a one
hundred-fold greater concentration of hydrogen ions. 43 Maltose contains 12 atoms of carbon, but only 22 atoms of hydrogen and
11 atoms of oxygen, because a molecule of water is removed during its formation via dehydration synthesis.
Chapter 3
1 Higher temperatures speed up diffusion because molecules have more kinetic energy at higher temperatures. 3 an enzyme 5 the
spindle 6 B 8 C 10 B 12 A 14 A 16 C 18 A 20 C 22 C 24 B 26 B 28 C 30 Only materials that are relatively small and
nonpolar can easily diffuse through the lipid bilayer. Large particles cannot fit in between the individual phospholipids that are
packed together, and polar molecules are repelled by the hydrophobic/nonpolar lipids that line the inside of the bilayer. 32 These
four phenomena are similar in the sense that they describe the movement of substances down a particular type of gradient. Osmosis
and diffusion involve the movement of water and other substances down their concentration gradients, respectively. Filtration
describes the movement of particles down a pressure gradient, and the movement of ions away from like charge describes their
movement down their electrical gradient. 34 Peroxisomes and lysosomes are both cellular organelles bound by lipid bilayer
membranes, and they both contain many enzymes. However, peroxisomes contain enzymes that detoxify substances by transferring
hydrogen atoms and producing H2O2, whereas the enzymes in lysosomes function to break down and digest various unwanted
materials. 36 During cell division, one cell divides to produce two new cells. In order for all of the cells in your body to maintain
a full genome, each cell must replicate its DNA before it divides so that a full genome can be allotted to each of its offspring cells.
If DNA replication did not take place fully, or at all, the offspring cells would be missing some or all of the genome. This could be
disastrous if a cell was missing genes necessary for its function and health. 38 Transcription is really a “copy” process and
translation is really an “interpretation” process, because transcription involves copying the DNA message into a very similar RNA
message whereas translation involves converting the RNA message into the very different amino acid message. The two processes
also differ in their location: transcription occurs in the nucleus and translation in the cytoplasm. The mechanisms by
This file is copyright 2022, Rice University. All Rights Reserved.
, OpenStax Anatomy & Physiology 2e Student Answer Guide
which the two processes are performed are also completely different: transcription utilizes polymerase enzymes to build mRNA
whereas translation utilizes different kinds of RNA to build protein. 40 A cyclin is one of the primary classes of cell cycle control
molecules, while a cyclin-dependent kinase (is one of a group of molecules that work together with cyclins to determine progression
past cell checkpoints. By interacting with many additional molecules, these triggers push the cell cycle forward unless prevented
from doing so by “stop” signals, if for some reason the cell is not ready. 42 Embryonic stem cells derive from human embryos,
which are destroyed to obtain the cells. The destruction of human embryos is an ethical problem. And, the DNA in an embryonic
stem cell would differ from the DNA of the person being treated, which could result in immune problems or rejected of tissue.
Chapter 4
1 Most somatic stem cells give rise to only a few cell types. 3 Skeletal muscle cells are striated. 5 Approximately one month.
7 C 9 B 11 A 13 C 15 B 17 B 19 B 21 A 23 D 25 B 27 C 29 B 31 The four types of tissue in the body are epithelial,
connective, muscle, and nervous. Epithelial tissue is made of layers of cells that cover the surfaces of the body that come into
contact with the exterior world, line internal cavities, and form glands. Connective tissue binds the cells and organs of the body
together and performs many functions, especially in the protection, support, and integration of the body. Muscle tissue, which
responds to stimulation and contracts to provide movement, is divided into three major types: skeletal (voluntary) muscles,
smooth muscles, and the cardiac muscle in the heart. Nervous tissue allows the body to receive signals and transmit information
as electric impulses from one region of the body to another. 33 Synovial membranes are a type of connective tissue membrane
that supports mobility in joints. The membrane lines the joint cavity and contains fibroblasts that produce hyaluronan, which leads
to the production of synovial fluid, a natural lubricant that enables the bones of a joint to move freely against one another. 35 Blood
is a fluid connective tissue, a variety of specialized cells that circulate in a watery fluid containing salts, nutrients, and dissolved
proteins in a liquid extracellular matrix. Blood contains formed elements derived from bone marrow. Erythrocytes, or red blood
cells, transport the gases oxygen and carbon dioxide. Leukocytes, or white blood cells, are responsible for the defense of the
organism against potentially harmful microorganisms or molecules. Platelets are cell fragments involved in blood clotting. Some
cells have the ability to cross the endothelial layer that lines vessels and enter adjacent tissues. Nutrients, salts, and waste are
dissolved in the liquid matrix and transported through the body. 37 The cells in the dish are cardiomyocytes, cardiac muscle
cells. They have an intrinsic ability to contract. When they link up, they form intercalating discs that allow the cells to communicate
with each other and begin contracting in synchrony. 39 Neurons are well suited for the transmission of nerve impulses because
short extensions, dendrites, receive impulses from other neurons, while a long tail extension, an axon, carries electrical impulses
away from the cell to other neurons. 41 These symptoms would indicate that infection is present. 43 The genetic makeup and the
lifestyle of each individual are factors which determine the degree of decline in cells, tissues, and organs as an individual ages.
Chapter 5
1 The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis (fat layer) provides insulation
and padding. 3 Figure 5.6 These cells have desmosomes, which give the cells their spiny appearance. 5 D 7 C 9 C 11 D 13
B 15 A 17 C 19 C 21 C 23 B 25 The pigment melanin, produced by melanocytes, is primarily responsible for skin color. Melanin
comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-
skinned individuals have a lighter shade of skin and less melanin. Exposure to UV irradiation stimulates the melanocytes to produce
and secrete more melanin. 27 Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They
release a watery sweat, mixed with some metabolic waste and antibodies. Apocrine glands are associated with hair follicles. They
are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis. They release a
thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor. 29 Sweating cools the body when
it becomes warm. When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the
sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating
heat. 31 Acne results from a blockage of sebaceous glands by sebum. The blockage causes blackheads to form, which are susceptible
to infection. The infected tissue then becomes red and inflamed. Teenagers experience this at high rates because the sebaceous
glands become active during puberty. Hormones that are especially active during puberty stimulate the release of sebum, leading
in many cases to blockages.
Chapter 6
1 B 3 C 5 B 7 B 9 A 11 C 13 B 15 C 17 C 19 A 21 D 23 D 25 B 27 B 29 D 31 C 33 A 35 A 37 D 39 B 40
It supports the body. The rigid, yet flexible skeleton acts as a framework to support the other organs of the body. It facilitates
movement. The movable joints allow the skeleton to change shape and positions; that is, move. It protects internal organs. Parts of
the skeleton enclose or partly enclose various organs of the body including our brain, ears, heart, and lungs. Any trauma to these
organs has to be mediated through the skeletal system. It produces blood cells. The central cavity of long bones is filled with
marrow. The red marrow is responsible for forming red and white blood cells. It stores and releases minerals and fat. The mineral
component of bone, in addition to providing hardness to bone, provides a mineral reservoir that can be tapped as needed.
This file is copyright 2022, Rice University. All Rights Reserved.
