Suggested Answers to Collaborative Questions Biology, 4th edition By Brooker et,
al.
Chapter 1
1. Most biologists would say that theories are true, but maybe students who are new to the
discipline don’t feel the same way. There are a variety of ways to decide if things are true:
experimentation, logic, hearing it from experts, faith, etc. This discussion may be interesting
because it may help you decide how you determine whether or not things are true. Maybe
you’ve never thought about this before.
2. The male and female alligators don’t have different genomes. Somehow, temperature
affects the proteome. There are a lot of possible things that could happen. For example,
higher temperature could cause a protein that is needed for female development to unfold
and not work properly. The main idea is that temperature affects protein structure and
function and thereby influences the proteome. Some proteins regulate genes and control the
genome. If these proteins were affected by temperature, they could control which proteins
are made at high and low temperatures.
Chapter 2
1. Protons—These are positively charged particles that are found in the center of the atom
which is referred to as the nucleus. The number of protons an atom has is called the atomic
number, and this defines each type of element. This particle makes up approximately half of
the mass of an atom, which is referred to as the atomic mass.
Neutrons—These are neutral (uncharged) particles that are found in the nucleus of the
atom. For most atoms of biological importance, the number of neutrons is equal to the
number of protons in an atom, but this is not always the case. Atoms with the same number
of protons but different numbers of neutrons are called isotopes of each other.
Electrons—These are negatively charged particles that are found in orbitals around the
nucleus. For atoms, the number of protons is equal to the number of electrons. Therefore, an
atom has no overall net charge. If electrons are added to an atom or taken away, this will
change the charge of the atom, which is now called an ion, thereby changing its properties
and reactivity.
2. The partial electric charges around the hydrogen and oxygen atoms in a water molecule
make water a good solvent for many of the chemicals important for life in organisms, such
as ions and polar compounds.
Water can directly participate in types of chemical reactions called hydrolysis reactions,
which among other things are important in the conversion of certain large molecules into
smaller units that are biologically important.
Water has a high heat of vaporization, which means that it takes a great deal of heat to
change its state from a liquid to a gas. As a result of this, most of the water in our planet is
in liquid form, which is required to support life.
Water also has a high heat of fusion and requires a great deal of energy to be removed from
it to turn it from a liquid to a solid. As a result of this, liquid water is very stable and resistant
to temperature change, making it ideal for living organisms.
Also see Figure 2.19.
Chapter 3
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
,1. Monosaccharides—These are monomers and the most simple of the sugars,
carbohydrates that often, but not always, taste sweet. A prime example of this type of sugar
is glucose, which is used by many organisms in the production of ATP.
Disaccharides—These consist of two monosaccharides covalently bonded together. Sucrose
is an example of this type of sugar. This is accomplished through a dehydration reaction by
removing hydrogen from one monosaccharide and a hydroxyl from the other, resulting in
the loss of a molecule of water.
Polysaccharides—These are polymers that consist of many monosaccharides bonded
together. Some examples of polysaccharides are
Glycogen—this is the storage form of glucose in animals.
Starch—this is the storage form of glucose in plants.
Cellulose—this molecule serves as a support molecule in plants.
2. Protection—protect organisms from attack against disease. Organisms develop specific
proteins to fight against specific diseases.
Enzymes—increase the rates of chemical reactions. Without these proteins, metabolism
would slow down and stop.
Gene expression and regulation—involved in transcribing genes (converting DNA into RNA),
regulating the activity of genes, and synthesizing polypeptides.
Cell signaling—needed for a cell to communicate with other cells and with the environment.
Motor proteins—allow cellular movements.
Transporters—allow the movement of ions and molecules across cellular membranes.
Chapter 4
1. The term genome refers to the entire genetic complement of a cell, which codes for all of
the proteins that a cell can produce. If a cell needs to manufacture a protein, it must get the
instructions on how to build it from the DNA, which is found inside the nucleus. The
proteome is the entire collection of proteins that a cell can make. The production of proteins
inside the cell is very dynamic and constantly changing inside the cell based on current
conditions in and out of the cell. During different times of a cell’s life, it will be required to
make different proteins based on the current function of the cell. This is accomplished by
accessing different genes from the DNA of the cell.
Within each cell is the entire genetic complement of the organism, yet each individual cell
will use only part of it to produce the proteins it needs.
2. See Figures 4.5 and 4.7 for how the nucleus, ER, and Golgi are arranged relative to each
other. The nucleus and ER are continuous with each other. The two membranes of the
nuclear envelop meet at the nuclear pores. The ER and Golgi share material via membrane
vesicles.
Chapter 5
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
, 1. Perhaps the main reason why plasma membrane proteins are good targets for drugs is
because the drug doesn’t have to get into the cell to affect the protein’s function. Also,
plasma membrane proteins play a variety of important roles in the structure and function of
cells, making them good targets for drugs. To determine if any particular plasma membrane
protein is the target of a drug, you need to have a method to determine if the protein is
working properly. For example, if a protein transports glucose into the cell, you need to have
a method to measure glucose uptake. In this case, you could add radiolabeled glucose
outside the cell and monitor its uptake over time. If you thought a drug was affecting such a
glucose transporter, the rate of glucose uptake would be determined in the presence and
absence of the drug. If the glucose transporter was the target of the drug, you would expect
the drug to have an effect on the rate of glucose transport.
2. Simple diffusion: The main advantage is that a cell doesn’t have to expend any energy to
transport the solute. The disadvantages are that it’s not very specific, and it cannot achieve
active transport.
Facilitated diffusion: The advantage is that it can specifically move solutes across the
membrane down their gradients. The disadvantage is that it cannot achieve active
transport.
Active transport: The advantages are that it can specifically move solutes across a
membrane and it can move them against a gradient. A disadvantage is that it uses up
energy in the process.
Endocytosis: The main advantage is that it can move large things across the membrane. A
disadvantage would be that it is a pretty complicated process, which uses a lot of cellular
components.
Chapter 6
1. Living cells acquire energy to maintain their internal order. This energy comes in different
forms. Light energy powers photosynthesis, which then supplies organic molecules that
store and release energy. Living cells are not defying the second law of thermodynamics
because the law applies to the whole universe. Although cells are highly ordered, the
maintenance of cell order increases the net entropy of the universe. For example, cells give
off heat, which affects the disorder of their surroundings.
2. Having a common energy source allows a cell to make fewer proteins and thereby keep
its biochemical composition simpler. It would take a lot of energy to make a Na_/K_-ATPase,
a Na_/K-glucosase, a Na_/ K-sucrase, and a Na_/K_-fatty acidase. Also, having fewer proteins
allows a species to have a smaller genome, which improves efficiency.
Chapter 7
1. Compared to most forms of anaerobic respiration and fermentation, an advantage of
aerobic respiration is that it generates more ATP. However, a disadvantage is that it requires
oxygen which may not be available or, in the case of muscle exertion, may be used up very
quickly. The main advantage of anaerobic respiration and fermentation is that cells can keep
making ATP even if oxygen is not available.
2. Solid tumors, such as those found in lung cancer and liver cancer, are most readily
detected via PET scans. The level of hypoxia within a solid tumor is thought to affect the
detection. The center regions of a tumor are often hypoxic, which means they are deficient
in oxygen. This hypoxia occurs because of an inadequate blood supply. The hypoxia tends to
induce the genes that encode the enzymes of glycolysis, which, in turn, increases the level
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
al.
Chapter 1
1. Most biologists would say that theories are true, but maybe students who are new to the
discipline don’t feel the same way. There are a variety of ways to decide if things are true:
experimentation, logic, hearing it from experts, faith, etc. This discussion may be interesting
because it may help you decide how you determine whether or not things are true. Maybe
you’ve never thought about this before.
2. The male and female alligators don’t have different genomes. Somehow, temperature
affects the proteome. There are a lot of possible things that could happen. For example,
higher temperature could cause a protein that is needed for female development to unfold
and not work properly. The main idea is that temperature affects protein structure and
function and thereby influences the proteome. Some proteins regulate genes and control the
genome. If these proteins were affected by temperature, they could control which proteins
are made at high and low temperatures.
Chapter 2
1. Protons—These are positively charged particles that are found in the center of the atom
which is referred to as the nucleus. The number of protons an atom has is called the atomic
number, and this defines each type of element. This particle makes up approximately half of
the mass of an atom, which is referred to as the atomic mass.
Neutrons—These are neutral (uncharged) particles that are found in the nucleus of the
atom. For most atoms of biological importance, the number of neutrons is equal to the
number of protons in an atom, but this is not always the case. Atoms with the same number
of protons but different numbers of neutrons are called isotopes of each other.
Electrons—These are negatively charged particles that are found in orbitals around the
nucleus. For atoms, the number of protons is equal to the number of electrons. Therefore, an
atom has no overall net charge. If electrons are added to an atom or taken away, this will
change the charge of the atom, which is now called an ion, thereby changing its properties
and reactivity.
2. The partial electric charges around the hydrogen and oxygen atoms in a water molecule
make water a good solvent for many of the chemicals important for life in organisms, such
as ions and polar compounds.
Water can directly participate in types of chemical reactions called hydrolysis reactions,
which among other things are important in the conversion of certain large molecules into
smaller units that are biologically important.
Water has a high heat of vaporization, which means that it takes a great deal of heat to
change its state from a liquid to a gas. As a result of this, most of the water in our planet is
in liquid form, which is required to support life.
Water also has a high heat of fusion and requires a great deal of energy to be removed from
it to turn it from a liquid to a solid. As a result of this, liquid water is very stable and resistant
to temperature change, making it ideal for living organisms.
Also see Figure 2.19.
Chapter 3
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
,1. Monosaccharides—These are monomers and the most simple of the sugars,
carbohydrates that often, but not always, taste sweet. A prime example of this type of sugar
is glucose, which is used by many organisms in the production of ATP.
Disaccharides—These consist of two monosaccharides covalently bonded together. Sucrose
is an example of this type of sugar. This is accomplished through a dehydration reaction by
removing hydrogen from one monosaccharide and a hydroxyl from the other, resulting in
the loss of a molecule of water.
Polysaccharides—These are polymers that consist of many monosaccharides bonded
together. Some examples of polysaccharides are
Glycogen—this is the storage form of glucose in animals.
Starch—this is the storage form of glucose in plants.
Cellulose—this molecule serves as a support molecule in plants.
2. Protection—protect organisms from attack against disease. Organisms develop specific
proteins to fight against specific diseases.
Enzymes—increase the rates of chemical reactions. Without these proteins, metabolism
would slow down and stop.
Gene expression and regulation—involved in transcribing genes (converting DNA into RNA),
regulating the activity of genes, and synthesizing polypeptides.
Cell signaling—needed for a cell to communicate with other cells and with the environment.
Motor proteins—allow cellular movements.
Transporters—allow the movement of ions and molecules across cellular membranes.
Chapter 4
1. The term genome refers to the entire genetic complement of a cell, which codes for all of
the proteins that a cell can produce. If a cell needs to manufacture a protein, it must get the
instructions on how to build it from the DNA, which is found inside the nucleus. The
proteome is the entire collection of proteins that a cell can make. The production of proteins
inside the cell is very dynamic and constantly changing inside the cell based on current
conditions in and out of the cell. During different times of a cell’s life, it will be required to
make different proteins based on the current function of the cell. This is accomplished by
accessing different genes from the DNA of the cell.
Within each cell is the entire genetic complement of the organism, yet each individual cell
will use only part of it to produce the proteins it needs.
2. See Figures 4.5 and 4.7 for how the nucleus, ER, and Golgi are arranged relative to each
other. The nucleus and ER are continuous with each other. The two membranes of the
nuclear envelop meet at the nuclear pores. The ER and Golgi share material via membrane
vesicles.
Chapter 5
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
, 1. Perhaps the main reason why plasma membrane proteins are good targets for drugs is
because the drug doesn’t have to get into the cell to affect the protein’s function. Also,
plasma membrane proteins play a variety of important roles in the structure and function of
cells, making them good targets for drugs. To determine if any particular plasma membrane
protein is the target of a drug, you need to have a method to determine if the protein is
working properly. For example, if a protein transports glucose into the cell, you need to have
a method to measure glucose uptake. In this case, you could add radiolabeled glucose
outside the cell and monitor its uptake over time. If you thought a drug was affecting such a
glucose transporter, the rate of glucose uptake would be determined in the presence and
absence of the drug. If the glucose transporter was the target of the drug, you would expect
the drug to have an effect on the rate of glucose transport.
2. Simple diffusion: The main advantage is that a cell doesn’t have to expend any energy to
transport the solute. The disadvantages are that it’s not very specific, and it cannot achieve
active transport.
Facilitated diffusion: The advantage is that it can specifically move solutes across the
membrane down their gradients. The disadvantage is that it cannot achieve active
transport.
Active transport: The advantages are that it can specifically move solutes across a
membrane and it can move them against a gradient. A disadvantage is that it uses up
energy in the process.
Endocytosis: The main advantage is that it can move large things across the membrane. A
disadvantage would be that it is a pretty complicated process, which uses a lot of cellular
components.
Chapter 6
1. Living cells acquire energy to maintain their internal order. This energy comes in different
forms. Light energy powers photosynthesis, which then supplies organic molecules that
store and release energy. Living cells are not defying the second law of thermodynamics
because the law applies to the whole universe. Although cells are highly ordered, the
maintenance of cell order increases the net entropy of the universe. For example, cells give
off heat, which affects the disorder of their surroundings.
2. Having a common energy source allows a cell to make fewer proteins and thereby keep
its biochemical composition simpler. It would take a lot of energy to make a Na_/K_-ATPase,
a Na_/K-glucosase, a Na_/ K-sucrase, and a Na_/K_-fatty acidase. Also, having fewer proteins
allows a species to have a smaller genome, which improves efficiency.
Chapter 7
1. Compared to most forms of anaerobic respiration and fermentation, an advantage of
aerobic respiration is that it generates more ATP. However, a disadvantage is that it requires
oxygen which may not be available or, in the case of muscle exertion, may be used up very
quickly. The main advantage of anaerobic respiration and fermentation is that cells can keep
making ATP even if oxygen is not available.
2. Solid tumors, such as those found in lung cancer and liver cancer, are most readily
detected via PET scans. The level of hypoxia within a solid tumor is thought to affect the
detection. The center regions of a tumor are often hypoxic, which means they are deficient
in oxygen. This hypoxia occurs because of an inadequate blood supply. The hypoxia tends to
induce the genes that encode the enzymes of glycolysis, which, in turn, increases the level
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without
the prior written consent of McGraw-Hill Education
