Solutions Manual For Understanding
Biology 4th Edition By Kenneth Mason,
Tod Duncan, Jonathan Losos (All
Chapters 100% Original Verified A+
Grade)
SM 1: Answers Synthesize Questions
SM 2: Analysis Answers Final
,Part 1
Understanding Biology, 4th edition by Mason, Duncan, and Losos
Answers to End-of-Chapter Synthesize Questions
Chapter 1
1. 1 1021 (0.10) (0.0001) (1 10 −6 ) = 1,000,000,000 planets could support intelligent life. There are
many possible explanations for not “hearing from” other intelligent life forms. Some possibilities
include: (1) Different forms of intelligent life have different levels of awareness of other possible life
forms (so they do not know if we exist either); (2) The reasons we have not made contact with them
also explain why they have not made contact with us (cost of space exploration, distance to other life-
sustaining planets, etc.); (3) Other intelligent life forms constitute a planet full of animals, or dinosaurs,
or insects, far, far away. These life forms are not likely try to make “contact”; and (4) The other plants
in our universe that support life are still in the earlier stages of developing life—similar to stages on
Earth before life as we know it. Just because a planet can support life does not mean that it does or
will.
2. The organism level is the lowest level of hierarchical organization that carries out all of the activities we
associate with life. An organism might be a single cell (bacterial cells are organized, grow and
reproduce, possess genetic information, acquire and use energy, and maintain homeostasis); but this is
not characteristic of all individual cells.
3. Probably not. The plants and animals Darwin saw on the Galapagos Islands were interesting to Darwin
because they did not resemble the plants and animals of islands with similar climates. In this way, they
provided evidence that plants and animals were not created independently and then placed on the
Galapagos Islands, but rather arrived from the South American mainland. The plants and animals on
the Cape Verde Islands would be more likely to resemble those on mainland Africa rather than those
on the Galapagos Islands.
4. For something to be considered living, it would demonstrate organization, possibly including a cellular
structure. The organism would acquire and use materials and energy to maintain homeostasis, respond
to its environment, and to grow and reproduce. These latter properties, and evidence of genetic
material and evolution, might be difficult to determine if the evidence of life from other planets is
fossil evidence.
Chapter 2
1. 6480 years (The sample would contain 8 mg in 1620 years, 4 mg in 3240 years, 2 mg 4860 years, and 1
mg in 6480 years).
2. This is likely so because so much of the body is composed of water, and most of the mass of that water
is attributed to oxygen ( 16 of 18 g/mol ).
3. Stable molecules are built from stable covalent bonds. Covalent bonds are stable because they have no
net charge, satisfy the octet rule, and result in no unpaired electrons. Ionic bonds are not directional,
and thus are not truly between two individual atoms. This means that ionic bonds do not form distinct
molecules and are thus not the basis of stable molecules because they are not the basis of molecules at
all.
4. Silicon theoretically has the same bonding chemistry as carbon. Its atomic number is 14; it has four
unpaired valence electrons; its atomic mass is less than 21 (like the other elements involved in the
formation of biological compounds). However, silicon when silicon forms the structures that carbon
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
, does (rings, branched chains, etc.), they are unstable and often reactive. If it was able to form diverse,
stable compounds (like carbon), it might be a good candidate for an alternative molecule upon which
to base life.
5. On Earth, we literally find living things anywhere there is liquid water. The key properties of water that
would support its role as evidence of life include: 1) its ability to act as a solvent, which can allow for
the transport of dissolved molecules that can form other complex molecules; 2) its resistance to
changes in temperature, which can serve to protect molecules or organisms within it from
temperature extremes; and 3) its ability to form a less dense solid than its liquid form, which can help
to maintain a liquid environment beneath a frozen environment.
6. When liquids like colas and champagne are consumed, the acids dissolved in them are neutralized by
buffers (like bicarbonate) in the body that take up the excess hydrogen to prevent any harm being
caused by the acidity.
Chapter 3
1. This remains an open question. Ideas fall into two general categories: chemical and biological. The
chemical hypotheses seek a chemical mechanism for the observed asymmetry. Biological hypotheses
seek a form of selective pressure to produce the asymmetry. It could also be an “accident” where a
temporary excess resulted in selection for one enantiomer.
2. No, the enzymes that synthesize starch would not be expected to be the same as those that synthesize
cellulose. Enzymes are specific with respect to the substrates they interact with. While starch and
cellulose are both polymers of glucose the monomer subunits are actually different. Starches consist of
chains of -glucose, while cellulose consists of -glucose chains. These monomers are stereoisomers,
and enzymes can be stereospecific. So, even though the reaction would be the same, a dehydration
reaction between glucose monomers, the -glucose and -glucose monomers would require different
enzymes. It is possible that the enzyme would both be derived from a common ancestral enzyme, but
the modern enzymes would be expected to be different.
3. The final structure of a protein is determined by its primary structure (the chemical nature of its side
groups), but several configurations are still possible. Chaperonin proteins have been shown to ensure
that proper folding occurs such that issues like clumping and diseases that might result from improper
folding.
4. A sequence like TATATATATATAT, or TAATTAATATATA, which contain only adenine and thymine. Base
pairs between A and T form only two hydrogen bonds, whereas base pairs between G and C form three
hydrogen bonds. This means A/T rich sequences melt more easily.
5. A high percentage of unsaturated fatty acids, which resist forming solids because their fatty acid chains
bend and cannot become closely associated like saturated fatty acids; long chains (16-20 carbons),
because this is what is generally seen in membrane phospholipids.
Chapter 4
1. The flat version of the single-celled organism would have a greater surface area over which to bring
materials in and expel wastes out. In the flattened version, the distance from the inside of the cell to
the outside would also be decreased, increasing the rate at which this transport could take place.
2. Examine the cell wall: if it contains peptidoglycan, it is a bacterium. You could also look at the
membrane lipids: archaea would have glycerol-1-phosphate and ether linked isoprenoid units.
3. The nuclear envelope would not break down / rebuild during cell division. It is likely that cell division
would not proceed normally.
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
, 4. Although a chloroplast has its own DNA, external membranes, and is capable of synthesizing sugars, it
cannot survive on its own. Some of the genes that code for its components are actually found in the
nucleus of the cell it is a part of, so it could not reproduce on its own. The chloroplast also relies on
energy produced by the cell’s mitochondria.
5. It is possible that mutations amplified the 9 + 2 structure and it then differentiated to function in
several structures.
Chapter 5
1. The polarity of proteins makes this model problematic. If the proteins simply covered the phospholipid
bilayer, they would be exposed to a hydrophilic environment on all sides, which is an unstable
configuration.
2. There are several ways that this can be done. New membrane lipids are synthesized in the ER, and
when they are transported to the Golgi or plasma membrane, the insertion of new lipids could
introduce asymmetries. Membrane phospholipids could also be “flipped” from one layer to the other
by enzymes to create asymmetries.
3. Binding of a signaling molecule can change the conformation of the receptor protein, this can affect
the cytoplasmic domain. This allows signals to be transmitted without any molecule crossing the
membrane.
4. The bilayer is not freely permeable to most polar substances; however water can move across the
membrane at a low rate. This is greatly increased by aquaporins, which are water channels. There are
no ammonia channels.
5. Perhaps because these pumps are already expending so much of the cell’s energy it was energetically
efficient to couple the transport of other molecules to the transport of protons, sodium, and
potassium. It could also be the case that these transport proteins evolved early, and the presence of
gradients created by these proteins, cells adapted to transport other proteins using these as an energy
source.
6. Plant cells use this process to move things from within the cell membrane to the cell wall, for instance,
the materials needed to build the cell wall itself.
Chapter 6
1. No. Laws of thermodynamics refer to closed systems. Despite the notion that the natural tendency of
the universe is an increase in entropy, this increase results from spontaneous reactions (through which
energy is lost). However, not every reaction that takes place in the universe is spontaneous. Some
reactions actually create order, using energy to reorganize (for instance, those that build
macromolecules from smaller subunits) the world. This reorganization does not result in an increase in
entropy.
2. Yes it is likely that the production of light from the firefly, which involves chemical reaction, requires
some form of energy in the form of ATP, which was likely synthesized by the organism’s cells, within
the mitochondria, in the same manner in which other organisms’ cells produce energy (using glucose
and oxygen). To test this hypothesis, one might attempt to quantify the products of cellular respiration
(carbon dioxide, water, and heat) in the firefly or deny the firefly an oxygenated environment to see if
it is still able to produce as much light when its cells are forced to undergo anaerobic respiration.
3. 40 ° C seems to be the optimum temperature for the protein. Above this temperature, the protein
structure is denatured. Since form and function are intertwined, a denatured enzyme does not
function, as demonstrated by the drop off in reaction rate above 40° C.
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
Biology 4th Edition By Kenneth Mason,
Tod Duncan, Jonathan Losos (All
Chapters 100% Original Verified A+
Grade)
SM 1: Answers Synthesize Questions
SM 2: Analysis Answers Final
,Part 1
Understanding Biology, 4th edition by Mason, Duncan, and Losos
Answers to End-of-Chapter Synthesize Questions
Chapter 1
1. 1 1021 (0.10) (0.0001) (1 10 −6 ) = 1,000,000,000 planets could support intelligent life. There are
many possible explanations for not “hearing from” other intelligent life forms. Some possibilities
include: (1) Different forms of intelligent life have different levels of awareness of other possible life
forms (so they do not know if we exist either); (2) The reasons we have not made contact with them
also explain why they have not made contact with us (cost of space exploration, distance to other life-
sustaining planets, etc.); (3) Other intelligent life forms constitute a planet full of animals, or dinosaurs,
or insects, far, far away. These life forms are not likely try to make “contact”; and (4) The other plants
in our universe that support life are still in the earlier stages of developing life—similar to stages on
Earth before life as we know it. Just because a planet can support life does not mean that it does or
will.
2. The organism level is the lowest level of hierarchical organization that carries out all of the activities we
associate with life. An organism might be a single cell (bacterial cells are organized, grow and
reproduce, possess genetic information, acquire and use energy, and maintain homeostasis); but this is
not characteristic of all individual cells.
3. Probably not. The plants and animals Darwin saw on the Galapagos Islands were interesting to Darwin
because they did not resemble the plants and animals of islands with similar climates. In this way, they
provided evidence that plants and animals were not created independently and then placed on the
Galapagos Islands, but rather arrived from the South American mainland. The plants and animals on
the Cape Verde Islands would be more likely to resemble those on mainland Africa rather than those
on the Galapagos Islands.
4. For something to be considered living, it would demonstrate organization, possibly including a cellular
structure. The organism would acquire and use materials and energy to maintain homeostasis, respond
to its environment, and to grow and reproduce. These latter properties, and evidence of genetic
material and evolution, might be difficult to determine if the evidence of life from other planets is
fossil evidence.
Chapter 2
1. 6480 years (The sample would contain 8 mg in 1620 years, 4 mg in 3240 years, 2 mg 4860 years, and 1
mg in 6480 years).
2. This is likely so because so much of the body is composed of water, and most of the mass of that water
is attributed to oxygen ( 16 of 18 g/mol ).
3. Stable molecules are built from stable covalent bonds. Covalent bonds are stable because they have no
net charge, satisfy the octet rule, and result in no unpaired electrons. Ionic bonds are not directional,
and thus are not truly between two individual atoms. This means that ionic bonds do not form distinct
molecules and are thus not the basis of stable molecules because they are not the basis of molecules at
all.
4. Silicon theoretically has the same bonding chemistry as carbon. Its atomic number is 14; it has four
unpaired valence electrons; its atomic mass is less than 21 (like the other elements involved in the
formation of biological compounds). However, silicon when silicon forms the structures that carbon
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
, does (rings, branched chains, etc.), they are unstable and often reactive. If it was able to form diverse,
stable compounds (like carbon), it might be a good candidate for an alternative molecule upon which
to base life.
5. On Earth, we literally find living things anywhere there is liquid water. The key properties of water that
would support its role as evidence of life include: 1) its ability to act as a solvent, which can allow for
the transport of dissolved molecules that can form other complex molecules; 2) its resistance to
changes in temperature, which can serve to protect molecules or organisms within it from
temperature extremes; and 3) its ability to form a less dense solid than its liquid form, which can help
to maintain a liquid environment beneath a frozen environment.
6. When liquids like colas and champagne are consumed, the acids dissolved in them are neutralized by
buffers (like bicarbonate) in the body that take up the excess hydrogen to prevent any harm being
caused by the acidity.
Chapter 3
1. This remains an open question. Ideas fall into two general categories: chemical and biological. The
chemical hypotheses seek a chemical mechanism for the observed asymmetry. Biological hypotheses
seek a form of selective pressure to produce the asymmetry. It could also be an “accident” where a
temporary excess resulted in selection for one enantiomer.
2. No, the enzymes that synthesize starch would not be expected to be the same as those that synthesize
cellulose. Enzymes are specific with respect to the substrates they interact with. While starch and
cellulose are both polymers of glucose the monomer subunits are actually different. Starches consist of
chains of -glucose, while cellulose consists of -glucose chains. These monomers are stereoisomers,
and enzymes can be stereospecific. So, even though the reaction would be the same, a dehydration
reaction between glucose monomers, the -glucose and -glucose monomers would require different
enzymes. It is possible that the enzyme would both be derived from a common ancestral enzyme, but
the modern enzymes would be expected to be different.
3. The final structure of a protein is determined by its primary structure (the chemical nature of its side
groups), but several configurations are still possible. Chaperonin proteins have been shown to ensure
that proper folding occurs such that issues like clumping and diseases that might result from improper
folding.
4. A sequence like TATATATATATAT, or TAATTAATATATA, which contain only adenine and thymine. Base
pairs between A and T form only two hydrogen bonds, whereas base pairs between G and C form three
hydrogen bonds. This means A/T rich sequences melt more easily.
5. A high percentage of unsaturated fatty acids, which resist forming solids because their fatty acid chains
bend and cannot become closely associated like saturated fatty acids; long chains (16-20 carbons),
because this is what is generally seen in membrane phospholipids.
Chapter 4
1. The flat version of the single-celled organism would have a greater surface area over which to bring
materials in and expel wastes out. In the flattened version, the distance from the inside of the cell to
the outside would also be decreased, increasing the rate at which this transport could take place.
2. Examine the cell wall: if it contains peptidoglycan, it is a bacterium. You could also look at the
membrane lipids: archaea would have glycerol-1-phosphate and ether linked isoprenoid units.
3. The nuclear envelope would not break down / rebuild during cell division. It is likely that cell division
would not proceed normally.
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
, 4. Although a chloroplast has its own DNA, external membranes, and is capable of synthesizing sugars, it
cannot survive on its own. Some of the genes that code for its components are actually found in the
nucleus of the cell it is a part of, so it could not reproduce on its own. The chloroplast also relies on
energy produced by the cell’s mitochondria.
5. It is possible that mutations amplified the 9 + 2 structure and it then differentiated to function in
several structures.
Chapter 5
1. The polarity of proteins makes this model problematic. If the proteins simply covered the phospholipid
bilayer, they would be exposed to a hydrophilic environment on all sides, which is an unstable
configuration.
2. There are several ways that this can be done. New membrane lipids are synthesized in the ER, and
when they are transported to the Golgi or plasma membrane, the insertion of new lipids could
introduce asymmetries. Membrane phospholipids could also be “flipped” from one layer to the other
by enzymes to create asymmetries.
3. Binding of a signaling molecule can change the conformation of the receptor protein, this can affect
the cytoplasmic domain. This allows signals to be transmitted without any molecule crossing the
membrane.
4. The bilayer is not freely permeable to most polar substances; however water can move across the
membrane at a low rate. This is greatly increased by aquaporins, which are water channels. There are
no ammonia channels.
5. Perhaps because these pumps are already expending so much of the cell’s energy it was energetically
efficient to couple the transport of other molecules to the transport of protons, sodium, and
potassium. It could also be the case that these transport proteins evolved early, and the presence of
gradients created by these proteins, cells adapted to transport other proteins using these as an energy
source.
6. Plant cells use this process to move things from within the cell membrane to the cell wall, for instance,
the materials needed to build the cell wall itself.
Chapter 6
1. No. Laws of thermodynamics refer to closed systems. Despite the notion that the natural tendency of
the universe is an increase in entropy, this increase results from spontaneous reactions (through which
energy is lost). However, not every reaction that takes place in the universe is spontaneous. Some
reactions actually create order, using energy to reorganize (for instance, those that build
macromolecules from smaller subunits) the world. This reorganization does not result in an increase in
entropy.
2. Yes it is likely that the production of light from the firefly, which involves chemical reaction, requires
some form of energy in the form of ATP, which was likely synthesized by the organism’s cells, within
the mitochondria, in the same manner in which other organisms’ cells produce energy (using glucose
and oxygen). To test this hypothesis, one might attempt to quantify the products of cellular respiration
(carbon dioxide, water, and heat) in the firefly or deny the firefly an oxygenated environment to see if
it is still able to produce as much light when its cells are forced to undergo anaerobic respiration.
3. 40 ° C seems to be the optimum temperature for the protein. Above this temperature, the protein
structure is denatured. Since form and function are intertwined, a denatured enzyme does not
function, as demonstrated by the drop off in reaction rate above 40° C.
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.
