Following are suggested answers to the “Think Like a Scien琀椀st” short answer ques琀椀ons that appear in
the Unanswered Ques琀椀ons ac琀椀vi琀椀es included in the MindTap for Biology: The Dynamic Science, 5e.
Please note: these ac琀椀vi琀椀es are located in the Ac琀椀vity Builder. To see a list of ac琀椀vi琀椀es, please search on
“Unanswered Ques琀椀ons” from within the Ac琀椀vity Builder.
Unanswered Ques琀椀ons: How Will Marine Ecosystems be A昀昀ected by Climate Change and Ocean
Acidi昀椀ca琀椀on? (Chapter 2)
1. Describe both local and global strategies for protec琀椀ng marine ecosystems from ocean acidi昀椀ca琀椀on
and climate change. What experiments and studies could be performed to track the success of these
strategies and maximize their e昀昀ec琀椀veness?
Suggested answer: Local strategies such as reducing pollu琀椀on, over昀椀shing,
coastal development, and destruc琀椀ve 昀椀shing prac琀椀ces, o昀琀en by se琀�ng up networks of well-managed
marine protected areas, have been shown to make marine ecosystems more resilient to global stressors
such as climate change. Global strategies to reduce impacts of ocean acidi昀椀ca琀椀on and climate change
should be focused on reducing CO2 levels in the atmosphere, which is a major global poli琀椀cal and social
challenge. Addi琀椀onal global strategies could include large mul琀椀na琀椀onal networks of marine reserves,
bioengineering strategies for CO2 storage or sequestra琀椀on, and global trea琀椀es to ensure that global CO2
levels are reduced quickly enough to avoid major ecosystem-level damage. Experiments and studies to
track the e昀昀ec琀椀veness of these e昀昀orts could include: (1) rapid, global monitoring studies to study the
health of marine ecosystems at a rate su昀케cient for adap琀椀ve management; (2) mul琀椀stressor, mul琀椀scale
experiments so that we can be琀琀er understand impacts from the molecular to the ecosystem level; and
(3) molecular and physiological studies so that we can determine the mechanisms of the impacts and
develop strategies to reduce impacts.
1
,Unanswered Ques琀椀ons: How Are the Enzymes That Synthesize Fa琀琀y Acids and Cholesterol Regulated
in the Cells? (Chapter 3)
1. Defects in SREBP regula琀椀on contribute to common diseases, ranging from heart a琀琀acks to obesity and
diabetes. How might be琀琀er understanding of the SREBP regulatory mechanism contribute to treatment
of diabetes?
Suggested answer: In type 2 diabetes, SREBPs in the liver are ac琀椀vated, and this leads to overproduc琀椀on
of fa琀琀y acids and triglycerides. Inhibitors of SREBP processing might reduce plasma triglycerides and
prevent their toxic e昀昀ects on blood vessels.
Unanswered Ques琀椀ons: Understanding Cells (Chapter 4)
1. There are several major approaches cell biologists use to inves琀椀gate complex cell structures and
processes. One is to perturb the ac琀椀vity of genes or proteins and assess the e昀昀ect on cellular func琀椀on.
Another is to build or recons琀椀tute the structure or process in a test tube. What are strengths and
weaknesses of each approach? What types of ques琀椀ons can be answered using one or the other? Can
you think of technical challenges that might arise for each one?
Suggested answer: Perturbing the ac琀椀vity of individual genes and proteins allows cell biologists to
determine whether each plays a necessary role in a given cellular process, but does not indicate what
mechanis琀椀c role the protein performs or how it cooperates with other proteins to perform its func琀椀ons.
On the other hand, recons琀椀tu琀椀ng a process in a test tube allows cell biologists to build a func琀椀oning
system from individual components and understand how each contributes to the system, but does not
address the func琀椀onal importance of each component in the context of the cell. Both approaches can be
technically challenging, but recons琀椀tu琀椀on is o昀琀en more challenging because it requires both
iden琀椀昀椀ca琀椀on of all of the important players and the isola琀椀on of the players in a func琀椀onal form.
2
, Unanswered Ques琀椀ons: How Do Aquaporin Channels Func琀椀on? (Chapter 5)
1. Why do you think it is func琀椀onal that the water channels in the cell membrane formed by aquaporins
restrict the passage of protons?
Suggested answer: Restric琀椀ng the passage of protons aids in conserva琀椀on of the membrane’s
electrochemical poten琀椀al.
Unanswered Ques琀椀ons: The RNA World Hypothesis (Chapter 6)
1. Could a single cataly琀椀c RNA molecule replicate itself? Keep in mind that it needs to template the
synthesis of every nucleo琀椀de in its sequence by base-pairing, which includes the nucleo琀椀des of its
cataly琀椀c center.
Suggested answer: The problem is that each nucleo琀椀de in the ribozyme would need to serve as
template for polymeriza琀椀on. This means that the ribozyme would have to open up its own structure and
inac琀椀vate its own cataly琀椀c site. Therefore, the existence of such a molecule seems very unlikely.
However, it may be possible to design such a molecule if it has two cataly琀椀c centers, or if the crucial
parts of the ribozyme do not need to template because they exist twice in the molecule.
Unanswered Ques琀椀ons: Cellular Metabolism and Alzheimer’s Disease (Chapter 7)
1. What signi昀椀cance do you a琀琀ribute to the statement in this essay that changes in the levels of many
mitochondrial proteins occurs early in AD, before the development of signi昀椀cant plaque and tangle
pathologies? Develop a scien琀椀昀椀c hypothesis based on this statement.
Suggested answer: One possible hypothesis: there is a direct cause and e昀昀ect rela琀椀onship between
altered regula琀椀on of mitochondrial expression and AD. If a signi昀椀cant number of mice whose genes
were not gene琀椀cally altered were to develop AD, this hypothesis would have to be rejected.
3
the Unanswered Ques琀椀ons ac琀椀vi琀椀es included in the MindTap for Biology: The Dynamic Science, 5e.
Please note: these ac琀椀vi琀椀es are located in the Ac琀椀vity Builder. To see a list of ac琀椀vi琀椀es, please search on
“Unanswered Ques琀椀ons” from within the Ac琀椀vity Builder.
Unanswered Ques琀椀ons: How Will Marine Ecosystems be A昀昀ected by Climate Change and Ocean
Acidi昀椀ca琀椀on? (Chapter 2)
1. Describe both local and global strategies for protec琀椀ng marine ecosystems from ocean acidi昀椀ca琀椀on
and climate change. What experiments and studies could be performed to track the success of these
strategies and maximize their e昀昀ec琀椀veness?
Suggested answer: Local strategies such as reducing pollu琀椀on, over昀椀shing,
coastal development, and destruc琀椀ve 昀椀shing prac琀椀ces, o昀琀en by se琀�ng up networks of well-managed
marine protected areas, have been shown to make marine ecosystems more resilient to global stressors
such as climate change. Global strategies to reduce impacts of ocean acidi昀椀ca琀椀on and climate change
should be focused on reducing CO2 levels in the atmosphere, which is a major global poli琀椀cal and social
challenge. Addi琀椀onal global strategies could include large mul琀椀na琀椀onal networks of marine reserves,
bioengineering strategies for CO2 storage or sequestra琀椀on, and global trea琀椀es to ensure that global CO2
levels are reduced quickly enough to avoid major ecosystem-level damage. Experiments and studies to
track the e昀昀ec琀椀veness of these e昀昀orts could include: (1) rapid, global monitoring studies to study the
health of marine ecosystems at a rate su昀케cient for adap琀椀ve management; (2) mul琀椀stressor, mul琀椀scale
experiments so that we can be琀琀er understand impacts from the molecular to the ecosystem level; and
(3) molecular and physiological studies so that we can determine the mechanisms of the impacts and
develop strategies to reduce impacts.
1
,Unanswered Ques琀椀ons: How Are the Enzymes That Synthesize Fa琀琀y Acids and Cholesterol Regulated
in the Cells? (Chapter 3)
1. Defects in SREBP regula琀椀on contribute to common diseases, ranging from heart a琀琀acks to obesity and
diabetes. How might be琀琀er understanding of the SREBP regulatory mechanism contribute to treatment
of diabetes?
Suggested answer: In type 2 diabetes, SREBPs in the liver are ac琀椀vated, and this leads to overproduc琀椀on
of fa琀琀y acids and triglycerides. Inhibitors of SREBP processing might reduce plasma triglycerides and
prevent their toxic e昀昀ects on blood vessels.
Unanswered Ques琀椀ons: Understanding Cells (Chapter 4)
1. There are several major approaches cell biologists use to inves琀椀gate complex cell structures and
processes. One is to perturb the ac琀椀vity of genes or proteins and assess the e昀昀ect on cellular func琀椀on.
Another is to build or recons琀椀tute the structure or process in a test tube. What are strengths and
weaknesses of each approach? What types of ques琀椀ons can be answered using one or the other? Can
you think of technical challenges that might arise for each one?
Suggested answer: Perturbing the ac琀椀vity of individual genes and proteins allows cell biologists to
determine whether each plays a necessary role in a given cellular process, but does not indicate what
mechanis琀椀c role the protein performs or how it cooperates with other proteins to perform its func琀椀ons.
On the other hand, recons琀椀tu琀椀ng a process in a test tube allows cell biologists to build a func琀椀oning
system from individual components and understand how each contributes to the system, but does not
address the func琀椀onal importance of each component in the context of the cell. Both approaches can be
technically challenging, but recons琀椀tu琀椀on is o昀琀en more challenging because it requires both
iden琀椀昀椀ca琀椀on of all of the important players and the isola琀椀on of the players in a func琀椀onal form.
2
, Unanswered Ques琀椀ons: How Do Aquaporin Channels Func琀椀on? (Chapter 5)
1. Why do you think it is func琀椀onal that the water channels in the cell membrane formed by aquaporins
restrict the passage of protons?
Suggested answer: Restric琀椀ng the passage of protons aids in conserva琀椀on of the membrane’s
electrochemical poten琀椀al.
Unanswered Ques琀椀ons: The RNA World Hypothesis (Chapter 6)
1. Could a single cataly琀椀c RNA molecule replicate itself? Keep in mind that it needs to template the
synthesis of every nucleo琀椀de in its sequence by base-pairing, which includes the nucleo琀椀des of its
cataly琀椀c center.
Suggested answer: The problem is that each nucleo琀椀de in the ribozyme would need to serve as
template for polymeriza琀椀on. This means that the ribozyme would have to open up its own structure and
inac琀椀vate its own cataly琀椀c site. Therefore, the existence of such a molecule seems very unlikely.
However, it may be possible to design such a molecule if it has two cataly琀椀c centers, or if the crucial
parts of the ribozyme do not need to template because they exist twice in the molecule.
Unanswered Ques琀椀ons: Cellular Metabolism and Alzheimer’s Disease (Chapter 7)
1. What signi昀椀cance do you a琀琀ribute to the statement in this essay that changes in the levels of many
mitochondrial proteins occurs early in AD, before the development of signi昀椀cant plaque and tangle
pathologies? Develop a scien琀椀昀椀c hypothesis based on this statement.
Suggested answer: One possible hypothesis: there is a direct cause and e昀昀ect rela琀椀onship between
altered regula琀椀on of mitochondrial expression and AD. If a signi昀椀cant number of mice whose genes
were not gene琀椀cally altered were to develop AD, this hypothesis would have to be rejected.
3
