BIOLOGY EXAM 1 (CHAPTERS 1-4)
QUESTIONS WITH VERIFIED
ANSWERS
If you are given a solution that has a pH of 8.5, what would be its concentration of
protons? What is the difference in proton concentration between this solution and
one that has a pH of 7? - ANSWER-1.0 X 10^-8.5 M or 3.2 X 10^-9 M. This is about
32 times less concentrated than a solution with pH 7.0 (1 X 10^-7).
Consider the reaction between carbon dioxide and water to form carbonic acid:
CO2(g) + H2O (l) <- -> CH2O3(aq)
In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate
ion, as follows:
CH2O3 (aq) <- -> H+(aq) + CHO3-(aq)
If an underwater volcano bubbled additional CO2 into the ocean, would this
sequence of reactions be driven to the left or the right? How would this affect the pH
of the ocean? - ANSWER-Would move to the right. There would be more protons so
the acidity of the ocean would increase. The dissociation reaction of carbonic acid
lowers the pH of the solution by releasing extra H+ into the solution.
When H2 and CO2 react, acetic acid can be formed spontaneously while the
production of formaldehyde requires an input of energy. Which of the following
conclusions may be drawn from this observation?
a) More heat is released when formaldehyde is produced compared to the
production of acetic acid.
b) Compared to the reactions that it is formed from, formaldehyde has more potential
energy than does acetic acid.
c) Entropy decreases when acetic acid is produced and increases when
formaldehyde is produced.
d) The mineral catalyst involved in acetic acid production provides energy to make
the reaction spontaneous. - ANSWER-b) compared to the reactions that is is formed
from, formaldehyde has more potential energy than does acetic acid.
From what you have learned about water, why do coastal regions tend to have
milder climates with cooler summers and warmer winters than do inland areas at the
same latitude? - ANSWER-In hot weather, water absorbs large amounts of heat due
to its high specific heat and high heat of vaporization. In cold weather, water
releases the large amount of heat that it has absorbed.
How do organisms survive below freezing temperatures? The winter flounder
(Pseudopleuronectes americanus) lives in the Mid-Atlantic Ocean and along the New
England coast, where frigid water temperatures would normally turn the water inside
the flounder's cells into ice. Does the flounder produce some type of antifreeze
compound that prevents it from freezing solid?
The flounder is able to survive in very cold water, but only when water is in its liquid
state. What property of water prevents the ocean from freezing solid when the
temperature in the air is well below water's freezing point? - ANSWER-Water is
, denser in its liquid form than its solid form. This results in ice floating on the surface
and serving as a blanket to insulate the liquid water from the colder temperature in
the air.
The salty ocean has a higher level of entropy compared to fresh water due to the
dissolved ions it contains, which interact with and disperse water molecules. For ice
to form in the ocean, this entropy must be reduced to allow the crystalline structure
shown in Figure 2.15a to form. If you were able to break off a piece of this ice and
melt it, would the water taste fresh or salty? Explain your answer. - ANSWER-The
water will taste fresh. The liquid water in the ocean forms the crystalline structure of
ice when water molecules interact with each other, excluding the salt ions.
Evaluate the following statements related to the process of freezing water:
T/F It does not follow the second law of thermodynamics.
T/F It is exothermic.
T/F It results in an overall increase in entropy.
T/F It requires an input of energy - ANSWER-F
T
T
F
P. Americanus produces a small antifreeze protein (AFP) that binds to ice crystals as
they form. The structure of AFP has polar groups on one side and non polar groups
on the other. Propose a hypothesis to explain how AFT prevents cells from freezing
solid. - ANSWER-One hypothesis might be that AFP binds to ice crystals and forms
a non polar shell that prevents hydrogen bonding between water molecules to form a
larger crystal. By limiting crystal growth, the cell would not freeze solid.
The flounder AFP has been used to genetically modify plants to reduce tissue
damage under freezing temperatures. The data from one experiment using a potato
plant are provided below. What additional information is needed to determine if AFP
is useful in protecting against frost damage? - ANSWER-To address the
effectiveness of AFP, you might ask, "How long did the investigators keep the plants
at each temperature?"
Engineering potatoes, tomatoes, and strawberries to produce the flounder AFP has
been a topic of heated debate. What do you think some of the pros and cons of
producing these genetically modified organisms might be? - ANSWER-A pro may be
the prevention of lost crops due to the abnormally cold weather that may occur due
to the climate change. A con may be the unexpected consequences in growth, taste,
or nutritional value of foods that contain AFP.
What two functional groups are bound to the central carbon of every free amino acid
monomer? - ANSWER-An amino group and a carboxyl group
If the researchers had compared vines growing under variable light conditions, how
might this have changed their interpretation of the data? - ANSWER-If different vines
were exposed to different light levels, this would add another variable to the study.
Under these varying conditions, changes in the herbivory index might be due to light
availability.
QUESTIONS WITH VERIFIED
ANSWERS
If you are given a solution that has a pH of 8.5, what would be its concentration of
protons? What is the difference in proton concentration between this solution and
one that has a pH of 7? - ANSWER-1.0 X 10^-8.5 M or 3.2 X 10^-9 M. This is about
32 times less concentrated than a solution with pH 7.0 (1 X 10^-7).
Consider the reaction between carbon dioxide and water to form carbonic acid:
CO2(g) + H2O (l) <- -> CH2O3(aq)
In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate
ion, as follows:
CH2O3 (aq) <- -> H+(aq) + CHO3-(aq)
If an underwater volcano bubbled additional CO2 into the ocean, would this
sequence of reactions be driven to the left or the right? How would this affect the pH
of the ocean? - ANSWER-Would move to the right. There would be more protons so
the acidity of the ocean would increase. The dissociation reaction of carbonic acid
lowers the pH of the solution by releasing extra H+ into the solution.
When H2 and CO2 react, acetic acid can be formed spontaneously while the
production of formaldehyde requires an input of energy. Which of the following
conclusions may be drawn from this observation?
a) More heat is released when formaldehyde is produced compared to the
production of acetic acid.
b) Compared to the reactions that it is formed from, formaldehyde has more potential
energy than does acetic acid.
c) Entropy decreases when acetic acid is produced and increases when
formaldehyde is produced.
d) The mineral catalyst involved in acetic acid production provides energy to make
the reaction spontaneous. - ANSWER-b) compared to the reactions that is is formed
from, formaldehyde has more potential energy than does acetic acid.
From what you have learned about water, why do coastal regions tend to have
milder climates with cooler summers and warmer winters than do inland areas at the
same latitude? - ANSWER-In hot weather, water absorbs large amounts of heat due
to its high specific heat and high heat of vaporization. In cold weather, water
releases the large amount of heat that it has absorbed.
How do organisms survive below freezing temperatures? The winter flounder
(Pseudopleuronectes americanus) lives in the Mid-Atlantic Ocean and along the New
England coast, where frigid water temperatures would normally turn the water inside
the flounder's cells into ice. Does the flounder produce some type of antifreeze
compound that prevents it from freezing solid?
The flounder is able to survive in very cold water, but only when water is in its liquid
state. What property of water prevents the ocean from freezing solid when the
temperature in the air is well below water's freezing point? - ANSWER-Water is
, denser in its liquid form than its solid form. This results in ice floating on the surface
and serving as a blanket to insulate the liquid water from the colder temperature in
the air.
The salty ocean has a higher level of entropy compared to fresh water due to the
dissolved ions it contains, which interact with and disperse water molecules. For ice
to form in the ocean, this entropy must be reduced to allow the crystalline structure
shown in Figure 2.15a to form. If you were able to break off a piece of this ice and
melt it, would the water taste fresh or salty? Explain your answer. - ANSWER-The
water will taste fresh. The liquid water in the ocean forms the crystalline structure of
ice when water molecules interact with each other, excluding the salt ions.
Evaluate the following statements related to the process of freezing water:
T/F It does not follow the second law of thermodynamics.
T/F It is exothermic.
T/F It results in an overall increase in entropy.
T/F It requires an input of energy - ANSWER-F
T
T
F
P. Americanus produces a small antifreeze protein (AFP) that binds to ice crystals as
they form. The structure of AFP has polar groups on one side and non polar groups
on the other. Propose a hypothesis to explain how AFT prevents cells from freezing
solid. - ANSWER-One hypothesis might be that AFP binds to ice crystals and forms
a non polar shell that prevents hydrogen bonding between water molecules to form a
larger crystal. By limiting crystal growth, the cell would not freeze solid.
The flounder AFP has been used to genetically modify plants to reduce tissue
damage under freezing temperatures. The data from one experiment using a potato
plant are provided below. What additional information is needed to determine if AFP
is useful in protecting against frost damage? - ANSWER-To address the
effectiveness of AFP, you might ask, "How long did the investigators keep the plants
at each temperature?"
Engineering potatoes, tomatoes, and strawberries to produce the flounder AFP has
been a topic of heated debate. What do you think some of the pros and cons of
producing these genetically modified organisms might be? - ANSWER-A pro may be
the prevention of lost crops due to the abnormally cold weather that may occur due
to the climate change. A con may be the unexpected consequences in growth, taste,
or nutritional value of foods that contain AFP.
What two functional groups are bound to the central carbon of every free amino acid
monomer? - ANSWER-An amino group and a carboxyl group
If the researchers had compared vines growing under variable light conditions, how
might this have changed their interpretation of the data? - ANSWER-If different vines
were exposed to different light levels, this would add another variable to the study.
Under these varying conditions, changes in the herbivory index might be due to light
availability.
