Biology Exam 1 (chapters 1-4)
Questions with Verified Answers
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.
What was the purpose of including bare tree trunks in the study? - ANSWER-Bare
tree trunks were included in the study as a control to show that the vine was not
protected merely by climbing up a support to avoid predators on the ground.
By avoiding being eaten, B. trifoliolata individuals would have increased fitness. In
biology, what does the term "fitness" mean? - ANSWER-"Fitness" refers to an
individual's ability to survive and reproduce.
Which of the following occurs when a covalent bond forms? - ANSWER-Electrons in
valence shells are shared between atoms.
If a reaction is exothermic, then which of the following statements is always true? -
ANSWER-The products have lower potential energy than the reactants.
Which of the following is most likely to have supplied the energy needed for the
formation of acetic acid in deep-sea hydrothermal vents? - ANSWER-Chemical
energy stored in reactants
What factors determine whether a chemical reaction is spontaneous or not? -
ANSWER-Potential energy and entropy
Which of the following molecules would you predict to have the largest number of
polar covalent bonds based on their molecular formulas?
a) C2H6O (ethanol)
b) C2H6 (ethane)
c) C2H4O2 (acetic acid)
d) C3H80 (propanol) - ANSWER-C) Acetic acid has more highly electronegative
oxygen atoms than the other molecules. When oxygen is bonded to carbon or
hydrogen, a polar covalent bond forms.
Locate fluorine (F) on the partial periodic table provided in Figure 2.2. Predict its
relative electronegativity compared to hydrogen, sodium and oxygen. State the
number and type of bond(s) you expect it would form if it reacted with sodium (Na). -
ANSWER-Relative electronegativities would be F>O>H>Na. One bond would form
with sodium, and it would be ionic.
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
Questions with Verified Answers
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.
What was the purpose of including bare tree trunks in the study? - ANSWER-Bare
tree trunks were included in the study as a control to show that the vine was not
protected merely by climbing up a support to avoid predators on the ground.
By avoiding being eaten, B. trifoliolata individuals would have increased fitness. In
biology, what does the term "fitness" mean? - ANSWER-"Fitness" refers to an
individual's ability to survive and reproduce.
Which of the following occurs when a covalent bond forms? - ANSWER-Electrons in
valence shells are shared between atoms.
If a reaction is exothermic, then which of the following statements is always true? -
ANSWER-The products have lower potential energy than the reactants.
Which of the following is most likely to have supplied the energy needed for the
formation of acetic acid in deep-sea hydrothermal vents? - ANSWER-Chemical
energy stored in reactants
What factors determine whether a chemical reaction is spontaneous or not? -
ANSWER-Potential energy and entropy
Which of the following molecules would you predict to have the largest number of
polar covalent bonds based on their molecular formulas?
a) C2H6O (ethanol)
b) C2H6 (ethane)
c) C2H4O2 (acetic acid)
d) C3H80 (propanol) - ANSWER-C) Acetic acid has more highly electronegative
oxygen atoms than the other molecules. When oxygen is bonded to carbon or
hydrogen, a polar covalent bond forms.
Locate fluorine (F) on the partial periodic table provided in Figure 2.2. Predict its
relative electronegativity compared to hydrogen, sodium and oxygen. State the
number and type of bond(s) you expect it would form if it reacted with sodium (Na). -
ANSWER-Relative electronegativities would be F>O>H>Na. One bond would form
with sodium, and it would be ionic.
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
