Testbank for Biology 2nd Edition from OpenStax College ISBN 9781947172517Chapter 1 1 Figure 1.6 1: C; 2: F; 3: A; 4: B; 5: D; 6: E. The original hypothesis is incorrect, as the coffeemaker works when plugged into the outlet. Alternative hypotheses include that the toaster might be broken or that th...
Chapter 1
1 Figure 1.6 1: C; 2: F; 3: A; 4: B; 5: D; 6: E. The original hypothesis is incorrect, as the
coffeemaker works when plugged into the outlet. Alternative hypotheses include that the
toaster might be broken or that the toaster wasn't turned on.
3 Figure 1.16 Communities exist within populations which exist within ecosystems.
4B
6D
8C
10 C
12 B
14 D
16 Answers will vary, but should apply the steps of the scientific method. One
possibility could be a car which doesn’t start. The hypothesis could be that the car
doesn’t start because the battery is dead. The experiment would be to change the
battery or to charge the battery and then check whether the car starts or not. If it starts,
the problem was due to the battery, and the hypothesis is accepted.
18 Answers will vary. Topics that fall inside the area of biological study include how
diseases affect human bodies, how pollution impacts a species’ habitat, and how plants
respond to their environments. Topics that fall outside of biology (the “study of life”)
include how metamorphic rock is formed and how planetary orbits function.
20 Answers will vary. Layers of sedimentary rock have order but are not alive.
Technology is capable of regulation but is not, of itself, alive.
22 During your walk, you may begin to perspire, which cools your body and helps your
body to maintain a constant internal temperature. You might also become thirsty and
pause long enough for a cool drink, which will help to restore the water lost during
perspiration.
Chapter 2
1 Figure 2.3 Carbon-12 has six neutrons. Carbon-13 has seven neutrons.
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,3. Figure 2.24 C
3 A
6 C
8 D
10C
12
D
14 Ionic bonds are created between ions. The electrons are not shared between the
atoms, but rather are associated more with one ion than the other. Ionic bonds are
strong bonds, but are weaker than covalent bonds, meaning it takes less energy to
break an ionic bond compared with a covalent one.
16 Buffers absorb the free hydrogen ions and hydroxide ions that result from chemical
reactions. Because they can bond these ions, they prevent increases or decreases in
pH. An example of a buffer system is the bicarbonate system in the human body. This
system is able to absorb hydrogen and hydroxide ions to prevent changes in pH and
keep cells functioning properly.
18 Carbon is unique and found in all living things because it can form up to four
covalent bonds between atoms or molecules. These can be nonpolar or polar
covalent bonds, and they allow for the formation of long chains ofcarbon molecules that
combine to form proteins and DNA.
Chapter 3
1 Figure 3.5 Glucose and galactose are aldoses. Fructose is a ketose.
3 Figure 3.33 Adenine is larger than cytosine and will not be able to base pair properly
with the guanine on the opposing strand. This will cause the DNA to bulge. DNA repair
enzymes may recognize the bulge and replace the incorrect nucleotide.
4C
6A
8D
10 B
12 D
14 C
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, 16 B
18 C
20 C
21 Biological macromolecules are organic because they contain carbon.
23 Amino acids can be linked into long chains through condensation reactions. One of
the hydrogen atoms bonded to the nitrogen atom of an amino acid reacts with the –OH
group attached to the terminal carbon on another amino acid. Since both ends of the
molecule can participate in condensation reactions, peptide bonds can be made in
both directions to create a long amino acid chain.
25 The β 1-4 glycosidic linkage in cellulose cannot be broken down by human digestive
enzymes. Herbivores such as cows, koalas, and buffalos are able to digest grass that is
rich in cellulose and use it as a food source because bacteria and protists in their
digestive systems, especially in the rumen, secrete the enzyme cellulase. Cellulases
can break down cellulose into glucose monomers that can be used as an energy
source by the animal.
27 Fat serves as a valuable way for animals to store energy. It can also provide
insulation. Waxes can protect plant leaves and mammalian fur from getting wet.
Phospholipids and steroids are important components of animal cell membranes, as
well as plant, fungal, and bacterial membranes.
29 Fats have a higher energy density than carbohydrates (averaging 9kcal/gram versus
4.3kcal/gram respectively). Thus, on a per gram basis, more energy can be stored in
fats than can be stored in carbohydrates. Additionally, fats are packaged into spherical
globules to minimize interactions with the water-based plasma membrane, while
glycogen is a large branched carbohydrate that cannot be compacted for storage.
31 A change in gene sequence can lead to a different amino acid being added to a
polypeptide chain instead of the normal one. This causes a change in protein structure
and function. For example, in sickle cell anemia, the hemoglobin β chain has a single
amino acid substitution—the amino acid glutamic acid in position six is substituted by
valine. Because of this change, hemoglobin molecules form aggregates, and the disc-
shaped red blood cells assume a crescent shape, which results in serious health
problems.
33 The protein must form a channel in the plasma membrane that allows water into the
cell since water cannot cross the plasma membrane by itself. Since aquaporins are
embedded in the plasma membrane and connect with both the intracellular and
extracellular spaces, it must be amphipathic like the plasma membrane. The top and
bottom of the protein must contain charged or polar amino acids (hydrophilic) to interact
with the aqueous environments. The exterior transmembrane region must contain non-
polar amino acids (hydrophobic) that can interact with the phospholipid tail. However,
the inside of this channel must contain hydrophilic amino acids since they will interact
with the traveling water molecules.
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