302 ❯ STEP 5. Build Your Test-Taking Confidence
- B—Because thicker enamel in this species indi-
cates foods that are more difficult to process, the
answer is B. Answer E is incorrect because our
model has no predictive power; if the food
resources change, the enamel thickness may as
well, to either a thicker orthinner average (enamel
thickness could also stay the same). - B—Experimental setups where individuals are
given a choice as to where to move are called
“choice chambers.” - D—All the answers except D are possible, and
are important things to consider when setting
up an experiment. For example, it is important
to allow your study animals enough time to
move and/or get used to their new surroundings
and conditions before drawing conclusions about
their behavior. D is not a good answer because
half of the slugs started in a high-temperature
area and haven’t moved. - A—Kinesis is the movement of animals in
response to current conditions; animals tend to
move until they find a favorable environment, at
which point their movement slows. - D—It is important to try to measure only one
variable at once. The 18 slugs may have moved
to the higher-temperature, higher-salinity condi-
tions because they need high temperatures to
survive, even if they dislike high salinity, and vice
versa. The original experiment circumvents this
problem by giving a choice for all the possible
combinations of variables. Answer E is an inter-
esting issue, but two individuals is probably too
small a number to warrant throwing away the
study results. - C—New genes are introduced into the bac-
terium through viral transduction.
54. B—When the body has too little water, ADH
works to increase the amount of water available.
This drive to maintain a stable condition is an
example of homeostasis.
55. C—Line C showed no net change in weight,
indicating the concentration of the solution
inside the bag was the same (isotonic) as the
solution in the beaker.
56. A—The most water would diffuse into the most
hypertonic solution; line A shows the biggest
increase in weight.
57. B—Line B still shows an increase in weight at
50 minutes, whereas line A has leveled out and is
isotonic at 50 minutes.
58. C—Even though an amino acid doesn’t have
direct contact with the substrate, it still plays a
role in the overall shape of the enzyme.
59. A—As RNA polymerase adds new nucleotides to
the 3′end of the new strand, it is moving toward
the 5′end of the (antiparallel) template strand.
60. B—The promoter would be located upstream
from where transcription would begin.
61. C—There are few nucleotide differences
between species 1 and 2, indicating they would
reside close to one another on the cladogram.
The same holds true for species 3 and 5. There
are large numbers of differences between species
4 and all others, indicating it would be posi-
tioned on its own branch.
62. A—Both B and E branches originate from point 1.
63. C—Species B and C reside the closest to one
another.