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(A) A
(B) B
(C) C
(D) D
(E) E
87. If a solution containing denatured DNA (as-
sume only one species of DNA) is cooled to
25
°C below its melting temperature, which
of the following would be expected to occur?
(A) Phosphate groups would leave the indi-
vidual bases.
(B) Annealing
(C) Adenine-thymine base pairs would
again form three intermolecular hydro-
gen bonds.
(D) The individual strands composing the
double helices will remain isolated and
irreversibly altered.
(E) Adenine will reliably base pair with
guanine and with thymine.

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Biology E/M Subject Test
265
ARCO
■ SAT II Subject Tests
w w w . p e t e r s o n s . c o m / a r c o
Questions 88–90 concern the physiology of muscle contraction. The diagram below represents a tracing
from a kymograph. The contraction pattern of a frog’s leg muscle is being studied. Under appropriate
experimental conditions, the muscle is repeatedly stimulated. Note the frequency of stimulation varies
throughout the first portion of the tracing.
88. The portion of the kymograph labeled D prob-
ably represents which of the following?
(A) Simple twitch
(B) Tetanus
(C) Latent period
(D) Relaxation period
(E) Fatigue
89. In part A of the kymograph, it is noted that
muscle movement does not occur immediately
with the application of the stimulus. Rather,
there exists a finite time period between the
application of the stimulus and the resultant
muscle contraction. This time period is known
as the
(A) simple twitch period
(B) latent period