Although scientists observe that an organ-
9 l$ G% P3 D3 n1 q' ]0 A/ w+ xism’s behavior falls into rhythmic patterns, : |; s3 s/ q! e- r, L5 c
they disagree about how these patterns are m- M* G: W1 @- K1 ^( ?# k
affected when the organism is transported to a
8 P q( |" ^5 Y(5) new environment. One experimenter, Brown,
0 F2 l1 ?# x- fbrought oysters from Connecticut waters to
% ^1 q1 _! z" M: n$ P1 AIllinois waters. She noted that the oysters ' @& G. y6 M+ V ~1 N) s9 C
initially opened their shells widest when it was
7 N: u! R9 k- ~ Vhigh tide in Connecticut, but that after fourteen
# ]# m9 M% S# S) b: ^(10)days their rhythms had adapted to the tide
3 G2 i& x( S6 Y0 Yschedule in Illinois. Although she could not : x: Y' O7 |) p# \
posit an unequivocal causal relationship ( x6 f' E: l% q
between behavior and environmental change,
4 e' I* _9 z: |Brown concluded that a change in tide schedule % h1 [7 D% U3 w/ J+ m
(15)is one of several possible exogenous influences
( M3 o1 s. F* t2 r$ t(those outside the organism) on the oysters’
4 z1 j4 ^: l, B. Orhythms. Another experimenter, Hamner, 1 b1 \ {8 N+ a/ X
however, discovered that hamsters from Cali- 3 ~7 w" s$ m9 [8 }$ F
fornia maintain their original rhythms even # z6 o. a1 q; E# `3 q# q
(20)at the South Pole. He concluded that endo- + `7 T/ S- S( o( v3 ~
genous influences (those inside the organism) 1 T3 L; X; j/ v5 y% |; `# {( V9 Q5 F
seem to affect an organism’s rhythmic behavior. ! F8 J4 f4 u2 t9 G/ r* t5 ]" U3 i
2 [9 n3 c8 |6 h' l$ \' g& i) q0 Y17. All of the following could be considered 0 f; Y5 O1 ?9 m! f; R# e; v9 r" J
examples of exogenous influences on an * V" o, I6 z, G8 E* `# A. S
organism EXCEPT the influence of the + P( v. w# c( N! Y% [# o+ {3 h
(A) level of a hormone on a field mouse’s readi- 3 k% X- u M9 b$ J( Q2 M+ n8 N: d
ness for mating
( z5 r$ V* o, f q; ^& J0 z3 t (B) temperature of a region on a bear’s hiber-
/ m7 |% n4 A% ]0 F5 a Lnation 8 y1 C, S# G% [) {# u2 G" {: n5 _
(C) salt level of a river on a fish’s migration
$ v7 s0 e+ i* u+ A1 V7 g: } (D) humidity of an area on a cat’s shedding of " S3 j9 K8 A6 q
its fur # h0 m& {/ ~1 K5 {4 O2 @- F
(E) proximity of an owl on a lizard’s searching
! y0 D; P, v! N1 k9 l for food 0 D- H' i+ p' f0 T/ x. d. c) s
- C0 ]( v, Y* J
18. Which of the following statements best describes 5 K5 s6 D! v* s$ G# |2 V
the conclusion drawn by Brown (lines 14-17)?
5 E& @5 ^3 L) Z/ A" f5 {/ { (A) A change in tide schedule is the primary
8 R$ q- O; H, F" z; x influence on an oyster’s rhythms.
' P9 X0 u. J! ~5 t6 b (B) A change in tide schedule may be an 0 \% W H4 }; i) h
important exogenous influence on an
6 l# H- N- v) K( M5 h- z oyster’s rhythms.
4 ^# p) ~. N) R( f" ?* n) r (C) Exogenous influences, such as a change in 1 P8 W- G0 `. w
tide schedule, seldom affect an oyster’s + M) c2 y5 f( P2 q3 E4 I L
rhythms. # f* H2 I( a' s: \! c8 q# i) A
(D) Endogenous influences have no effect on an 5 {" M& T7 A6 A. k# U
oyster’s rhythms. # B4 b! u& d1 z) l p; A" Y1 A
(E) Endogenous influences are the only ! F5 z0 e) ]3 h3 \' ]6 x
influences on an oyster’s rhythms. |