Although scientists observe that an organ- ! U- e' }) c& u% Q( U1 ^* L
ism’s behavior falls into rhythmic patterns, ; N8 C( Z x: e- ]3 ~! V: z9 V- L
they disagree about how these patterns are % R- `% d1 P9 P8 m
affected when the organism is transported to a ' \1 t/ V4 q4 l: [& p( H/ ?
(5) new environment. One experimenter, Brown, + I7 d* Y m: t2 P2 G& n
brought oysters from Connecticut waters to
7 w. n" e, h" R7 uIllinois waters. She noted that the oysters 9 m7 Q: c' U: \4 X
initially opened their shells widest when it was " z1 E! A+ Z1 G5 [' Y, G- G9 S
high tide in Connecticut, but that after fourteen ! ]% R0 _0 Y7 n8 @" E+ ?
(10)days their rhythms had adapted to the tide
' T) T4 y+ L& Lschedule in Illinois. Although she could not 0 z3 _+ s. \2 W. b2 O
posit an unequivocal causal relationship 0 \8 z. l5 D5 g1 ~* j$ p4 W" i# [- Z+ Z
between behavior and environmental change,
i# u8 D0 @) \# b4 ^/ P, bBrown concluded that a change in tide schedule 1 o1 R2 j. X' x" K! H7 O1 e6 f
(15)is one of several possible exogenous influences ' _% J+ z$ y4 y3 O" O8 A( Z
(those outside the organism) on the oysters’
# I, W: Z% ~" Q% w5 E( a0 Hrhythms. Another experimenter, Hamner,
, d O* H+ g/ H% j( Y1 P# Whowever, discovered that hamsters from Cali-
% `0 R2 \6 A, }* F. yfornia maintain their original rhythms even 9 a. u, U4 r3 @% I" |
(20)at the South Pole. He concluded that endo-
3 L1 z0 O- ^* b8 X Sgenous influences (those inside the organism) 1 m4 N; @: w3 i' g* M3 j
seem to affect an organism’s rhythmic behavior. 3 p- h, F& \$ a3 a! u$ d
) ]* d) h& ]1 g$ b @17. All of the following could be considered # e5 z: [, Y* Q
examples of exogenous influences on an 5 h8 @/ q* k; T1 P' h2 i- Y
organism EXCEPT the influence of the
2 L2 H$ t2 y6 u8 N+ _ (A) level of a hormone on a field mouse’s readi- # e8 ~6 ]: X9 h* e8 }, ~
ness for mating
4 i9 @* C5 Z3 _; @' s( d" g (B) temperature of a region on a bear’s hiber-
: \; F: K6 t4 S) X" k# _" P( {nation
5 z# |/ w8 y% Q (C) salt level of a river on a fish’s migration i; V& s% l, q& K" D- x
(D) humidity of an area on a cat’s shedding of
- d( o7 j% S5 K8 @0 m its fur s7 v1 c/ |6 b: M2 z
(E) proximity of an owl on a lizard’s searching S/ l& D1 Q9 o
for food ' O) b7 c9 Z) G" k" K/ c- e( k2 x# R
) I) `) T% H5 }" ]! n18. Which of the following statements best describes
6 B* r* Y @0 |* kthe conclusion drawn by Brown (lines 14-17)?
; r, G# u9 @" a+ z (A) A change in tide schedule is the primary 6 W3 w: A. R& e) I P8 N
influence on an oyster’s rhythms.
/ f$ N9 M! S& k! `" o (B) A change in tide schedule may be an + k! d* i2 s9 b# J( q
important exogenous influence on an
4 [/ h+ V7 b+ [1 |0 Y- h. c oyster’s rhythms.
+ N2 g3 Y2 [+ r* x: A (C) Exogenous influences, such as a change in 8 g% E2 |+ @5 [$ W" T1 l0 ]
tide schedule, seldom affect an oyster’s / H- V! g& I# C0 @* a8 d
rhythms. ' S+ Z. F* |4 f
(D) Endogenous influences have no effect on an
4 N7 d; o* Q, F4 z2 D- w- doyster’s rhythms. + w+ U! N' ^3 [8 I
(E) Endogenous influences are the only % L. ]4 C- X& a0 _
influences on an oyster’s rhythms. |