6. Because adult iguanas on Plazos Island are much smaller than adult iguanas of the same species on nearby islands, researchers assumed that environmental conditions on Plazos favor the survival of relatively smaller baby iguanas (hatchlings) in each yearly brood. They discovered instead that for each of the past three years, 10 percent of the smaller and 40 percent of the larger hatchlings survived, because larger hatchlings successfully evade their predators.</p> Which of the following, if true about Plazos but not about nearby islands, contributes most to an explanation of the long-standing tendency of iguanas on Plazos to be smaller than those of the same age on nearby islands?
$ \* t% a4 k! B8 W( ^ (A) Periodic wind shifts cause extended dry spells on Plazos every year, putting the larger iguanas, whose bodies require relatively more water, at a great disadvantage., D2 I- p* }, i V: F
(B) There are exactly three species of iguanas on Plazos but only two species of seagulls that feed on iguanas, and a relatively small percentage of each year's hatchlings are consumed by seagulls., T2 A P; t- Z' j+ a$ x' r# T" ?
(C) Wild cats, which were introduced as pets by early settlers and which were formerly major predators of Plazos iguanas, were recently killed off by a disease specific to cats.' `% H9 E3 u. D/ g4 x
(D) The iguanas on Plazos are a relatively ancient part of the island's animal life.! V" |6 [! f- j8 p
(E) Both land and marine iguanas live on Plazos,and the land iguanas tend to be larger than marine iguanas of the same age.- L) e S4 h6 N2 V
7. Every human being who has ever lived had two parents. Therefore, more people were alive three thousand years ago than are alive now.The reasoning in the argument is flawed because it8 G/ e" U6 i* d+ L5 |1 j E
(A) overlooks the number of people in each generation during the last three thousand years who left no descendants
, k: o. v4 N7 I& n (B) disregards possible effects of disasters such as famines and plagues on human history
1 \/ u+ ^* [+ o0 [/ i! ~" ^ (C) overestimates the mathematical effect of repeated doublings on population size( O, L/ o) Z$ o9 O4 ?& T; j
(D) fails to take into account that people now alive have overlapping sets of ancestors
8 @& ~; ?* D" [! C( S0 }! I7 Z (E) fails to consider that accurate estimation of the number of people alive three thousand years ago might be impossible
7 R$ ?6 C" @ p( U Q6 [7 G) Z 8. Each of the academic journals Thought and Ergo has a review committee to prevent misattributed quotations from appearing in its published articles. Nevertheless, about ten percent of the quotations in Thought's published articles are misattributed, whereas Ergo contains no misattributions. Ergo's committee is more effective, therefore, than Thought's at finding misattributed quotations.# K1 O, V) q* v+ V/ P& t3 g
The argument above assumes that
+ b7 t$ z" }% t1 `$ a$ W4 k (A) most of the articles submitted to Thought for publication contain misattributed quotations
6 j( z( S$ w, c4 M' {) O$ a8 | (B) there are at least some misattributed quotations in articles submitted to Ergo for publication% i) E: _1 F: H/ r, x
(C) the members of Ergo's committee are, on the whole, more knowledgeable than are the members of Thought's committee
; ?9 C- {5 A) X9 u- Y2 U4 o (D) the number of misattributed quotations in a journal is an accurate measure of how carefully that journal is edited; b5 E; u9 E" O/ G1 O; b
(E) the authors who submit articles to Ergo for publication are more thorough in attributing quotations than are the authors who submit articles to Thought7 [+ C) ^% r0 n# l) R2 H0 B/ R
9. In the last few decades, grassy wetlands, essential to the nesting and breeding of ducks, geese, swans, and most other species of waterfowl, have been extensively drained and cultivated in southern Canada and the northern United States,Duck populations in North American have plummeted during this time, but populations of swans and geese have been affected less dramatically.
8 I6 Q; y q( g% J" l7 d; I Which of the following, if true, most helps to explain the difference mentioned above?
0 ^* C$ \' X! H' D (A) Prohibition of hunting of waterfowl is easier to enforce in areas under cultivation than in wild lands.7 J! m! s9 j: V" X4 h/ L
(B) Most geese and swans nest and breed farther north than ducks do, in areas that still are not cultivated.
6 Q1 o) P. p2 p6 Y% _' X (C) Land that has been harvested rarely provides food suitable for waterfowl.
6 q% u: }. `/ o/ i, u9 W" k (D) Goose and swan populations decline in periods of drought, when breeding sites are fewer.
) \4 c* T; { L( H( e (E) Because they are larger than ducks, geese and swans have a harder time finding protected nesting sites in areas that are cultivated. |