Passage Reading and English Comprehension

Some people say that the best defense is a good offense; an octopus, however, would disagree. In addition to being one of the strangest and most beautiful creatures in nature, the octopus has some of the most inventive and effective defense mechanisms imaginable. While other animals have teeth, horns, or claws to help defend them from predators, the octopus concentrates its energy on hiding from and confusing its attackers. When it wants to get away, the octopus has an impressive arsenal of tricks at its disposal.

The most well-known of the octopus’s defense mechanisms is its ability to squirt clouds of ink into the water. Some octopi use this cloud of ink as camouflage; after squirting the ink, the octopus retreats into the ink cloud where the predator cannot see it. Other octopi use the ink cloud as a decoy. If a large, intelligent predator such as a shark knows that octopi use ink clouds for camouflage, it might simply attack the ink cloud blindly, hoping to make contact with the octopus inside. However, some sneaky octopi will release the ink cloud in one direction and scurry away in another direction, leaving the predator with nothing but a mouthful of ink. In addition to confusing predators’ sense of sight, these ink clouds also confuse their sense of smell. The ink is composed primarily of melanin (the same chemical that gives human skin its color), which can shut down a predator’s sense of smell. If an octopus cannot be seen or smelled, it has a much higher chance of escaping an attack.

Another defense mechanism possessed by many octopi is the ability to change color, much like a chameleon. Most animals get their skin color from chemicals in the skin called chromatophores (melanin is one of these chromatophores). Chromatophores might contain yellow, orange, red, brown, or black pigments, and the amount of each pigment present in the skin determines an animal’s color. While most animals are always the same color, some species of octopi can control the amount of each color pigment in their skin cells, allowing them to change color. Some poisonous octopi, when provoked, will change their skin to a bright, eye-catching color to warn predators that they are dangerous and ready to strike. Other octopi use this ability to change their skin to the color and texture of seaweed or coral, allowing them to blend in with their environment. Finally, some octopi—such as the mimic octopus—use this colorchanging ability to masquerade as another type of animal. The body of an octopus is highly flexible, and some species can combine this flexibility with their color-changing skills to make themselves resemble more dangerous animals such as sea snakes or eels.

Yet another defense mechanism possessed by some octopi is the ability to perform an autotomy, or self-amputation, of one of their limbs and regrow it later. Many species of skink and lizard also possess this ability, which allows them to shed their tails when caught by a predator and therefore get away. When a predator catches a tentacle the octopus can amputate this tentacle, thereby unfettering itself, and regrow the tentacle later. Some octopi, however, are even cleverer. When threatened by a predator, these octopi will shed a tentacle before being attacked in the hope that the predator will go after the detached tentacle rather than the octopus itself.

While the octopus may not be the most vicious creature in the ocean, its numerous and clever defense mechanisms help it to survive in the dangerous undersea world.

1374. Which of the following sentences from the passage best expresses the main idea?

	(a) The most well-known of the octopus’s defense mechanisms is its ability to squirt clouds of ink into the water
	(b) Some people say that the best defense is a good offense; an octopus, however, would disagree
	(c) Another defense mechanism possessed by many octopi is the ability to change color, much like a chameleon
	(d) When it wants to get away, the octopus has an impressive arsenal of tricks at its disposal

1375. The author claims in paragraph 1 that an octopus would disagree with the statement “the best defense is a good offense” because

	(a) octopi employ more defensive than offensive capabilities
	(b) octopi possess good defensive and offensive capabilities
	(c) octopi can protect themselves from teeth, horns, and claws
	(d) not all octopi possess the same defense mechanisms

1376. Which of the following statements best describes the organizational structure of paragraphs 2-4?

	(a) The author lays out several reasons to support the argument that the octopus has the best defense mechanisms of any sea creature
	(b) The author devotes one paragraph each to explaining three different defense mechanisms possessed by the octopus
	(c) The author devotes one paragraph each to highlighting three potential threats to the octopus and how the octopus deals with each one differently
	(d) The author compares and contrasts three different defense mechanisms employed by the octopus

1377. According to the passage, which of the following statements about the chemical melanin are true?

I. An octopus’s ink is composed primarily of melanin
II. Melanin is a chromatophore
III. Like the octopus, chameleons use melanin to change color

	(a) I only
	(b) I and II only
	(c) II and III only
	(d) I, II, and III

1378. As used in paragraph 4, which of the following is the best synonym for unfettering?

	(a) freeing
	(b) regrowing
	(c) amputating
	(d) sacrificing

1379. The final paragraph can best be described as a

	(a) prediction conclusion, in which the author looks toward the future
	(b) full circle conclusion, in which the author incorporates and builds on a word or theme from the introduction
	(c) solution conclusion, in which the author proposes a solution to a problem posed earlier in the passage
	(d) summary conclusion, in which the author restates the passage’s main idea

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Detailed Solution

1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
21	22	23	24	25	26	27	28	29	30	31	32	33	34	35	36	37	38	39	40
41	42	43	44	45	46	47	48	49	50	51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70	71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90	91	92	93	94	95	96	97	98	99	100
101	102	103	104	105	106	107	108	109	110	111	112	113	114	115	116	117	118	119	120
121	122	123	124	125	126	127	128	129	130	131	132	133	134	135	136	137	138	139	140
141	142	143	144	145	146	147	148	149	150	151	152	153	154	155	156	157	158	159	160
161	162	163	164	165	166	167	168	169	170	171	172	173	174	175	176	177	178	179	180
181	182	183	184	185	186	187	188	189	190	191	192	193	194	195	196	197	198	199	200
201	202	203	204	205	206	207	208	209	210	211	212	213	214	215	216	217	218	219	220
221	222	223	224	225	226	227	228	229	230	231	232	233	234	235	236	237	238	239	240
241	242	243	244	245	246	247	248	249	250	251	252	253	254	255	256	257	258	259	260
261	262	263	264	265	266	267	268	269	270	271	272	273	274	275	276	277	278	279	280
281	282	283	284	285	286	287	288	289	290	291	292	293	294	295	296	297	298	299	300
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361	362	363	364	365	366	367	368	369	370	371	372	373	374	375	376	377	378	379	380
381	382	383	384	385	386	387	388	389	390	391	392	393	394	395	396	397	398	399	400
401	402	403	404	405	406	407	408	409	410	411	412	413	414	415	416	417	418	419	420
421	422	423	424	425	426	427	428	429	430	431	432	433	434	435	436	437	438	439	440
441	442	443	444	445	446	447	448	449	450	451	452	453	454	455	456	457	458	459	460
461	462	463	464	465	466	467	468	469	470	471	472	473	474	475	476	477	478	479	480
481	482	483	484	485	486	487	488	489	490	491	492	433	494	495	496	497	498	499	500

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