Answers and Explanations—5.6 Habitat Fragmentation

P1	Paragraph 1	Comments
S1	The habitats of terrestrial animals, which provide food, shelter, and places to bear and raise offspring, have been changing at an unnatural pace in recent centuries.	Habitats have been changing.
2	The restriction of a once large, continuous habitat into smaller, segmented pieces is called habitat fragmentation.	Habitat fragmentation = restriction into smaller segments.
3	This process occurs over all types of habitats and is widely recognized as one of the major barriers to effective conservation efforts.	This is a barrier to effective conservation.

	According to paragraph 1, what is true of habitat fragmentation?	Fact. S2 defines habitat fragmentation. S3 provides additional information about the phenomenon.
✗	A It provides food and shelter to terrestrial animals.	S1 says this about habitats, not habitat fragmentation.
✓	B It is a barrier to conservation efforts.	Correct. S3: “This process… is widely recognized as one of the major barriers to effective conservation efforts.”
✗	C It occurs only in specific types of habitats.	Opposite. S3: “This process occurs over all types of habitats.”
✗	D It was widely recognized in recent centuries.	This mixes up language from S3 (“widely recognized”) and S1 (“in recent centuries”). The mash-up isn’t necessarily true.

P2	Paragraph 2	Comments
S1	Habitat fragmentation occurs when the landscape is changed so that plants and animals no longer have access to all of the same areas they once did.	Habitat fragmentation occurs when landscape changes so there’s no more access.
2	In some cases, this process can occur because part of the habitat has been destroyed, leaving animals with less roaming space than they previously had.	Some cases: part of habitat is destroyed.
3	In other cases, the habitat still exists, but a barrier emerges that prevents animals from reaching all areas of their former habitat.	Other cases: barrier emerges.
4	Regardless of how it occurs, habitat fragmentation can be dangerous to both plants and animals.	Dangerous to both plants and animals.
5	Plants are unable to respond quickly to change, so if they rely on an aspect of their habitat that no longer exists, there is often not enough time to adapt, and the plant will die off.	Explains how.
6	Animals are more commonly able to move into the smaller habitat areas, but they suffer nonetheless.
7	They may be cut off from food or shelter.
8	Often, the resources remaining can support only a smaller population, leaving the animals vulnerable to disease.

	The words “an aspect” in the passage are closest in meaning to	VOCABULARY. “Aspect” = feature, characteristic, property or quality.
✗	A a food source	A food source is an example of what an aspect could be, but it’s too narrow a replacement. Many more kinds of things could be aspects of a habitat (e.g., its average temperature or its elevation above sea level).
✗	B an advance	Again, this is too specific. An “advance” of a habitat would mean its physical progression into neighboring areas. A possible aspect of a habitat could be that it is advancing, but that possibility excludes all other potential aspects.
✓	C an attribute	Correct. “They rely on an aspect of their habitat” = they depend on some attribute, feature, or characteristic of their habitat.
✗	D another species	Again, this is too specific.

	According to paragraph 2, which of the following occurs more with plants that suffer habitat fragmentation than with animals that suffer habitat fragmentation?	Fact. S5 discusses the impact on plants. S6–8 discuss the impact on animals.
✓	A Plants cannot shift as easily into smaller areas.	Correct. S6: “Animals are more commonly able to move into the smaller habitat areas.” The comparison “more” comes after S5, which describes plant behavior. So the comparison is to plants, which are therefore less able to shift or move into those areas.
✗	B Plants are more vulnerable to disease.	S8 mentions only that animals in smaller populations are vulnerable to disease.
✗	C Plants respond more quickly to change.	Opposite, if anything. S5: “Plants are unable to respond quickly to change.”
✗	D Plants have less time to adapt to the absence of resources.	Not supported. S5 mentions that plants often do not have enough time to adapt when a necessary aspect of their habitat disappears. But that doesn’t mean plants have less time than animals do to adapt.

	According to paragraph 2, a cause of habitat fragmentation is	Fact. S1–3 outline causes of habitat fragmentation. S1 explains the general cause: the landscape changes in such a way as to limit access by plants and animals. The change could be destruction of part of the habitat (S2) or the emergence of a barrier (S3).
✗	A the lack of access by plants and animals to previously available areas	This is the result of habitat fragmentation, not the cause of it. In fact, this result is what defines the change in a landscape as habitat fragmentation, according to S1.
✓	B the creation of physical obstacles within the habitat	Correct. S3: “a barrier emerges.” The phrase “the creation of physical obstacles” means the same thing.
✗	C the expansion of a habitat to increase access	This would be the opposite of habitat fragmentation.
✗	D the inability to adapt rapidly to changes in the landscape	S5 mentions that this inability to adapt quickly is a property of plants. It is not a cause of habitat fragmentation.

P3	Paragraph 3	Comments
S1	While habitat fragmentation can be devastating to populations, it naturally occurs over time.	Habitat fragmentation occurs naturally.
2	Mountains will rise, volcanoes will erupt, and rivers will change course.
3	Any of these changes and countless other natural progressions will segment large areas into smaller ones.
4	It is widely accepted, however, that the primary source of habitat fragmentation in the modern world is human activity.	But human activity is now the primary source.
5	As humans expand into new areas, they change the environment to suit their needs.	Why and how.
6	Habitats are destroyed to make way for man-made buildings and are divided to connect those buildings.
7	Plants and animals that encroach into areas where humans live are repelled or killed.
8	Edge species, which live on the borders of habitats, expand as more borders are created and will compete with species that cannot live on edges.
9	The increased competition in a decreased space endangers many species.

	The word “source” in the passage is closest in meaning to	VOCABULARY. “Source” = cause, reason, the place where something comes from.
✗	A objective	“Objective” = goal, purpose, object, result.
✗	B function	“Function” = purpose, role, way in which something operates.
✓	C cause	Correct. S4: “the primary source of habitat fragmentation… is human activity” = the main cause of habitat fragmentation, or the biggest reason for it, is human activity.
✗	D center	Not exactly. A center of some phenomenon doesn’t have to be its source or cause. A center is just where it happens a lot.

	According to paragraph 3, what currently has the greatest influence on habitat fragmentation?	Fact. S4 describes “the primary source of habitat fragmentation.”
✓	A The actions of human beings	Correct. S4: “the primary source of habitat fragmentation… is human activity.”
✗	B Natural forces such as volcanic eruptions	S2 mentions volcanic eruptions as an example of a natural cause of habitat fragmentation. But they are not described as having the greatest influence.
✗	C Encroachment by plants and animals	Described in S7 as an effect of habitat fragmentation caused by humans.
✗	D Increased competition at habitat borders	Described in S8–9 as an effect of habitat fragmentation caused by humans.

	The word “endangers” in the passage is closest in meaning to	VOCABULARY. “Endangers” = threatens, puts in danger or at risk.
✗	A includes	Unrelated. “Includes” = contains.
✗	B empowers	Opposite. “Empowers” = makes stronger or more confident.
✗	C deters	Unrelated. “Deter” = to discourage or instill doubt or fear of consequences.
✓	D jeopardizes	Correct. “The increased competition… endangers many species” = this competition jeopardizes, or puts in danger, many species.

P4	Paragraph 4	Comments
S1	Four specific activities or structures are known as the most common causes of man-made habitat fragmentation: roads, housing developments, agriculture, and logging.	Habitat fragmentation by humans has 4 common causes.
2	Roads require an extensive expanse of land to be cleared, including the area surrounding the road.	Explains one cause (roads).
3	A single road will split a large habitat into two smaller ones and increase the edge area.
4	Animals that attempt to traverse the road to reach land that may be essential for their survival are in additional danger from fast-moving cars.

	Why does the author mention “roads,” “housing developments,” “agriculture,” and “logging”?	Purpose. S1 lists these “four specific activities or structures.”
✗	A To give examples of processes that can slow habitat fragmentation	Opposite. These are all specific causes of habitat fragmentation.
✗	B To explain why habitat fragmentation is so dangerous	The paragraph does mention the danger to animals attempting to cross roads, but this is not the primary reason the list of four items is given.
✗	C To list four specific activities or structures that are known to be man-made	In fact, the four items do form a list of specific human activities or man-made structures. But the reason for this list is omitted. The purpose is not just to list four human activities or structures, but to assert that these are the most common causes of habitat fragmentation.
✓	D To illustrate the ways that human activity most impacts habitat fragmentation	Correct. S1 notes that these activities or structures are the “most common causes of man-made habitat fragmentation.”

P5	Paragraph 5	Comments
S1	Housing developments are necessary, as the population of humans continues to grow.	Explains other 3 causes (housing, agriculture, & logging)
2	Such development not only forces land to be cleared, but also creates competition between humans and edge species.
3	Animal and pest control keep many native species from coming into housing developments.
4	Non-native species, particularly plants, are regularly introduced into housing developments for the benefit of the occupants.
5	Population growth also leads to the need for more agriculture.
6	Consequently, large tracts of land are bulldozed and the natural plants destroyed to make way for crops.
7	The cleared land has lost all its utility to the plants and animals that once called that area home.
8	Finally, logging, whether for industrial uses or for firewood, destroys large trees that may be necessary for species’ survival.
9	Removing trees shrinks the habitat and could eliminate both food and shelter.
10	At the same time, the presence of humans, their equipment, and the roads they need can imperil plants and animals in the area.

	The word “utility” in the passage is closest in meaning to	VOCABULARY. “Utility” = usefulness, use, value.
✓	A value	Correct. “The cleared land has lost all its utility to the plants and animals” = the cleared land has lost all its value to these species.
✗	B nutrients	Too specific. Nutrients can be a form of utility or value, but “utility” is a much broader term.
✗	C stability	Again, too specific. Stability can be a form of utility or value, but “utility” is a much broader term.
✗	D energy	Again, too specific. Not all forms of utility or value can be called energy.

	Why does the author mention “firewood”?	Purpose. S8: “logging, whether for industrial uses or for firewood, destroys large trees.” The two phrases “for industrial uses” and “for firewood” describe reasons for logging. “Whether… or” indicates that the particular reason doesn’t matter, with regard to the effect logging has on habitat fragmentation.
✗	A To emphasize the danger of fires to habitats	Not mentioned here.
✗	B To clarify that human activity is not always undesirable	The author does not pass judgment on human activity, declaring any of it undesirable or desirable. Rather, the author is explaining the effects of that activity.
✓	C To provide an example of why logging may occur	Correct. S8: “for firewood” is an example of a reason for logging.
✗	D To point out an easily eliminated cause of habitat fragmentation	The passage never states that cutting firewood is easily eliminated as a cause of habitat fragmentation.

P6	Paragraph 6	Comments
S1	For a thriving and robust species, ample area, reasonable competition, and access to essentials are all necessary.	Ample habitats are necessary for species to thrive.
2	If habitat fragmentation continues at the current pace, species will be restricted to areas in which only small populations can survive or will lose the ability to survive entirely.	If habitat fragmentation continues, species will shrink in numbers or vanish.
3	Conserving large tracts of land in a variety of areas is already underway and may help to slow this process.	Conserving large tracts may help slow habitat fragmentation.

	Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 6? Incorrect choices change the meaning in important ways or leave out essential information.	Simplify Sentence. S2 is a conditional prediction: if habitat fragmentation continues at the current rate, Y or Z will happen. Namely, species will shrink in numbers (by being restricted to areas that can only support small populations) or die off altogether.
✗	A Species will be eliminated or restricted to areas that can only support small populations if the current pace of habitat fragmentation continues to slow.	Opposite. This choice would be fine if the last part of the sentence were “if the pace of habitat fragmentation does not slow.”
✗	B Habitat fragmentation, if not slowed, will be restricted to areas in which only small populations of species can survive, if at all.	It’s not the habitat fragmentation that will be restricted to certain areas, but the species themselves.
✓	C The current pace of habitat fragmentation, if continued, will eradicate species or restrict them to small numbers in their remaining habitats.	Correct. “The current pace of habitat fragmentation, if continued, will eradicate species” is equivalent to the original phrasing: “species… will lose the ability to survive entirely” (if the current pace is continued). The rest of the rephrased sentence captures the original meaning.
✗	D Only small populations of species, or none at all, will survive in areas currently restricted from the continued pace of habitat fragmentation.	Also somewhat opposite. “Restricted from” would mean that the areas would not be subject to continued habitat fragmentation. You would expect species to do better in areas without habitat fragmentation.

	It can be inferred from paragraph 6 that compared with fragmented habitats, habitats that have not been fragmented	Inference. P6 (as well as preceding paragraphs) discuss the damaging effects of fragmented habitats. Specifically, S2 mentions the effects of continued habitat fragmentation: species will be eliminated or restricted to areas that can only support small populations. You can make inferences about unfragmented habitats by comparison.
✗	A are likely to be much rarer globally	Notice that you are asked to compare unfragmented habitats with fragmented habitats. You aren’t told anything about their comparative size or numbers geographically. Unfragmented habitats are likely to become rarer over time, but that could be starting from a high proportion.
✗	B have probably benefited from conservation efforts	S3 remarks on conservation efforts, indicating that large tracts of land are being conserved now. But you can’t conclude that unfragmented habitats worldwide have all or mostly benefited from these conservation efforts.
✗	C provide access to all the essentials species need	Extreme. You could say that unfragmented habitats are more likely to provide species with access to at least some essentials. But you can’t infer that these habitats actually provide access to all the essentials.
✓	D will likely support larger populations	Correct. S1 discusses the “ample area, reasonable competition, and access to essentials” that are necessary for “thriving and robust species.” It can be inferred that these features apply to habitats that have not been fragmented.

P5	Paragraph 5	Comments
S1–2	Housing developments are necessary, as the population of humans continues to grow. Such development not only forces land to be cleared, but also creates competition between humans and edge species.
3–4	A Animal and pest control keep many native species from coming into housing developments. Non-native species, particularly plants, are regularly introduced into housing developments for the benefit of the occupants.	“Edge species” in S2 are not clearly non-native plants.
5–6	B Population growth also leads to the need for more agriculture. Consequently, large tracts of land are bulldozed and the natural plants destroyed to make way for crops.	Correct. S4 mentions “non-native species, particularly plants” that are brought into housing developments. The inserted sentence appropriately refers back to these non-native plants.
7–8	C The cleared land has lost all its utility to the plants and animals that once called that area home. Finally, logging, whether for industrial uses or firewood, destroys large trees that may be necessary for species’ survival.	“Natural plants” in S6 would be native plants, not non-native ones.
9–10	D Removing trees shrinks the habitat and could eliminate both food and shelter. At the same time, the presence of humans, their equipment, and the roads they need can imperil plants and animals in the area.	“Large trees” in S8 are not non-native plants.

	These species compete with native plants and often exacerbate habitat fragmentation. Where would the sentence best fit?	Insert Text. “These species” needs to refer properly to species mentioned in the previous sentence. According to the inserted sentence, these species “compete with native plants.” So these species should not be native plants, but they should still be plants (in order to compete with them). You are looking for non-native plants or a synonymous expression in the prior sentence.
✗	A Choice A
✓	B Choice B	Correct.
✗	C Choice C
✗	D Choice D

	Whole Passage	Comments
P1	The habitats of terrestrial animals, which provide food, shelter, and places to bear and raise offspring…	Habitats have been changing. Habitat fragmentation = restriction into smaller segments. This is a barrier to effective conservation.
P2	Habitat fragmentation occurs when the landscape is changed so that plants and animals no longer have access…	Habitat fragmentation occurs when landscape changes so there’s no more access. Some cases: part of habitat is destroyed. Other cases: barrier emerges. Dangerous to both plants and animals. Explains how.
P3	While habitat fragmentation can be devastating to populations, it naturally occurs over time…	Habitat fragmentation occurs naturally. But human activity is now the primary source. Why and how.
P4	Four specific activities or structures are known as the most common causes of man-made habitat fragmentation…	Habitat fragmentation by humans has 4 common causes. Explains one cause (roads).
P5	Housing developments are necessary, as the population of humans continues to grow…	Explains other 3 causes (housing, agriculture, & logging).
P6	For a thriving and robust species, ample area, reasonable competition, and access to essentials are all necessary…	Ample habitats are necessary for species to thrive. If habitat fragmentation continues, species will shrink in numbers or vanish. Conserving large tracts may help slow habitat fragmentation.

	Habitat fragmentation is a process that poses a threat to the survival of some plant and animal species.	Summary. Correct answers must be clearly expressed in the passage. They must also be among the major points of the passage. They should tie as directly as possible to the summary given.
✗	a Habitat fragmentation can occur when part of the habitat is destroyed by the changed course of a river.	True but minor detail. P3 S2 mentions that “rivers will change course,” but this is just a quick example of how nature can cause habitat fragmentation. Moreover, the focus of the passage is on habitat fragmentation caused by humans.
✓	b Despite the fact that habitat fragmentation occurs naturally, human activity is currently its principal cause.	Correct. This is the main point of P3.
✗	c Creation of roads is the most common human activity that results in habitat fragmentation.	Roads are listed as the first of the four specific causes of human-generated habitat fragmentation. But nothing in the passage tells you that this is the most common of the four causes.
✓	d The four major contributors to man-made habitat fragmentation impact species in various powerful ways.	Correct. P4–5 describe these four causes in detail.
✗	e Conservation efforts will be able to halt habitat fragmentation if implemented worldwide.	Extreme. The last sentence of P6 gives some hope by mentioning conservation efforts. But the sentence only claims that these efforts “may help to slow” habitat fragmentation, not halt or stop it altogether.
✓	f Without limiting the human impact on large areas of land, many species will shrink and possibly disappear over time.	Correct. P6 S2 delivers this final, culminating thought as a clear warning about the future.