Pheidole dentata, a native ant of the south-eastern U.S., isn’t immortal. But scientists have found that it doesn’t seem to show any signs of aging. Old worker ants can do everything just as well as the youngsters, and their brains appear just as sharp. ‘We get a picture that these ants really don’t decline,’ says Ysabel Giraldo, who studies the ants for her doctoral thesis at Boston University.
Such age-defying feats are rare in the animal kingdom. Naked mole rats can live for almost 30 years and stay fit for nearly their entire lives. They can still reproduce even when old, and they never get cancer. But the vast majority of animals deteriorate with age just like people do. Like the naked mole rat, ants are social creatures that usually live in highly organised colonies. ‘It’s this social complexity that makes P. dentata useful for studying aging in people,’ says Giraldo, now at the California Institute of Technology. Humans are also highly social, a trait that has been connected to healthier aging. By contrast, most animal studies of aging use mice, worms or fruit flies, which all lead much more isolated lives.
In the lab, P. dentata worker ants typically live for around 140 days. Giraldo focused on ants at four age ranges: 20 to 22 days, 45 to 47 days, 95 to 97 days and 120 to 122 days. Unlike all previous studies, which only estimated how old the ants were, her work tracked the ants from the time the pupae became adults, so she knew their exact ages. Then she put them through a range of tests.
Giraldo watched how well the ants took care of the young of the colony,…
Questions 1–8
Complete the notes below. Choose ONE WORD ONLY from the passage for each answer.
ONE WORD ONLY
1.Focused on a total of ___ different age groups of ants, analyzing
In my view, it is perfectly possible for many species of animals living in zoos or wildlife parks to have a quality of life as high as, or higher than, in the wild. Animals in good zoos get a varied and high-quality diet with all the supplements required, and any illnesses they might have will be treated. Their movement might be somewhat restricted, but they have a safe environment in which to live, and they are spared bullying and social ostracism by others of their kind. They do not suffer from the threat or stress of predators, or the irritation and pain of parasites or injuries. The average captive animal will have a greater life expectancy compared with its wild counterpart, and will not die of drought, of starvation or in the jaws of a predator. A lot of very nasty things happen to truly ‘wild’ animals that simply don’t happen in good zoos, and to view a life that is ‘free’ as one that is automatically ‘good’ is, I think, an error. Furthermore, zoos serve several key purposes.
Firstly, zoos aid conservation. Colossal numbers of species are becoming extinct across the world, and many more are increasingly threatened and therefore risk extinction. Moreover, some of these collapses have been sudden, dramatic and unexpected, or were simply discovered very late in the day. A species protected in captivity can be bred up to provide a reservoir population against a population crash or extinction in the wild. A good number of species only exist in captivity, with many of these living in zoos. Still more only exist in the wild because they have been reintroduced from zoos, or…
Questions 14–17
The Reading Passage has six paragraphs, A-F. Which paragraph contains the following information?
14.a reference to how quickly animal species can die out
Chelsea Rochman, an ecologist at the University of California, Davis, has been trying to answer a dismal question: Is everything terrible, or are things just very, very bad?
Rochman is a member of the National Center for Ecological Analysis and Synthesis’s marine-debris working group, a collection of scientists who study, among other things, the growing problem of marine debris, also known as ocean trash. Plenty of studies have sounded alarm bells about the state of marine debris; in a recent paper published in the journal Ecology, Rochman and her colleagues set out to determine how many of those perceived risks are real.
Often, Rochman says, scientists will end a paper by speculating about the broader impacts of what they’ve found. For example, a study could show that certain seabirds eat plastic bags, and go on to warn that whole bird populations are at risk of dying out. ‘But the truth was that nobody had yet tested those perceived threats,’ Rochman says. ‘There wasn’t a lot of information.’
Rochman and her colleagues examined more than a hundred papers on the impacts of marine debris that were published through 2013. Within each paper, they asked what threats scientists had studied – 366 perceived threats in all – and what they’d actually found.
In 83 percent of cases, the perceived dangers of ocean trash were proven true. In the remaining cases, the working group found the studies had weaknesses in design and content which affected the validity of their conclusions – they lacked a control group, for example, or used faulty statistics.
Strikingly, Rochman says,…
Questions 27–33
Do the following statements agree with the information given in the Reading Passage?
27.Rochman and her colleagues were the first people to research the problem of marine debris.
Check your work
Answers & explanations
Every answer is available. The first 3 explanations are free; PrepGo Premium unlocks the rest.
40 answers3 explanations open
1
four / 4
The correct answer matches the information given in the passage, which stated that the research focused on ants at four distinct age ranges. Therefore, 'four' is the appropriate answer in this context.
2
young
The correct answer is 'young' because the excerpt specifically mentions Ysabel Giraldo watching how well the ants took care of the young in the colony, indicating a focus on the young age group of ants in her research.
3
food
The correct answer is 'food' because the excerpt mentions the ants looking for food by following a scent trail, indicating that food is an essential element being analyzed in Ysabel Giraldo's research related to the behavior of ants.
4
light
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5
aggressively
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6
location
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7
neurons
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8
chemicals
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9
FALSE
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10
TRUE
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11
FALSE
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12
NOT GIVEN
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13
TRUE
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14
B
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15
E
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16
C
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17
A
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18
TRUE
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19
TRUE
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20
NOT GIVEN
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21
FALSE
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22
NOT GIVEN
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23
B
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24
D
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25
B
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26
E
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27
FALSE
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28
NOT GIVEN
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29
FALSE
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30
TRUE
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31
FALSE
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32
TRUE
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33
NOT GIVEN
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34
large
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35
microplastic
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36
populations
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37
concentrations
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38
predators
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39
disasters
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40
A
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Understand why, not only what.
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