The Fascinating World of Attine Ants
Read The Fascinating World of Attine Ants and check the IELTS Reading answers. Leaf-cutting ants and their fungus 'farm' are a marvel of nature and perhaps the best-known example of symbiosis the mutual dependence of two species. Ants cultivate a mushroom-like fungus in 'farms'. Both the ants and t…
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Leaf-cutting ants and their fungus 'farm' are a marvel of nature and perhaps the best-known example of symbiosis the mutual dependence of two species. Ants cultivate a mushroom-like fungus in 'farms'. Both the ants and their so-called 'agriculture' have been extensively studied over the years, but recent research has uncovered intriguing new findings. Ants invented agriculture 50 million years before people did, and the leaf-cutters, members of the large attine ant family, practise the most sophisticated example of it. They grow their fungus in underground chambers that can reach the size of a football. A single leaf-cutter nest may contain a thousand such chambers, embedded in an underground metropolis up to 18 feet deep, and support a society of more than a million ants.
Vocabulary from this passage
10 words worth learning before you sit the test, each with the sentence it appears in.
- alien organisms noun
Living things that are not native to a specific environment and may cause harm to the ecosystem
Currie discovered several alien organisms, including parasitic moulds, within the supposedly clean ant gardens.
- antibiotic resistance noun
The ability of bacteria to withstand the effects of an antibiotic that was once able to treat them
Ants use antibiotics so wisely that they avoid provoking antibiotic resistance in the target organisms.
- cultivate verb
To prepare and use land for crops or gardening; to grow or maintain a particular plant or organism
Leaf-cutter ants cultivate a specific type of mushroom-like fungus within their underground chambers.
- inhibit verb
To hinder, restrain, or prevent an action or process from occurring or developing further
The bacteria found on the ants' bodies produce toxins that inhibit the growth of deadly moulds.
- monoculture noun
The cultivation of a single crop in a given area to the exclusion of other species or varieties
Agricultural monocultures are often more vulnerable to parasites due to their lack of genetic diversity.
- propagate verb
To breed specimens of a plant or animal by natural processes from the parent stock or through cultivation
The specific fungus grown by the ants has been propagated for over twenty million years.
- relentless adjective
Oppressively constant; continuing without becoming less severe, intense, or slackening in strength or determination
Different varieties of fungus help the lower attine ants stay ahead of the relentless Escovopsis parasite.
- scrupulously adverb
In a very careful and thorough way; with great effort to avoid mistakes or neglect of detail
The worker ants scrupulously weed their gardens to ensure that no foreign organisms take root.
- sophisticated adjective
Highly developed and complex; reflecting a high degree of worldly knowledge or advanced technical refinement
Attine ants practice the most sophisticated form of agriculture found in the animal kingdom.
- symbiosis noun
Interaction between two different organisms living in close physical association, typically to the advantage of both species
The relationship between the ants and the fungus is a perfect example of biological symbiosis.
Answers with explanations
- 14. H
The text identifies two specific **feats beyond the power of humans**. These are the successful long-term cultivation of a **monocultural crop** (which humans struggle with due to parasites) and the use of **antibiotics** without triggering resistance. By contrasting these successes with human failures, the passage fulfills the requirement for 'two things' where ants have succeeded. Answer: H.
- 15. C
Paragraph C provides a direct **comparison** between leaf-cutters and **lower attines**. It specifies that lower attine **nests are smaller** and their farming **techniques more primitive** compared to the more sophisticated leaf-cutting ants. This explicit contrast in nest size and complexity matches the requirement for a comparison between the two groups' habitats. Answer: C.
- 16. B
This section provides an **assessment** of the leaf-cutters' environmental **impact** by quantifying their consumption of forest resources. Stating that **15 percent of leaf production** is consumed highlights the scale of their presence in the Neotropics. This numerical data specifically evaluates their ecological role. Answer: B.
- 17. F
The text describes the **effect** of the parasite **Escovopsis** on the colony. It explains that the disease **devastates** the food source, leading to the **starvation** of the ants. This cause-and-effect relationship between the parasite's bloom and the community's demise provides the requested information about its impact. Answer: F.
- 18. G
The passage explains the **advantage** of the lower attines' strategy. By growing **different varieties** of fungus, they maintain genetic diversity, which helps them **stay one step ahead** of the Escovopsis parasite. This reasoning provides the evolutionary logic behind why these ants do not use the monoculture approach of leaf-cutters. Answer: G.
- 19. D
The text details a 1994 DNA analysis that revealed the **discovery** of the **age** of the fungus. It explicitly mentions the timeframe of **23 million years**. This provides the specific chronological data requested regarding the history of attine-ant agriculture. Answer: D.
- 20. B
The passage distinguishes feeding habits, noting that **lower attines** use **fallen leaves** and **insect waste**. These materials constitute **dead vegetation**, as opposed to the fresh vegetation used by leaf-cutters. Therefore, this feature is unique to the lower attine group. Answer: B.
- 21. A
The text describes specialized roles for **leaf-cutter worker ants**. It specifically mentions **miniature workers** whose job is to **clean off alien growths**, which corresponds to keeping the fungus free of foreign organisms. This made-to-fit size hierarchy is a characteristic of the leaf-cutting group. Answer: A.
- 22. A
Paragraph B states that **leaf-cutters** are able to consume leaves **laden with poisonous chemicals** because their fungus digests the toxins. This **ability to safely eat** harmful plants via their symbiotic 'mushroom' is a highlighted achievement of the leaf-cutters. Answer: A.
- 23. A
The DNA analysis reveals that **leaf-cutters** cultivate a **single pure strain** of fungus, referred to as a **monoculture**. In contrast, lower attines are described as having multiple varieties from different groups. Thus, cultivating a single strain is a defining feature of leaf-cutters. Answer: A.
- 24. A
The text describes the **leaf-cutter nest** as an 'underground metropolis' containing **a thousand chambers**. These chambers are used for **growing fungus** and can be as large as a football. This scale of construction is explicitly linked to the leaf-cutter species. Answer: A.
- 25. B
The writer notes that **earlier studies** over a 'century of ant research' **did not support** Currie's theory because they found no evidence of parasites. The claim that no previous work was done is wrong because research existed; it just disagreed with him. The idea that textbooks lacked detail or his theory was proven wrong is contradicted by his eventual discovery. Answer: B.
- 26. D
Currie used a **microscope** to find a **bacterium** on the ant's body. The text notes this bacterium is highly **useful to humans** as it is the source of **half the antibiotics** in medicine. The options about a white covering or wax were previous (incorrect) beliefs, and the text never suggests the substance is poisonous to humans. Answer: D.