Sources Of Rubber - IELTS Listening Answers & Explanations
From Cambridge IELTS 21 Academic Listening Test 1 · Part 4 · Questions 31–40
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Questions
Questions 31–40 Note Completion
Complete the notes below.
Write ONE WORD ONLY for each answer.
Sources of rubber
Three resources which are essential for industrial civilisation
- 31
- fossil fuels
- rubber
Natural rubber
This mainly comes from the Pará rubber tree, now cultivated in South-East Asia. The supply is limited because
- the growth of the tree is 32 .
- production cannot easily be adjusted because of increasing or decreasing 33 .
- the tree only grows near the 34 .
- extracting the latex (rubber) is labour-intensive
- it is very difficult to 35 rubber after production.
New threats include
- lack of genetic diversity, leading to danger of disease caused by a 36 .
- a shift to the cultivation of palm oil
- extreme 37 events.
Synthetic rubber
- may be used for engine parts and cooking utensils
- is less 38 than natural rubber
- is unsuitable for many purposes e.g. the tyres of aircraft.
An alternative source of natural rubber
- A wild flower (a type of dandelion) has rubber in its 39 .
- It can be grown in many locations and does not require good 40 .
Answers & Explanations Summary
| # | Answer | Evidence | Explanation |
|---|---|---|---|
| Q31 | metals / metal | There are three types of natural resource without which industry could not exist. One of these is metal - without that we'd have no machines and no transportation. Another is fossil fuels, which we need to power those machines. But there's a third resource that's essential to connect the different parts of a machine together with belts and pipes and shock absorbers, and that is rubber | Excerpt/Transcript Explanation: The transcript says there are three natural resources needed for industry. It lists metal first, followed by fossil fuels and rubber. Answer Explanation: The answer means hard materials like iron or steel that are used for building machines and vehicles. Reason For Correctness: The correct answer is metal because the speaker lists three specific natural resources that an industrial society must have to function. These three essential materials are metal, fossil fuels, and rubber. In the notes, fossil fuels and rubber are already written, so metal is the missing item needed to complete the list of three. |
| Q32 | slow | It can take eight to ten years for a tree to start producing rubber, so cultivating them's a slow process | Excerpt/Transcript Explanation: The transcript explains that since it takes many years for a tree to be ready to make rubber, the process of growing them is slow. Answer Explanation: The answer means that the Pará rubber tree takes a very long time to grow and become useful. Reason For Correctness: The correct answer is correct because the speaker explains that rubber trees do not grow quickly. It takes a long time—eight to ten years—before a tree is ready to produce rubber. Therefore, the speaker describes the act of growing (cultivating) these trees as a 'slow' process. |
| Q33 | demand | With most crops, farmers don't have to think very far ahead, so they can easily change what crop they produce, or how much of a crop they produce, if they find the demand for that crop is rising or falling | Excerpt/Transcript Explanation: The transcript explains that for most plants, a farmer can easily choose to grow more or less depending on whether the desire (demand) for that item is going up or going down. Answer Explanation: The answer "demand" refers to the amount of interest or desire people have to buy a specific product. Reason For Correctness: The correct answer is "demand" because the speaker identifies a challenge in the rubber industry: farmers find it difficult to change their production levels in response to how many people want to buy the product. Unlike other crops where farmers can quickly increase or decrease supply when the need (demand) changes, rubber trees take up to ten years to grow, making it hard to adjust production when the market's need for rubber goes up or down. |
| Q34 | equator | The result is that it can't be grown in the northern or southern parts of the globe, only around the equator | Excerpt/Transcript Explanation: The transcript says that rubber trees do not grow in cold or far-away places; instead, they only grow in the hot area in the center of the world. Answer Explanation: The answer is the name of the imaginary line around the middle of the Earth where the weather is usually very hot. Reason For Correctness: The correct answer is 'equator' because the transcript explains that rubber trees are very specific about where they can live. They need specific temperatures and rain that are only found in the middle part of the world. Because they cannot grow in the north or south, their growth is limited to the area around this specific middle line. |
| Q35 | recycle | With other resources such as water and glass, when we've finished using them we can recycle them, but although this is also possible with rubber, it's very difficult, so that also reduces the amount we have available | Excerpt/Transcript Explanation: The transcript explains that it is very hard to reuse rubber after we are done with it, unlike water or glass. Because it is so hard to process used rubber, the total amount of rubber we have to use is limited. Answer Explanation: The answer "recycle" means to take something that has already been used and process it so that it can be used again instead of being thrown away. Reason For Correctness: The correct answer is "recycle" because the speaker discusses how some materials can be easily reused, but rubber is not one of them. The speaker mentions that while we can reuse things like water and glass, doing the same with rubber is very hard (difficult). This difficulty in reusing old rubber helps explain why there is not enough natural rubber to meet the world's needs. |
| Q36 | fungus | The most dangerous threat is a fungus, which destroyed large numbers of rubber trees in Brazil, and which could cause devastation to plantations worldwide | Excerpt/Transcript Explanation: The transcript states that a fungus is the most serious danger. This fungus already killed many rubber trees in Brazil and has the power to destroy many more farms around the world. Answer Explanation: The answer 'fungus' is a type of living thing (like mold or a mushroom) that can cause diseases in plants. Reason For Correctness: The correct answer is 'fungus' because the transcript identifies it as the biggest danger to rubber trees. Since the trees in South-East Asia are very similar to each other, they can all easily get sick or be destroyed by this specific type of organism. |
| Q37 | weather | And finally, in recent years South-East Asia, like other parts of the world, has been repeatedly hit by extreme types of weather, and this looks likely to continue in the future | Excerpt/Transcript Explanation: The transcript explains that lately, Southeast Asia and other places have had many very strong or bad weather events, which is a new problem for getting rubber. Answer Explanation: The answer is the word for the state of the air outside, such as rain, sun, or wind. Reason For Correctness: The correct answer is 'weather' because the speaker lists it as one of the recent problems for the supply of natural rubber. The transcript mentions that some parts of the world have been experiencing 'extreme types of weather,' which acts as a threat to rubber production. These unusual or strong weather events create difficulties for farming and supply. |
| Q38 | strong | But compared with natural rubber, it's not anything like as strong, and this means it can't replace natural rubber in other products | Excerpt/Transcript Explanation: The transcript explains that while synthetic rubber looks and acts like rubber, it is much weaker than natural rubber. Because it lacks strength, it cannot be used for every product. Answer Explanation: The answer "strong" means having the power to handle heavy weight or pressure without breaking or tearing. Reason For Correctness: The correct answer is "strong" because the transcript compares man-made (synthetic) rubber to rubber that comes from trees (natural rubber). It explains that synthetic rubber is "not anything like as strong." In this context, "not anything like as" is a way to say "much less," so synthetic rubber is much less strong than natural rubber. This makes it unsuitable for things that need to be very tough, like tires for planes. |
| Q39 | roots | But when it's pulled up and its roots cut open, they're found to contain rubber | Excerpt/Transcript Explanation: The transcript explains that after pulling the dandelion plant out of the soil and cutting into the underground parts, you can find the rubber inside. Answer Explanation: The answer "roots" refers to the part of the dandelion plant located underground where rubber can be found. Reason For Correctness: The correct answer is "roots" because the speaker discusses dandelions as an alternative source of natural rubber. The transcript specifically mentions that rubber is found when the roots of these plants are cut open. This indicates that the rubber is stored within that specific part of the plant. |
| Q40 | soil | They'll grow in all sorts of places, and they don't need rich soil | Excerpt/Transcript Explanation: The transcript says that these specific plants can live in various environments and do not require high-quality dirt to grow successfully. Answer Explanation: The answer 'soil' refers to the top layer of earth or dirt where plants grow. Reason For Correctness: The correct answer is 'soil' because the text explains that dandelions are very adaptable. Unlike some other plants that need specific conditions, dandelions can grow in many places and do not need 'rich soil' (which is another way of saying 'good soil') to survive. |
Transcript
Much of the world now lives in an industrial civilisation. But this has only become possible because we have the necessary natural resources. There are three types of natural resource without which industry could not exist. One of these is metal - without that we'd have no machines and no transportation. Another is fossil fuels, which we need to power those machines. But there's a third resource that's essential to connect the different parts of a machine together with belts and pipes and shock absorbers, and that is rubber. It's now used in over 40,000 products, from waterproof footwear to surgical gloves.
At present, we have two types of rubber in common use. One is natural rubber, which nearly all comes from the Pará rubber tree. This was originally native to Brazil, but is now cultivated on plantations in South-East Asia. Recently, however, concern's been growing that supplies may soon be insufficient for the world's needs. So what exactly is limiting the supply of natural rubber?
Well, for one thing, rubber trees don't just spring up overnight. It can take eight to ten years for a tree to start producing rubber, so cultivating them's a slow process. And this leads to another problem. With most crops, farmers don't have to think very far ahead, so they can easily change what crop they produce, or how much of a crop they produce, if they find the demand for that crop is rising or falling. But if you have to plant eight or ten years ahead, that's much harder. And also the rubber tree's very choosy about where it grows. It needs the right temperature, the right amount of rainfall, and the right altitude - not too high and not too low. The result is that it can't be grown in the northern or southern parts of the globe, only around the equator. Another problem is that the rubber is basically extracted in the same way as it's been done for hundreds of years, and that's by hand, by making small cuts in the trunk of the tree, and putting a little cup there to catch the latex, as the rubber is called. It's very labour-intensive. And it's not just the initial production that's limiting supplies. With other resources such as water and glass, when we've finished using them we can recycle them, but although this is also possible with rubber, it's very difficult, so that also reduces the amount we have available.
And in the last few years, there have been new threats to the supply of natural rubber. One problem is linked to the fact that nearly all the rubber trees in South-East Asia are descended from just a small number of seeds brought from Brazil in the nineteenth century. This means that there's very little genetic diversity among the trees, which in turn makes them very vulnerable to disease. The most dangerous threat is a fungus, which destroyed large numbers of rubber trees in Brazil, and which could cause devastation to plantations worldwide. Another problem is that farmers in South-East Asia are increasingly turning to the cultivation of palm oil, which is easier and more profitable for them. And finally, in recent years South-East Asia, like other parts of the world, has been repeatedly hit by extreme types of weather, and this looks likely to continue in the future.
However, as well as using natural rubber, it's also possible to make rubber synthetically. This works very well for some purposes, for example, making engine parts, or silicone pots and pans used for cooking. But compared with natural rubber, it's not anything like as strong, and this means it can't replace natural rubber in other products. For example, while a mixture of natural rubber and synthetic rubber works well in car tyres, only natural rubber can stand up to the extreme speeds of aircraft tyres during take-off and landing.
So for some time, scientists have been looking for alternative sources of natural rubber. One that's been known about for some time seems initially to be a rather unlikely source. It's a wild plant with yellow flowers that we normally regard as a weed when we see it in our gardens. But when it's pulled up and its roots cut open, they're found to contain rubber.
Now, compared to the rubber tree, dandelions produce relatively small amounts of rubber, but unlike rubber trees, they're very adaptable. They'll grow in all sorts of places, and they don't need rich soil. So at present there are several projects underway investigating the possibility of using dandelions as a source of rubber.
Another possibility is a desert shrub grown in Mexico and Texas ...