Sources of rubber: listening answers and explanations
A lecturer explains why rubber is one of three resources industry can't do without. She looks at why the supply of natural rubber is limited, new threats to it, the weaknesses of synthetic rubber, and the dandelion as an alternative source.
One ten-gap note block in strict order. The headings match the talk: three resources, limits on natural rubber ('So what exactly is limiting the supply'), new threats ('in the last few years'), synthetic rubber ('it's also possible to make rubber synthetically'), then the dandelion.
Answer key and self-check
Type what you wrote and hit mark. Hide the key first if you haven't done the part yet. Every question number jumps to its explanation.
How to attack this block: One word only, so check the grammar around each gap: an adjective after 'is', a noun after 'a', a verb after 'to'. The notes paraphrase heavily ('only grows near the' for 'only around the equator'), so listen for the idea, then write the exact word you hear.
Question 31
Answer: metalVery start of the talk, after 'three types of natural resource'
Also accepted: metals
What is the first of the three resources industry depends on?
One of these is metal - without that we'd have no machines and no transportation.
Question says → You hear
Three resources which are essentialthree types of natural resource without which industry could not exist
Why: The notes list fossil fuels and rubber, so the missing one is the first she names: metal. Metals is also accepted.
The trap: Machines and transportation are what metal makes possible, not the resource itself.
Question 32
Answer: slowFirst point after 'So what exactly is limiting the supply of natural rubber?'
What is the problem with how the rubber tree grows?
It can take eight to ten years for a tree to start producing rubber, so cultivating them's a slow process.
Question says → You hear
the growth of the tree iscultivating them's a slow process
Why: Eight to ten years before it produces anything makes the process slow. The gap follows 'is', so it needs an adjective: slow.
The trap: 'Don't just spring up overnight' is the same idea in an idiom, but you can't write that. The numbers don't fit after 'is' either.
Question 33
Answer: demandWhen she compares rubber with most crops
What changes that farmers can't easily react to?
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
Question says → You hear
increasing or decreasingrising or falling
Why: 'Rising or falling' matches 'increasing or decreasing', and the thing rising or falling is demand.
The trap: Crop is repeated several times, but it's what farmers change, not what goes up and down.
Question 34
Answer: equatorAfter the list of temperature, rainfall and altitude
Where in the world does the rubber tree grow?
it can't be grown in the northern or southern parts of the globe, only around the equator
Question says → You hear
only grows near theonly around the equator
Why: 'Only around' matches 'only near'. The answer is equator, and the spelling matters.
The trap: Temperature, rainfall and altitude are its needs, not where it grows. Globe is also said, but 'near the globe' makes no sense.
Question 35
Answer: recycleEnd of the supply section, when she compares rubber with water and glass
What is very hard to do with rubber after it has been produced?
when we've finished using them we can recycle them, but although this is also possible with rubber, it's very difficult
Question says → You hear
very difficult to ... rubber after productionwe can recycle them … it's very difficult
Why: Water and glass can be recycled; rubber can too, but it's very difficult. The gap follows 'to', so it needs the verb recycle.
The trap: Don't write recycling or recycled: after 'to' the base verb is the only form that fits.
Question 36
Answer: fungusUnder the new threats, after 'very little genetic diversity'
What could cause disease in the genetically similar trees?
The most dangerous threat is a fungus, which destroyed large numbers of rubber trees in Brazil
Question says → You hear
danger of disease caused by aThe most dangerous threat is a fungus
Why: 'Most dangerous threat' links to 'danger of disease', and the cause is a fungus. The 'a' before the gap means singular.
The trap: Seeds are mentioned just before, as the reason for low diversity, not the cause of disease.
Question 37
Answer: weatherThe last new threat, signposted 'And finally'
What kind of extreme events threaten supply?
South-East Asia, like other parts of the world, has been repeatedly hit by extreme types of weather
Question says → You hear
extreme ... eventsextreme types of weather
Why: The note keeps 'extreme' and needs one word to describe the events. Extreme weather events are what she means: weather.
The trap: Palm oil comes just before, but it's already in the notes as a separate threat.
Question 38
Answer: strongWhen she says 'But compared with natural rubber'
How does synthetic rubber compare with natural rubber?
But compared with natural rubber, it's not anything like as strong, and this means it can't replace natural rubber in other products.
Question says → You hear
is less ... than natural rubberit's not anything like as strong
Why: 'Not anything like as strong' means much less strong. The note needs the adjective after 'less': strong.
The trap: Don't write stronger or strength: 'less' needs the base adjective.
Question 39
Answer: rootsWhen she describes the wild plant with yellow flowers
Which part of the dandelion contains rubber?
But when it's pulled up and its roots cut open, they're found to contain rubber.
Question says → You hear
has rubber in itsits roots cut open, they're found to contain rubber
Why: The roots are cut open and found to contain rubber. 'They' tells you it's plural, so roots.
The trap: Yellow flowers are mentioned first, to describe the plant, but the rubber is in the roots.
Question 40
Answer: soilWhen she says dandelions are very adaptable
What does the dandelion not need to be good?
They'll grow in all sorts of places, and they don't need rich soil.
Question says → You hear
grown in many locationsgrow in all sorts of places
does not require goodthey don't need rich soil
Why: 'Don't need rich soil' matches 'does not require good ...'. Rich is replaced by good, so the gap is soil.
The trap: Rich is the word in the talk, but the note already has 'good' in its place. Writing rich gives 'good rich', which doesn't work.
The notes say 'extreme ... events' but the talk says 'extreme types of weather'. You have to move weather into the gap even though it isn't followed by 'events' in the recording.
'Not anything like as strong' is the clue, and the notes turn it into 'less ... than'. People who wait for the word 'less' miss it.
Words from this recording worth keeping
industrial civilisation(Introduction)
a society built on factories and machines
cultivated(Natural rubber)
grown as a crop
plantations(Natural rubber)
large farms growing one crop
labour-intensive(Limits on supply)
needing a lot of human work
genetic diversity(New threats)
variety in the genes of a population
vulnerable(New threats)
easily harmed
devastation(New threats)
very severe damage
adaptable(The dandelion)
able to live in many different conditions
Sit this test on Langujet, then come back
The full Cambridge 21 Test 1 listening paper with the real audio: all four parts, played once, marked the moment you finish. Already done it? Take it again and listen for the traps this page showed you.
Cambridge IELTS 21, Test 1, Listening Part 4. The recording, transcript and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts of the transcript only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full material, or sit the test on Langujet.
