Invasive species: listening answers and explanations
A lecturer explains what invasive species are, the harm they do and how they spread. She gives examples from Australia (cane toads) and the UK (Japanese knotweed, rhododendrons and grey squirrels), then describes how countries can monitor and control them.
One ten-gap note block in order. 31-32: 'let's look at the different ways they can be problematic'. 33-34: 'So, how do invasive species spread?'. 35-37: the examples, Australia then the UK. 38-40: 'what can we do to tackle the problem'.
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: The lecture is clearly signposted with questions ('So, how do...?'), and each one starts a new heading in the notes. Most gaps need a noun. Some answers are words she says only once, quickly, inside a longer sentence, so keep your eyes one gap ahead.
Question 31
Answer: diseaseFirst problem after 'let's look at the different ways they can be problematic'
What new thing can an invasive species bring with it?
or sometimes they may bring a disease with them, which native species have never faced before and therefore have no defences against
Question says → You hear
introduces a newbring a disease with them, which native species have never faced before
Why: 'Bring ... with them' is introduce, and 'never faced before' makes it new. The gap follows 'a new', so the noun disease.
The trap: Defences is said straight after, but that's what native species lack, not what's introduced.
Question 32
Answer: ecosystemEnd of the list of problems
What can an invasive species threaten as a whole?
Species invasions are one of the biggest causes of damage in an ecosystem, actually putting its survival at risk.
Question says → You hear
threatens an entireputting its survival at risk
Why: 'Putting its survival at risk' is threatening it, and 'its' refers to the ecosystem. Spell it carefully: ecosystem.
The trap: Environment is the general word used throughout the talk, but here she says ecosystem.
Question 33
Answer: holidayWhen she says the spread 'could be accidental'
Also accepted: holidays
Where do people accidentally bring seeds back from?
such as when people who've been on holiday in another country come back with, say, the seeds of plants on their clothes or shoes
Question says → You hear
people returning from theirpeople who've been on holiday in another country come back
Why: 'Come back' is returning, and they come back from a holiday. Holiday and holidays are both accepted.
The trap: Clothes or shoes are where the seeds are carried, not where people return from.
Question 34
Answer: petsWhen she says humans sometimes deliberately move animals and plants
Besides pest control, why do people move animals on purpose?
for example to use them to control pests on farms, or to be pets
Question says → You hear
intentionally, e.g. for pest control, or asdeliberately … to control pests on farms, or to be pets
Why: 'Deliberately' is intentionally, and the two examples match the note: pest control, then pets.
The trap: Pests and pets sound alike and come in the same sentence. Pests is already in the note as 'pest control', so the gap is pets.
Question 35
Answer: sugarWhen she introduces Rhinella marina, the toad from Hawaii
What crop were the plantations growing?
It was hoped that the toads would eat the grey-backed beetles responsible for destroying crops of sugar on many of the plantations.
Question says → You hear
a type of insect that was damagingthe grey-backed beetles responsible for destroying crops
Why: The beetles destroyed sugar crops on the plantations. The note puts it before plantations: sugar plantations.
The trap: Beetles is the insect, and it's already in the note as 'a type of insect'. Crops doesn't fit as 'the crops plantations'.
Question 36
Answer: lightWhen she moves to rhododendrons in UK parks and woodlands
What do rhododendrons stop native plants from getting?
they're now seen as harmful because they block out so much light that native wild flowers can't grow beneath them
Question says → You hear
prevent ... from reaching native plantsblock out so much light that native wild flowers can't grow
Why: 'Block out so much light' means light can't reach the plants below. Native wild flowers are the native plants.
The trap: The date 1763 comes just before, and Japanese knotweed is another plant described nearby. Neither fits this gap.
Question 37
Answer: virusWhen she says grey squirrels have outcompeted the red ones
What do grey squirrels spread that kills red squirrels?
the grey squirrels carry a type of virus that is deadly to the red squirrels
Question says → You hear
spread a ... that kills red squirrelscarry a type of virus that is deadly to the red squirrels
Why: 'Carry' is spread and 'deadly to' is kills, so the gap is virus.
The trap: Disease means something similar, and it's the answer to 31, but here the speaker says virus and the note wants that word.
Question 38
Answer: behaviourWhen she asks what we can do to tackle the problem
Also accepted: behavior
What about invasive species does monitoring help us understand?
The first step in controlling invasive species is learning about the behaviour of new species coming into the country. Monitoring is an important part of this
Question says → You hear
helps us to understand thelearning about the behaviour of new species
Why: Learning about is understanding, and what we learn about is their behaviour. British behaviour and American behavior are both accepted.
The trap: Impact is said next, but it's already in the note ('and the impact they have').
Question 39
Answer: databaseWhen she says 'One effective way to keep track of invasive species'
What national system makes tracking easier?
One effective way to keep track of invasive species is to create a database for the whole country.
Question says → You hear
Setting up a nationalcreate a database for the whole country
track themkeep track of invasive species
Why: 'For the whole country' is national, and 'create' is setting up. The gap is database.
The trap: Authorities and agencies are mentioned next as users of the database, not the thing set up.
Question 40
Answer: photographWhen she says the public also have a vital role to play
What should the public be asked to do with harmful species?
They should be encouraged to photograph harmful species - because this helps with identification - and then to report when and where these were observed.
Question says → You hear
Asking the public to ... and report themencouraged to photograph harmful species … and then to report
Why: The note keeps 'and report', so the gap is the first action: photograph, as a verb after 'to'.
The trap: She also says don't destroy or touch what you've found. Those are things not to do, so they can't go in the gap.
The toads were meant to eat beetles damaging 'crops of sugar'. The note says 'the ... plantations', so you have to lift sugar out of 'crops of sugar on many of the plantations'. Beetles is the tempting wrong word.
Grey squirrels 'carry a type of virus'. Disease was the answer to 31, which makes people write it again here, but the word she uses for the squirrels is virus.
Photograph is said as a verb ('encouraged to photograph'). People write photos or pictures, which don't fit after 'to'.
Words from this recording worth keeping
non-native(Definition)
not originally from that place
thrive(Definition)
grow or develop very well
beyond recognition(Problems)
so much that it can't be recognised
biological control(Australia)
using one living thing to control another
devastating(United Kingdom)
causing very great damage
eradicate(United Kingdom)
get rid of completely
outcompeted(United Kingdom)
did better than a rival and took its resources
monitoring(Tackling invasive species)
watching something carefully over time
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The full Cambridge 21 Test 3 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 3, 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.
