Why do some leaves turn red in autumn? Yellow and orange simply show through as chlorophyll is broken down, but red pigments are made new, which costs energy. After rejecting several theories, the writer favours the idea that red pigment shields weakened leaves from too much light, and lists the evidence.
The paragraph matching (14-18) uses B twice and also needs C, E and H. The notes (19-22) are all in H. The TRUE / FALSE / NOT GIVEN statements (23-25) come from D, F and I, and the multiple choice (26) goes back to B.
Answer key and self-check
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Q
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Answer
Questions 14-18 · Matching information (paragraphs A-I)
How to attack this block: B holds two answers: why trees drop their leaves and what chlorophyll does. Separate the theory paragraphs carefully: F states the light-screen idea, but the evidence for it is in H, and the warning-signal idea is in E.
Question 14
Answer: CParagraph C, first two sentences
Which paragraph describes the substance that makes leaves red?
The source of the red is widely known: it is created by anthocyanins, water-soluble plant pigments reflecting the red to blue range of the visible spectrum.
Question says → Passage says
the substance responsible for the red colourationThe source of the red… anthocyanins
a descriptionwater-soluble plant pigments… sugar-based chemical compounds also known as flavonoids
Why: C names anthocyanins and then describes them: water-soluble pigments, sugar-based, part of the flavonoid group. That's a description of the substance.
The trap: F and G mention 'the red pigment' too, but they're about what it might be for, not what it is.
Question 15
Answer: BParagraph B, second to fourth sentences
Which paragraph explains why trees drop their leaves in autumn?
So rather than maintaining the now redundant leaves throughout the winter, the tree saves its precious resources and discards them.
Question says → Passage says
the reason whyAs fall approaches… the amount of solar energy available declines considerably
trees drop their leavesdiscards them
Why: With less sunlight, photosynthesis isn't worth it, so the leaves become 'redundant'. Keeping them would waste resources, so the tree discards them. That's the reason.
The trap: G talks about the leaf 'preparing for winter', but it explains why autumn leaves are vulnerable to light, not why they fall.
Question 16
Answer: HParagraph H
Which paragraph gives evidence supporting a theory about why leaves turn red?
Even if you had never suspected that this is what was going on when leaves turn red, there are clues out there.
Question says → Passage says
some evidencethere are clues out there
confirm a theoryconditions that nicely match those that make leaves susceptible to excess light
Why: H lists clues that fit the light-screen idea: the sunniest side is reddest, the upper surface is redder, sunny dry days help, and trees further north are redder. Clues are evidence.
The trap: F introduces the light-screen hypothesis, so it's tempting, but F only states the theory and raises questions. The evidence comes in H. E even says its theory has no proof.
Question 17
Answer: BParagraph B, first sentence
Which paragraph explains what chlorophyll does?
chlorophyll, the molecule that captures sunlight and converts that energy into new building materials for the tree
Question says → Passage says
the function of chlorophyllcaptures sunlight and converts that energy into new building materials
Why: B's first sentence defines chlorophyll's job: capture sunlight and turn it into building materials. That's its function, so B is used a second time.
The trap: G opens with chlorophyll 'evolved to capture the energy of sunlight', which looks similar. G's point is how chlorophyll can be overwhelmed, not what it normally does.
Question 18
Answer: EParagraph E, first two sentences
Which paragraph suggests red leaves could be a warning?
trees may produce vivid red colours to convince herbivorous insects that they are healthy and robust and would be easily able to mount chemical defences against infestation
Question says → Passage says
could serve as a warning signalto convince herbivorous insects… / If insects paid attention to such advertisements
Why: The red tells insects 'I'm strong and can defend myself, go elsewhere'. A message meant to put attackers off is a warning signal.
The trap: D also mentions defence against insects, but there the pigment is a chemical defence itself, not a signal. E is the one about advertising strength.
Note completion (ONE WORD ONLY)
Questions 19-22
How to attack this block: H gives four clues in the same order as the notes. Each gap needs one exact word: where the reddest leaves face, which leaf surface, what daytime weather besides sunny, and which direction.
Question 19
Answer: sunParagraph H, second sentence
Also accepted: sunlight
Which side of the tree has the reddest leaves?
on many trees, the leaves that are the reddest are those on the side of the tree which gets most sun
Question says → Passage says
the most vividly coloured red leavesthe leaves that are the reddest
facing thewhich gets most sun
Why: The side that gets the most sun is the side facing the sun. One word: 'sun' ('sunlight' is also accepted).
The trap: 'South' is a common guess based on general knowledge, but the passage never says it. Write the passage's word.
Question 20
Answer: upperParagraph H, third sentence
Which surface of the leaf has most red pigment?
Not only that, but the red is brighter on the upper side of the leaf.
Question says → Passage says
the … surfaces of leavesthe upper side of the leaf
contain the most red pigmentthe red is brighter
Why: Brighter red means more pigment, and it's on the upper side. The gap needs an adjective before 'surfaces', so 'upper'.
The trap: Don't write 'upper side', which repeats the idea of 'surfaces' and breaks the one-word limit.
Question 21
Answer: dryParagraph H, fourth sentence
Along with sunny, what kind of daytime weather gives the most red leaves?
the best conditions for intense red colours are dry, sunny days and cool nights
Question says → Passage says
daytime weather conditionsdays
… and sunnydry, sunny
Why: The notes already give 'sunny', so the other daytime word is 'dry'.
The trap: 'Cool' is in the same phrase, but it describes the nights, and the note asks about daytime.
Question 22
Answer: northParagraph H, last two sentences
In which direction does red get more intense as you travel?
trees such as maples usually get much redder the more north you travel in the northern hemisphere
Question says → Passage says
the intensity of the red colour … increasesget much redder
as you go furtherthe more north you travel
Why: 'Get much redder' is the intensity increasing, and that happens the further north you go. One word: 'north'.
The trap: 'Northern' comes later in the same sentence, but 'further northern' isn't grammatical. The gap needs the direction itself.
TRUE / FALSE / NOT GIVEN
Questions 23-25
How to attack this block: The FALSE is a theory the writer lists and then rejects. The TRUE turns on 'paradoxical'. The NOT GIVEN comes from the last paragraph, where the writer asks a question rather than answering it.
Question 23
Answer: FALSEParagraph D
Do red pigments probably help protect leaves from freezing?
or increase a leaf's tolerance to freezing. However there are problems with each of these theories
Question says → Passage says
protect the leaf from freezing temperaturesincrease a leaf's tolerance to freezing
it is likelythere are problems with each of these theories
Why: Freezing tolerance is one of the theories D lists, and the writer immediately says each of them has problems. So the writer thinks it's unlikely, which contradicts 'likely': FALSE.
The trap: Some readers choose NOT GIVEN because no study is mentioned. But the writer clearly rejects these theories, and that's a contradiction.
Question 24
Answer: TRUEParagraph F, second and third sentences
Does the light-screen idea seem at first to go against what we know about chlorophyll?
It sounds paradoxical, because the idea behind this hypothesis is that the red pigment is made in autumn leaves to protect chlorophyll, the light-absorbing chemical, from too much light.
Question says → Passage says
would initially seem to contradictIt sounds paradoxical
what is known about chlorophyllthe natural world's supreme light absorber
Why: 'Paradoxical' means it seems self-contradictory: why protect the world's best light absorber from light? 'Sounds' matches 'initially seem'. TRUE.
The trap: G then shows the hypothesis makes sense after all, so some people pick FALSE. The statement only says it 'would initially seem' contradictory, which is exactly F's point.
Question 25
Answer: NOT GIVENParagraph I
Are leaves that turn other colours more likely to suffer sun damage?
Do these trees have other means at their disposal to prevent overexposure to light in autumn?
Question says → Passage says
leaves which turn colours other than redothers don't bother, and simply reveal their orange or yellow hues
Why: The writer only asks whether yellow and orange trees have other ways to protect themselves, and says this isn't understood yet. Nothing says they're more damaged. NOT GIVEN.
The trap: Logic suggests that without red 'sunblock' they'd be at more risk, so people pick TRUE. The writer leaves the question open, and the next sentence hints they may have their own subtle protection.
Multiple choice
Question 26
How to attack this block: Only one of these questions gets an actual explanation in the passage. The others are mentioned in passing or described as still unknown, so check each against what the writer really explains.
Question 26
Answer: BParagraph B, last two sentences
Which of these questions does the writer actually explain?
As chlorophyll is depleted, other colours that have been dominated by it throughout the summer begin to be revealed. This unmasking explains the autumn colours of yellow and orange
Question says → Passage says
how leaves turn orange and yellowThis unmasking explains the autumn colours of yellow and orange
Why: When the green chlorophyll is broken down, the yellow and orange that were hidden show through. The writer uses the word 'explains', so B.
The trap: A tempts because conifers are mentioned, but only in passing as an exception, with no reason given. C and D are things the writer says are still unknown (E and I).
'Dry'. 'Cool' is in the same phrase, but it describes the nights, and the note asks about daytime.
Words from this passage worth keeping
captivating(A)
very attractive and holding your attention
redundant(B)
no longer needed or useful
depleted(B)
reduced in amount until little is left
newly minted(C)
freshly made
outweigh(D)
be greater or more important than
plausible(F)
reasonable and likely to be true
paradoxical(F)
seeming to contradict itself
susceptible(H)
easily affected or harmed by something
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Cambridge IELTS 10, Test 3, Reading Passage 2. The passage and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full text, or sit the test on Langujet.
