Light matters to living things in two ways. Day length acts as a reliable cue for breeding in birds and flowering in short-day and long-day plants, while day-neutral plants ignore it. Light also drives photosynthesis, and plants divide into shade-tolerant, slow-growing species and shade-intolerant, faster-growing ones.
Questions 27-40 · 14 marks · 2 question blocks
The TRUE / FALSE / NOT GIVEN block (27-33) runs through the whole passage in order. The sentence completion (34-40) starts again at paragraph 2 and also follows passage order to the end.
Type what you wrote and hit mark. Hide the key first if you haven't done the passage yet. Every question number jumps to its explanation.
| Q | Your answer | Answer |
|---|---|---|
| Questions 27-33 · TRUE / FALSE / NOT GIVEN | ||
| 27 | TRUE | |
| 28 | TRUE | |
| 29 | NOT GIVEN | |
| 30 | FALSE | |
| 31 | FALSE | |
| 32 | TRUE | |
| 33 | FALSE | |
| Questions 34-40 · Sentence completion (NO MORE THAN THREE WORDS) | ||
| 34 | temperatures | |
| 35 | day-neutralAlso accepted: day-neutral plants / day neutral plants | |
| 36 | foodAlso accepted: food resources / adequate food / adequate food resources | |
| 37 | insectsAlso accepted: fertilization by insects | |
| 38 | rainfallAlso accepted: suitable rainfall | |
| 39 | sugarcane | |
| 40 | classification | |
How to attack this block: Several FALSEs need you to connect two ideas: desert annuals are day-neutral, and shade-tolerant plants grow slowly. The NOT GIVEN treats examples from the temperate zone as if they were a limit.
Is there a lot of scientific evidence for photoperiodism?
The seasonal impact of day length on physiological responses is called photoperiodism, and the amount of experimental evidence for this phenomenon is considerable.
Question says → Passage says
Why: TRUE. 'Considerable' means a large amount, and 'experimental evidence' is scientific evidence.
Can some birds be made to breed outside their usual season?
some species of birds' breeding can be induced even in midwinter simply by increasing day length artificially
Question says → Passage says
Why: TRUE. Birds that normally breed in spring can be made to breed in midwinter with artificial light. 'Induced' is 'encouraged'.
Is photoperiodism found only in certain parts of the world?
In the temperate zone in spring, temperatures fluctuate greatly from day to day, but day length increases steadily by a predictable amount.
Question says → Passage says
Why: NOT GIVEN. The examples come from the temperate zone, but the passage never says photoperiodism happens only there, or that it doesn't happen elsewhere.
The trap: Because every example is temperate, it feels restricted, so people write TRUE. Examples aren't limits.
Are desert annuals long-day plants?
Day-neutral plants have an evolutionary advantage… For example, desert annuals germinate, flower and seed whenever suitable rainfall occurs, regardless of the day length.
Question says → Passage says
Why: FALSE. Desert annuals are given as an example of day-neutral plants, which flower 'regardless of the day length'. A long-day plant depends on day length, so they can't be both.
The trap: The sentence right before is about day-neutral plants, but long-day plants are discussed earlier in the same paragraph. Check which sentence the 'For example' belongs to.
Do bamboos flower many times in their life?
Bamboos are perennial grasses that remain in a vegetative state for many years and then suddenly flower, fruit and die
Question says → Passage says
Why: FALSE. Bamboos flower once, then die. Flowering several times contradicts 'flower, fruit and die'.
The trap: The Jamaican bamboo flowered in 1884 and again in 1916-18, which looks like repeated flowering. But that was 'the next generation', not the same plants.
Do scientists still not know what triggers Chusquea abietifolia's flowering cycle?
The climatic trigger for this flowering cycle is not yet known, but the adaptive significance is clear.
Question says → Passage says
Why: TRUE. 'Not yet known' is 'have yet to determine', and 'trigger' matches 'cue'.
The trap: 'The adaptive significance is clear' in the same sentence can make you think the cause is known. Significance (why it helps) is clear; the trigger isn't.
Does eastern hemlock grow fast?
Shade-tolerant plants have lower photosynthetic rates and hence have lower growth rates… eastern hemlock seedlings are shade-tolerant
Question says → Passage says
Why: FALSE. Eastern hemlock is shade-tolerant, and shade-tolerant plants have lower growth rates. The passage also says it has a low photosynthetic rate. So it grows slowly.
The trap: You have to connect two sentences, so some students stop at the hemlock sentence and write NOT GIVEN. The general rule earlier in the paragraph applies to it.
How to attack this block: The sentences paraphrase closely, so look for the partner phrase (unpredictable, no limit, criterion). Most answers are single nouns, and several have accepted longer versions. Watch plurals: temperatures, insects.
What is unpredictable in the areas where day length is a useful breeding cue?
In the temperate zone in spring, temperatures fluctuate greatly from day to day, but day length increases steadily by a predictable amount.
Question says → Passage says
Why: The sentence contrasts unpredictable temperatures with predictable day length. The gap needs a plural noun because of 'are': 'temperatures'.
The trap: 'Day length' is the predictable thing, the opposite of what the gap wants. Make sure you write 'temperatures' with the s.
Also accepted: day-neutral plants / day neutral plants
What are plants that don't respond to light levels called?
Plants which flower after a period of vegetative growth, regardless of photoperiod, are known as day-neutral plants.
Question says → Passage says
Why: 'Regardless of photoperiod' means they ignore day length. 'Day-neutral' or 'day-neutral plants' both fit the three-word limit.
The trap: 'Short-day' and 'long-day' plants are in the same paragraph, but both respond to day length.
Also accepted: food resources / adequate food / adequate food resources
What do temperate birds link longer days with, apart from nesting?
many temperate-zone birds use the increasing day lengths in spring as a cue to begin the nesting cycle, because this is a point when adequate food resources will be assured
Question says → Passage says
Why: Longer days signal both nesting time and a guaranteed food supply. 'Food', 'food resources' or 'adequate food' are all accepted.
The trap: 'Food reserves' appears earlier in the paragraph, but that's what birds build up in their bodies before breeding, not what longer days signal.
Also accepted: fertilization by insects
What do long-day plants often need to reproduce?
Long-day plants are adapted for situations that require fertilization by insects, or a long period of seed ripening.
Question says → Passage says
Why: 'Help them reproduce' is fertilization, and the helpers are insects. 'Insects' or 'fertilization by insects' both fit.
The trap: 'Seed ripening' is the other half of the sentence, but it's a process, not something the plant depends on to reproduce.
Also accepted: suitable rainfall
What do desert annuals treat as their signal to reproduce?
desert annuals germinate, flower and seed whenever suitable rainfall occurs, regardless of the day length
Question says → Passage says
Why: They reproduce 'whenever suitable rainfall occurs', so rain is the signal. 'Rainfall' or 'suitable rainfall' is accepted.
The trap: 'Day length' is in the same sentence, but desert annuals ignore it.
Which plant's photosynthetic rate never reaches a maximum?
others, like sugarcane, never reach a maximum, but continue to increase photosynthesis rate as light intensity rises
Question says → Passage says
Why: 'No limit' matches 'never reach a maximum', and the example given is sugarcane, written as one word.
The trap: 'Eastern hemlock' is the other named plant, but it has a low photosynthetic rate, the opposite.
Shade tolerance is a basis for what in forestry and horticulture?
Plants in general can be divided into two groups: shade-tolerant species and shade-intolerant species. This classification is commonly used in forestry and horticulture.
Question says → Passage says
Why: Dividing plants by shade tolerance is a classification, and the passage uses that noun. The gap needs a noun after 'the'.
The trap: 'Groups' or 'division' sound close, but the key wants the passage's own word, 'classification'.
FALSE. You have to link two sentences: hemlock is shade-tolerant, and shade-tolerant plants grow more slowly.
FALSE. The bamboo flowering in 1884 and again in 1916-18 was a new generation, because each plant flowers once and dies.
NOT GIVEN. The examples come from the temperate zone, but the passage never says photoperiodism is limited to it.
The full Cambridge 5 Test 4 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 5, Test 4, Reading Passage 3. 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.
