Cambridge IELTS 5 · Academic · Test 4 · Passage 3
The Effects Of Light On Plant And Animal Species — IELTS Reading Answers
All 14 answers for The Effects Of Light On Plant And Animal Species, Cambridge IELTS 5 Academic Reading Test 4 Passage 3, with the passage evidence and an explanation for each.
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The Effects Of Light On Plant And Animal Species answer key at a glance
Questions 27–40. Tap an answer to see the evidence.
What this passage tests
This passage is tested with True / False / Not Given (Q27–33), Sentence Completion (Q34–40). Each section below gives the strategy for that question type, the answers, and the sentence that proves them.
Questions 27–33: True / False / Not Given
Strategy: Judge the whole statement against the text. FALSE contradicts the passage; NOT GIVEN means the passage never addresses that specific claim.
There is plenty of scientific evidence to support photoperiodism.
“The seasonal impact of day length on physiological responses is called photoperiodism, and the amount of experimental evidence for this phenomenon is considerable”
'The amount of experimental evidence for this phenomenon is considerable', supporting the claim that there is plenty of scientific evidence.
Some types of bird can be encouraged to breed out of season.
“For example, some species of birds' breeding can be induced even in midwinter simply by increasing day length artificially (Wolfson 1964)”
Some birds' breeding 'can be induced even in midwinter simply by increasing day length artificially', so breeding out of season is possible.
Photoperiodism is restricted to certain geographic areas.
“The seasonal impact of day length on physiological responses is called photoperiodism, and the amount of experimental evidence for this phenomenon is considerable”
Photoperiodism is defined and evidenced, but the passage never says it is restricted to particular geographic regions.
Desert annuals are examples of long-day plants.
“Day-neutral plants have an evolutionary advantage when the connection between the favourable period for reproduction and day length is much less certain. For example, desert annuals germinate, flower and seed whenever suitable rainfall occurs, regardless of the day length”
Desert annuals 'germinate, flower and seed whenever suitable rainfall occurs, regardless of the day length' — they are day-neutral, not long-day.
Bamboos flower several times during their life cycle.
“Bamboos are perennial grasses that remain in a vegetative state for many years and then suddenly flower, fruit and die (Evans 1976)”
Bamboos 'remain in a vegetative state for many years and then suddenly flower, fruit and die', so they flower once, not several times.
Scientists have yet to determine the cue for Chusquea abietifolia's seasonal rhythm.
“The climatic trigger for this flowering cycle is not yet known, but the adaptive significance is clear”
'The climatic trigger for this flowering cycle is not yet known', so scientists have still to identify the cue.
Eastern hemlock is a fast-growing plant.
“Shade-tolerant plants have lower photosynthetic rates and hence have lower growth rates than those of shade-intolerant species For example, eastern hemlock seedlings are shade-tolerant”
Eastern hemlock seedlings are shade-tolerant, and shade-tolerant plants 'have lower growth rates', so it is slow-growing.
Questions 34–40: Sentence Completion
Strategy: Find the stem's keyword in the passage, then complete the sentence with the exact words the grammar requires, within the word limit.
“In the temperate zone in spring, temperatures fluctuate greatly from day to day, but day length increases steadily by a predictable amount”
The gap needs what fluctuates: 'in the temperate zone in spring, temperatures fluctuate greatly from day to day', while day length increases predictably.
“Plants which flower after a period of vegetative growth, regardless of photoperiod, are known as day-neutral plants”
The gap needs the plant type: plants flowering 'regardless of photoperiod' are 'known as day-neutral plants'.
“Thus 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”
The gap needs what nesting timing ensures: birds nest when 'adequate food resources will be assured'.
“Long-day plants are adapted for situations that require fertilization by insects, or a long period of seed ripening”
Long-day plants suit situations requiring 'fertilization by insects', so insects are the gap word.
“For example, desert annuals germinate, flower and seed whenever suitable rainfall occurs, regardless of the day length”
Desert annuals germinate 'whenever suitable rainfall occurs, regardless of the day length', so rainfall is the cue.
“Some plants reach maximal photosynthesis at one-quarter full sunlight, and others, like sugarcane, never reach a maximum, but continue to increase photosynthesis rate as light intensity rises”
The gap needs the plant that never reaches maximum photosynthesis: 'others, like sugarcane, never reach a maximum'.
“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”
The gap needs the term for the two-group division: 'this classification is commonly used in forestry and horticulture'.
Learn the question types in this passage
Frequently asked questions
Where does the The Effects Of Light On Plant And Animal Species passage come from?
It is Passage 3 of Cambridge IELTS 5 Academic Reading Test 4, and it covers Questions 27–40.
What question types appear in The Effects Of Light On Plant And Animal Species?
The passage is tested with True / False / Not Given, Sentence Completion. Each type is explained on this page, alongside the answers.
Are these reading answers reliable?
Every answer is paired with the sentence that proves it, so you can check each one against the passage yourself. Use the page after a timed attempt, not instead of one.
Cambridge IELTS is published by Cambridge University Press & Assessment. Band9Prep is not affiliated with Cambridge. This page is an independent study aid: it gives the answer key, the passage evidence and an explanation so you can review an attempt you have already made.