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Electroreception is the opening reading passage in the British Council's free online Academic Reading practice test (Practice Test 1, Section 1). It is freely available on the official British Council Take IELTS website. The passage describes how aquatic and amphibian animals detect and use electrical signals to hunt, defend themselves, communicate, and navigate. The 13 questions test matching information to paragraphs (Q1-6), diagram labelling with no more than two words (Q7-9), and summary completion with no more than three words (Q10-13).
Passage overview at a glance
Electroreception is from the British Council's free online IELTS Academic Reading practice test (Test 1, Section 1), not from any Cambridge IELTS book. The official source is the British Council's Take IELTS website. If you found this passage in a Cambridge book test you have downloaded, your file is either mislabelled or from a different version - confirm the question numbers and wording match the ones below before using this answer key.
What the passage is about
The Electroreception passage explains how certain aquatic creatures perceive and act upon electrical signals as part of their normal sensing. It distinguishes between passive electroreception (detecting signals from other animals) and active electroreception (generating signals to probe the environment). It describes specific examples: weakly electric fish using the Jamming Avoidance Response to coordinate frequencies, ray embryos using electroreception as a defence against predators, and sharks using a combination of smell and electroreception to hunt with precision. It closes by discussing artificial electroreceptors as a possible way to repel sharks from swimming beaches, and open questions about navigation and the underlying neurology.
Complete answer key with explanations
Questions 1-6: Matching information to paragraphs
The passage has eight paragraphs labelled A-H. For each statement, identify the paragraph that contains the information. Paragraphs may be referenced more than once across the test, but each answer in this question set is a single paragraph letter A-H.
| Q# | Information to locate | Answer | Where to find it |
|---|---|---|---|
| 1 | How electroreception can be used to help fish reproduce. | C | Paragraph C describes active electroreception and notes that the special electric signals "can be used for mating signals and territorial displays". Mating = reproduction. |
| 2 | A possible use for electroreception that will benefit humans. | G | Paragraph G describes scientists exploring artificial electroreceptors that could disorient sharks and repel them from swimming beaches. That is a use of electroreception that benefits humans. |
| 3 | The term for the capacity which enables an animal to pick up but not send out electrical signals. | B | Paragraph B defines passive electroreception as the ability to "receive and decode electric signals generated by other animals" - receive but not send out. |
| 4 | Why only creatures that live in or near water have electroreceptive abilities. | A | Paragraph A states the ability "is only found in aquatic or amphibious species because water is an efficient conductor of electricity". The reason is in the same sentence as the claim. |
| 5 | How electroreception might help creatures find their way over long distances. | H | Paragraph H discusses navigation and proposes that salt water and Earth's magnetic fields may interact to form electrical currents sharks use for migration. Migration = long distance travel. |
| 6 | A description of how some fish can avoid disrupting each other's electric signals. | D | Paragraph D describes the Jamming Avoidance Response in weakly electric fish, where two fish on the same frequency shift to different frequencies to avoid jamming each other. |
Questions 7-9: Diagram labelling (NO MORE THAN TWO WORDS)
The diagram shows a ray embryo inside its egg case, with a shark approaching. Label the three numbered points using no more than two words from the passage. The information is in Paragraph E.
| Q# | Label gap | Answer | Where to find it |
|---|---|---|---|
| 7 | Shark's __________ alert the young ray to its presence. | electric signals | Paragraph E says ray embryos detect the predator through electroreception - they pick up the electric signals the shark gives off. The passage refers to the signals embryos react to as electric signals. |
| 8 | Embryo moves its __________ in order to breathe. | tail | Paragraph E states the embryos "keep their tails in constant motion so as to pump water and allow them to breathe through the egg's casing". One word - "tail" matches the gap singular. |
| 9 | Embryo stops sending __________ when predator close by. | electric current | Paragraph E explains that when the embryo detects a predator, it "stops moving (and in so doing ceases transmitting electric currents)". Two words - electric current or electric currents both accepted. |
Questions 10-13: Summary completion (NO MORE THAN THREE WORDS)
The summary is titled Shark Attack and describes how sharks hunt. Complete each gap with no more than three words from the passage. All answers come from Paragraphs F and G.
| Q# | Summary context | Answer | Where to find it |
|---|---|---|---|
| 10 | Firstly, it uses its __________ to smell its target. | olfactory organs | Paragraph F notes that "two thirds of a shark's brain is devoted entirely to its olfactory organs". Olfactory organs are what produces the keen sense of smell described in the same sentence. |
| 11 | When the shark gets close, it uses __________ to guide it toward an accurate attack. | electric signals | Paragraph F states that "as the shark reaches proximity to its prey, it tunes into electric signals that ensure a precise strike on its target". Proximity matches "gets close"; precise strike matches "accurate attack". |
| 12 | Humans are not popular food sources for most sharks due to their __________. | sinewy muscle | Paragraph G explains "our sinewy muscle does not compare well with plumper, softer prey such as seals". The unappealing texture of human muscle is why sharks are unenthusiastic. |
| 13 | Once a shark has bitten a human, a repeat attack is highly possible as salt from the blood increases the intensity of the __________. | electric field | Paragraph G says repeat attacks become likely because "the force of the electric field is heightened by salt in the blood". Force heightened = intensity increased. |
Question type strategy for this passage
Matching information to paragraphs
Q1-6 do not follow passage order - Q1 is in Paragraph C, Q4 jumps back to A. Read the question, identify the specific claim (mating, navigation, jamming, etc.), then scan the paragraph topic sentences. Do not waste time reading every paragraph fully.
Diagram labelling
Q7-9 are concentrated in Paragraph E. Read Paragraph E carefully, mark the three relevant nouns (signals, tail, current), then label the diagram. The two-word limit means you should not include articles or qualifiers.
Summary completion
Q10-13 are concentrated in Paragraphs F and G and follow passage order. Read the summary first, predict the grammatical role of each gap (noun? adjective?), then locate the matching content in F and G.
Spelling matters
"Olfactory" and "sinewy" are unusual words. They must be spelled exactly as in the passage to score the mark. Practice writing them by hand a few times - spelling errors are the easiest marks to lose on this passage.
Electroreception is a specialist topic that uses unfamiliar vocabulary (electroreception, olfactory, sinewy, lateral line). Candidates who try to apply their own knowledge of how sharks hunt rather than relying on the passage often miss the precise wording. General knowledge is irrelevant in IELTS Reading - the answer must come from the passage, in the passage's words.
Vocabulary worth learning from this passage
- Electroreception, the biological ability to detect electrical signals
- Aquatic / amphibious, living in water / living both on land and in water
- Conductor, a material that allows electricity to flow through it
- Passive vs active, receiving signals only vs generating and using signals
- Olfactory, relating to the sense of smell
- Proximity, closeness to something in space
- Sinewy, lean and tough, especially of muscle
- Disorient, to confuse someone's sense of direction or location
Related Cambridge Reading practice
For verified answer keys from the Cambridge IELTS book series, browse our Reading answers hub including William Henry Perkin from Cambridge IELTS 9 and Henry Moore from Cambridge IELTS 15. The British Council also publishes a second free practice test (Test 2) on the Take IELTS site if you want more passages in this exact style and source.
Frequently asked questions
Which Cambridge book is the Electroreception passage in?
It is not in any Cambridge IELTS book. Electroreception is from the British Council's free online IELTS Academic Reading practice test (Practice Test 1, Section 1), published on takeielts.britishcouncil.org. If a textbook or PDF claims it is Cambridge 12 or any other Cambridge book, that source has confused the British Council practice test with a Cambridge book passage.
How difficult is this passage?
Medium difficulty. The vocabulary is specialised (electroreception, olfactory, sinewy) but the passage explains the technical terms in plain language. The question mix is fair: matching information rewards skimming, diagram labelling rewards precise reading of one paragraph, summary completion rewards finding the right words rather than understanding the meaning.
Why is Q11 "electric signals" and not "electroreception"?
The instruction is "NO MORE THAN THREE WORDS from the passage". The passage says the shark "tunes into electric signals that ensure a precise strike". The exact phrase used is electric signals, not electroreception. Although electroreception is the broader ability being described, the specific words to fill the gap with are electric signals.
Can I write "electric currents" instead of "electric current" for Q9?
Yes. The passage uses the plural in "ceases transmitting electric currents". Either electric current or electric currents is accepted because the gap context (Embryo stops sending __________ when predator close by) works grammatically with both. The British Council marking key accepts singular and plural variants on this question type.
Where can I take this test in its original format?
The full original test, including the diagram for Q7-9 and the answer-sheet PDF, is on the British Council Take IELTS website under Preparing for IELTS > Practice tests > Academic Reading. It is free and no sign-up is required.