The Science of Scent: Reading Answers & Explanations
IELTS Reading practice test · 14 questionsAcademichard
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About this passage
The passage opens: “Of the human senses, smell has been the one philosophers were happiest to dismiss. Kant thought it the least rewarding of the senses and doubted it was worth cultivating; Darwin judged it of extremely slight service to modern humans.”
- Passage length: about 806 words
- Questions: 14
- Question types: Matching Headings, Summary Completion, True / False / Not Given
“The Science of Scent” is an original IELTS-style practice passage written by IELTS-Bank. It is not taken from an official IELTS or Cambridge test, so these answers only apply to our version.
Answer key at a glance
The Science of Scent answers with explanations
Questions 1–6: Matching Headings
The reading passage has six paragraphs, A-F. Choose the correct heading for each paragraph from the list of headings below.
Write the correct number, i-ix , for each paragraph.
- i. A sense wrongly written off
- ii. The chemistry of soaps and detergents
- iii. Why the same molecule divides opinion
- iv. Building a fragrance in layers
- v. How a smell is coded and sent
- vi. Machines that learn to smell
- vii. Growing flowers for the perfume trade
- viii. The shortest route to memory
- ix. How animals mark their territory
- 1
Paragraph A
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Answer: i — A sense wrongly written off
Why: Paragraph A sets out the low opinion of smell held by Kant and Darwin and the evidence that this reputation is undeserved.
- 2
Paragraph B
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Answer: v — How a smell is coded and sent
Why: Paragraph B explains the receptor family found by Buck and Axel and the combinatorial pattern by which an odour is encoded.
Where to find it · Paragraph B “What happens in the nose was obscure until 1991, when Linda Buck and Richard Axel identified the enormous family of genes that codes for odour receptors, work for which they later shared a Nobel Prize.”
- 3
Paragraph C
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Answer: iii — Why the same molecule divides opinion
Why: Paragraph C covers the unpredictable link between structure and smell and the genetic differences that make coriander taste of soap to some people.
Where to find it · Paragraph C “A small change in one receptor gene makes coriander taste of soap to a substantial minority; another leaves some people unable to smell a compound in sweat that others find overpowering.”
- 4
Paragraph D
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Answer: viii — The shortest route to memory
Why: Paragraph D describes the direct pathway to the amygdala and hippocampus and the age and emotional force of odour-cued memories.
Where to find it · Paragraph D “Signals from the olfactory bulb pass to the amygdala and hippocampus, structures central to emotion and memory, without the full relay through the thalamus that vision and hearing undergo.”
- 5
Paragraph E
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Answer: iv — Building a fragrance in layers
Why: Paragraph E describes top, heart and base notes and the fixatives that hold a fragrance together.
Where to find it · Paragraph E “A fragrance is built in layers according to how quickly its components evaporate: light top notes that announce the scent and fade within minutes, heart notes that carry it for hours, and heavy base notes and fixatives that hold the whole structure to the skin for a day.”
- 6
Paragraph F
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Answer: vi — Machines that learn to smell
Why: Paragraph F is about machine-learning models that predict odour from structure, plus the medical uses of smell testing.
Where to find it · Paragraph F “Machine-learning models trained on thousands of molecules rated by panels of human sniffers have begun to predict odour descriptions from chemical structure with accuracy approaching that of an average person, and the maps they build group molecules by how they smell rather than by how they are built.”
Questions 7–11: Summary Completion
Complete the summary below.
Complete the summary below. Choose NO MORE THAN TWO WORDS from the passage for each answer. How the nose detects an odour The human nose carries roughly four hundred working types of (7) ______ , far fewer than a mouse possesses. Buck and Axel showed that each of them answers to a range of molecules, and that each molecule sets off several of them, so a smell is registered as a (8) ______ pattern rather than by one detector on its own. The two researchers were awarded a (9) ______ for this work. Even now, chemists cannot examine a molecule's (10) ______ and predict its smell with confidence: the two mirror-image forms of carvone are perceived as caraway and (11) ______ .
- 7
Gap 7(max 2 words)
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Answer: receptor (also accepted: receptors / odour receptors / odor receptors)
Why: Paragraph B: humans have around four hundred working receptor types, far fewer than a mouse's eleven hundred.
Where to find it · Paragraph B “Humans have around four hundred working receptor types, far fewer than a mouse's eleven hundred or so, and the number alone would suggest a modest sense.”
- 8
Gap 8(max 2 words)
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Answer: combinatorial (also accepted: a combinatorial)
Why: Paragraph B states that an odour is registered as a combinatorial pattern across many channels.
Where to find it · Paragraph B “Each receptor responds to a range of molecules rather than to one, and each molecule activates a set of receptors rather than a single detector, so an odour is registered as a combinatorial pattern across many channels.”
- 9
Gap 9(max 2 words)
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Answer: nobel prize (also accepted: the nobel prize / nobel)
Why: Paragraph B says Buck and Axel later shared a Nobel Prize for identifying the odour receptor gene family.
Where to find it · Paragraph B “What happens in the nose was obscure until 1991, when Linda Buck and Richard Axel identified the enormous family of genes that codes for odour receptors, work for which they later shared a Nobel Prize.”
- 10
Gap 10(max 2 words)
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Answer: structure (also accepted: chemical structure / its structure)
Why: Paragraph C: a chemist cannot look at a molecule's structure and say with confidence what it will smell like.
Where to find it · Paragraph C “A chemist can look at a molecule and calculate its boiling point, its colour and its behaviour in solution, but cannot look at its structure and say with confidence what it will smell like.”
- 11
Gap 11(max 2 words)
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Answer: spearmint
Why: Paragraph C gives carvone as the classic case: its mirror-image forms smell of caraway and spearmint.
Where to find it · Paragraph C “The classic demonstration is carvone: its two mirror-image forms, chemically identical in almost every respect, are perceived as caraway and spearmint respectively.”
Questions 12–14: True / False / Not Given
Do the following statements agree with the information given in the reading passage? Write TRUE, FALSE or NOT GIVEN.
- 12
Mice have more working odour receptor types than humans do.
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Answer: TRUE
Why: Paragraph B gives humans about four hundred receptor types against roughly eleven hundred in a mouse.
Where to find it · Paragraph B “Humans have around four hundred working receptor types, far fewer than a mouse's eleven hundred or so, and the number alone would suggest a modest sense.”
- 13
Perfume houses protect their formulas by taking out patents on them.
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Answer: FALSE
Why: Paragraph E says formulas are almost never patented, because a patent would publish them, and are kept as trade secrets instead.
Where to find it · Paragraph E “Formulas are almost never patented, since a patent would publish them; they are kept as trade secrets inside a handful of firms that supply most of the world's perfumes, soaps and detergents.”
- 14
Most people lose their sense of smell as they grow older.
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Answer: NOT GIVEN
Why: The passage links declining smell to Parkinson's and Alzheimer's disease but makes no claim about ageing in the general population.
Closest related text · Paragraph F “A declining sense of smell is one of the earliest measurable signs of Parkinson's and Alzheimer's disease, often appearing years before diagnosis, and the sudden losses caused by viral infection have made anosmia a public concern rather than a curiosity.”
Estimated band score for this test
Your raw score out of 14 scaled to the 40-question IELTS Reading (Academic) conversion table. This is the same estimate the practice page shows after you submit. A single passage is a small sample, so treat it as a guide.
| Correct answers | Estimated band |
|---|---|
| 14 / 14 | 9.0 |
| 13 / 14 | 8.5 |
| 12 / 14 | 7.5 |
| 11 / 14 | 7.0 |
| 10 / 14 | 6.5 |
| 8–9 / 14 | 6.0 |
| 7 / 14 | 5.5 |
| 6 / 14 | 5.0 |
| 5 / 14 | 4.5 |
| 4 / 14 | 4.0 |
| 3 / 14 | 3.5 |
| 2 / 14 | 3.0 |
| 1 / 14 | 2.0 |
| 0 / 14 | 0.0 |
Full-test score? Use the IELTS band calculator.
Tips for the question types in this test
Matching Headings
- Read the list of headings first so you know the options, and notice how they differ from one another — often two headings are deliberately similar.
- Read the first paragraph and ask yourself: "In one sentence, what is this paragraph mainly saying?" before you look back at the headings.
Common trap: Picking a heading because it repeats a word from the paragraph, when that word only appears in a minor detail.
Full Matching Headings strategySummary Completion
- Read the full summary first and identify which passage section it covers.
- Predict the grammar and meaning required in every blank.
Common trap: Choosing an option only because it repeats a passage word.
Full Summary Completion strategyTrue / False / Not Given
- Read the statement first and underline the key idea, especially any qualifiers like "all", "only", "never", "always", "more than" or dates and numbers.
- Because the questions follow the order of the passage, scan for the paragraph that deals with the same topic rather than re-reading everything.
Common trap: Confusing "False" with "Not Given": choose False only when the passage actively contradicts the statement; if the passage is silent, it is Not Given.
Full True / False / Not Given strategyPractise “The Science of Scent” under exam conditions
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