Bioluminescence - IELTS Reading Answers & Explanations
From IELTS Simulation Tests Academic Reading Test 03 · Part 1 · Questions 1–13
Reading Passage
You should spend about 20 minutes on Questions 1–13, which are based on Reading Passage 1 on the following pages.
Bioluminescence
A In the pitch-black waters of the ocean's aphotic zone—depths from 1000 m to the sea floor—good eye sight does not count for very much on its own. Caves, in addition, frequently present a similar problem: the complete absence of natural light at any time of the day. This has not stopped some organisms from turning these inhospitable environments into their homes, and in the process many have created their own forms of light by developing one of the stunning visual marvels of the biological universe—bioluminescence.
B Many people will encounter bioluminescence at some point in their life, typically in some form of glow-worm, which is found on most continents. North and South America are home to the "firefly", a glowing beetle which is known as a glow-worm during its larvae stage. Flightless glowing beetles and worms are also found in Europe, Asia, Australia and New Zealand. Less common flies, centipedes, mollusks and snails have bioluminescent qualities as well, as do some mushrooms. The most dramatic examples of bioluminescence, however, are found deep below the ocean's surface, where no sunlight can penetrate at all. Here, anglerfish, cookie-cutter sharks, flashlight fish, lantern fish, gulper eels, viper fish and many other species have developed bioluminescence in unique and creative ways to facilitate their lives.
C The natural uses of bioluminescence vary widely, and organisms have learnt to be very creative with its use. Fireflies employ bioluminescence primarily for reproductive means—their flashing patterns advertise a firefly's readiness to breed. Some fish use it as a handy spotlight to help them locate prey. Others use it as a lure; the anglerfish, for example, dangles a luminescent flare that draws in gullible, smaller fishes which get snapped up by the anglerfish in an automated reflex. Sometimes bioluminescence is used to resist predators. Vampire squids eject a thick cloud of glowing liquid from the tip of its arms when threatened, which can be disorientating. Other species use a single, bright flash to temporarily blind their attacker, with an effect similar to that of an oncoming car which has not dipped its headlights.
D Humans have captured and utilised bioluminescence by developing, over the last decade, a technology known as Bioluminescence Imaging (BLI). BLI involves the extraction of a DNA protein from a bioluminescent organism, and then the integration of this protein into a laboratory animal through trans-geneticism. Researchers have been able to use luminised pathogens and cancer cell lines to track the respective spread of infections and cancers. Through BLI, cancers and infections can be observed without intervening in a way that affects their independent development. In other words, while an ultra-sensitive camera and bioluminescent proteins add a visual element, they do not disrupt or mutate the natural processes. As a result, when testing drugs and treatments, researchers are permitted a single perspective of a therapy's progression.
E Once scientists learn how to engineer bioluminescence and keep it stable in large quantities, a number of other human uses for it will become available. Glowing trees have been proposed as replacements for electric lighting along busy roads, for example, which would reduce our dependence on non-renewable energy sources. The same technology used in Christmas trees for the family home would also eliminate the fire danger from electrical fairy lights. It may also be possible for crops and plants to luminesce when they require watering, and for meat and dairy products to "tell us" when they have become contaminated by bacteria. In a similar way, forensic investigators could detect bacterial species on corpses through bioluminescence. Finally, there is the element of pure novelty. Children's toys and stickers are often made with glow-in-the-dark qualities, and a biological form would allow rabbits, mice, fish, and other pets to glow as well.
Questions
Questions 1–5 Matching Headings
Reading Passage 1 has five sections, A–E.
Choose the correct headings for sections A–E from the list of headings below.
Write the correct number, i-ix.
i. Mushrooms that glow in the dark
ii. Bright creatures on land and in the sea
iii. Evolution's solution
iv. Cave-dwelling organisms
v. Future opportunities in biological engineering
vi. Nature's gift to medicine
vii. Bioluminescence in humans
viii. Purposes of bioluminescence in the wild
ix. Luminescent pets
Questions 6–9 Four Choices
Choose FOUR letters, A–G.
Questions 10–13 Sentence Completion
Complete the sentences below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
- The luminescent fluid that a Vampire Squid emits has a 10 effect on its predator.
- In order to use bioluminescence in a trans-genetic environment, 11 must first be removed from a bioluminescent creature.
- One advantage of BLI is that it could allow researchers to see how a treatment is working without altering or disturbing 12.
- In the future, 13 may be able to use bioluminescence to identify evidence on dead bodies.
Answers & Explanations Summary
| # | Answer | Evidence | Explanation |
|---|---|---|---|
| Q1 | iii | This has not stopped some organisms from turning these inhospitable environments into their homes, and in the process many have created their own forms of light by developing one of the stunning visual marvels of the biological universe—bioluminescence | Excerpt/Passage Explanation: The passage explains that living creatures managed to live in completely dark, difficult places by creating and developing their own natural light. Answer Explanation: The answer "iii" means that the best title for Section A is "Evolution's solution". Reason For Correctness: The correct answer is iii because Section A explains a problem found in nature (complete darkness in deep ocean waters and caves) and how living creatures solved this problem over time by developing their own light, known as bioluminescence. Keywords like "inhospitable environments", "developing", and "biological universe" describe how organisms adapted naturally to survive in dark places. |
| Q2 | ii | North and South America are home to the "firefly", a glowing beetle which is known as a glow-worm during its larvae stage. Flightless glowing beetles and worms are also found in Europe, Asia, Australia and New Zealand. Less common flies, centipedes, mollusks and snails have bioluminescent qualities as well, as do some mushrooms. The most dramatic examples of bioluminescence, however, are found deep below the ocean's surface, where no sunlight can penetrate at all. Here, anglerfish, cookie-cutter sharks, flashlight fish, lantern fish, gulper eels, viper fish and many other species have developed bioluminescence in unique and creative ways to facilitate their lives | Excerpt/Passage Explanation: The passage shows examples of glowing organisms on land around the world (fireflies, beetles, worms, mushrooms) and then describes glowing creatures living deep below the ocean surface (sharks, eels, fish). Answer Explanation: The answer means choosing heading ii, which is "Bright creatures on land and in the sea". Reason For Correctness: The correct answer is ii because Section B lists many glowing living things found on land across different continents (such as glow-worms, fireflies, beetles, centipedes, and snails) as well as creatures living deep under water (such as anglerfish, sharks, flashlight fish, and eels). Therefore, the entire section describes glowing or bright animals and organisms found both on land and in the sea. |
| Q3 | viii | The natural uses of bioluminescence vary widely, and organisms have learnt to be very creative with its use | Excerpt/Passage Explanation: The passage explains that wild animals use their glowing light for many different natural reasons. Answer Explanation: The answer 'viii' means the different reasons or jobs that glowing light has for living things in nature. Reason For Correctness: The correct answer is viii because Section C explains how wild animals naturally use their glowing light. The author lists several reasons or 'purposes' for glowing in nature ('in the wild'), such as finding a mate for reproduction, hunting and spotting prey, tricking smaller fish into becoming food, and defending against predators. Key synonyms to note are 'natural uses' which matches 'in the wild', and functions like 'breeding', 'locate prey', and 'resist predators' which represent 'purposes'. |
| Q4 | vi | Researchers have been able to use luminised pathogens and cancer cell lines to track the respective spread of infections and cancers. Through BLI, cancers and infections can be observed without intervening in a way that affects their independent development | Excerpt/Passage Explanation: The passage explains that scientists can use glowing cells to watch how illnesses like infections and cancers grow and spread, without harming the natural process. Answer Explanation: The answer "vi" means that the main idea of Section D is "Nature's gift to medicine", which explains how natural glowing light helps doctors and medical scientists. Reason For Correctness: The correct answer is vi because Section D discusses how humans take bioluminescent proteins from living organisms to study diseases in medicine. Scientists use this technology to track the spread of infections and cancers and to test new drugs and therapies. Keywords such as "cancer cell lines", "infections", "drugs", "treatments", and "therapy" all relate directly to the field of "medicine". |
| Q5 | v | Once scientists learn how to engineer bioluminescence and keep it stable in large quantities, a number of other human uses for it will become available | Excerpt/Passage Explanation: The passage explains that in the future, when scientists successfully modify and control natural light-producing organisms, humans will be able to use this technology for many new purposes. Answer Explanation: The answer "v" means that Section E is best described by the heading "Future opportunities in biological engineering". Reason For Correctness: The correct answer is heading v because Section E focuses on potential future uses that humans could achieve through engineering living light. The text mentions several upcoming possibilities once scientists learn how to engineer bioluminescence at scale, including glowing street trees, plants that glow when they need water, food that signals bacterial contamination, and glowing novelty pets. Keywords like "engineer bioluminescence" and future possibilities like "will become available" and "proposed as replacements" match the idea of "future opportunities in biological engineering". |
| Q6 | — | — | |
| Q7 | — | — | |
| Q8 | — | — | |
| Q9 | A / C / F / G | Fireflies employ bioluminescence primarily for reproductive means—their flashing patterns advertise a firefly's readiness to breed. Some fish use it as a handy spotlight to help them locate prey. Others use it as a lure; the anglerfish, for example, dangles a luminescent flare that draws in gullible, smaller fishes which get snapped up by the anglerfish in an automated reflex. Sometimes bioluminescence is used to resist predators | Excerpt/Passage Explanation: The passage explains four ways creatures naturally use their glowing light: to attract a mate for breeding, to see and spot prey in the dark, to bait other creatures closer so they can eat them, and to defend themselves against enemies. Answer Explanation: The answer choices A, C, F, and G mean that in nature, living creatures make their own light to attract prey (animals they want to eat), send signals to find mates and reproduce, protect themselves against dangerous predators, and illuminate their surroundings like a flashlight to find food. Reason For Correctness: The correct answer combines options A, C, F, and G because Paragraph C specifically lists the natural purposes of bioluminescence in animals: 1. Mating signals (Option C): Fireflies use light for 'reproductive means' to show they are ready to breed. 2. A torch to identify food (Option G): Some fish use light as a 'spotlight to help them locate prey'. 3. Ways of attracting food (Option A): Some animals use light as a 'lure' that 'draws in' smaller fish to catch them. 4. Defensive tactics (Option F): Animals use light to 'resist predators' and blind attackers. Other options (tracing disease, street lighting, and drug testing) are human-made technological applications mentioned in Paragraphs D and E, not natural uses by organisms in the wild. |
| Q10 | disorientating | Vampire squids eject a thick cloud of glowing liquid from the tip of its arms when threatened, which can be disorientating | Excerpt/Passage Explanation: The passage means that when a vampire squid faces danger, it shoots out glowing liquid that confuses the attacker. Answer Explanation: The answer "disorientating" describes something that makes an attacker or predator confused and unable to tell where they are or what is happening. Reason For Correctness: The correct answer is "disorientating" because the passage explains what happens when a vampire squid is in danger from a predator. In Paragraph C, the text notes that vampire squids shoot out a glowing liquid from their arms when threatened, which has a confusing or "disorientating" effect on the attacker. Key matching words include "emits" (meaning "eject"), "luminescent fluid" (meaning "cloud of glowing liquid"), and "predator" (referring to the threat). |
| Q11 | DNA protein | BLI involves the extraction of a DNA protein from a bioluminescent organism, and then the integration of this protein into a laboratory animal through trans-geneticism | Excerpt/Passage Explanation: The passage explains that to do this scientific technique, scientists first take out a DNA protein from a glowing living creature and then put it into a lab animal. Answer Explanation: The answer refers to a specific substance or genetic molecule that comes from a living thing that produces light. Reason For Correctness: The correct answer is "DNA protein" because the passage explains that the process of Bioluminescence Imaging (BLI) begins with taking out this specific component from a creature that glows. In the text, "extraction" means being removed, "organism" means creature, and "trans-geneticism" matches the "trans-genetic environment" mentioned in the question. |
| Q12 | natural processes | In other words, while an ultra-sensitive camera and bioluminescent proteins add a visual element, they do not disrupt or mutate the natural processes | Excerpt/Passage Explanation: The passage explains that special cameras and glowing proteins let scientists watch illnesses without changing or interfering with the normal way the body works. Answer Explanation: The answer refers to the normal, biological events and changes that happen naturally inside a living body. Reason For Correctness: The correct answer is "natural processes" because the sentence asks what BLI allows researchers to observe without altering or disturbing. In Paragraph D, the text states that while cameras and glowing proteins help researchers see what is happening, "they do not disrupt or mutate the natural processes." Here, "disrupt or mutate" means the same thing as "disturb or alter." |
| Q13 | forensic investigators / scientists | In a similar way, forensic investigators could detect bacterial species on corpses through bioluminescence | Excerpt/Passage Explanation: The passage explains that in the future, crime investigators (forensic investigators) could use glowing light technology (bioluminescence) to find bacteria on dead bodies (corpses). Answer Explanation: The answer refers to crime scene investigators (police scientists) who examine evidence related to crimes and dead bodies. Reason For Correctness: The correct answer is "forensic investigators" because the question asks who might use bioluminescence in the future to find evidence on dead bodies. Paragraph E explains that "forensic investigators could detect bacterial species on corpses through bioluminescence." The word "corpses" in the passage matches "dead bodies" in the sentence, and "detect bacterial species" matches finding evidence. |