Table of Contents
BEST IELTS Academic Reading Test 233
IELTS ACADEMIC READING TEST – PASSAGE – 1
IELTS ACADEMIC READING TEST
READING PASSAGE – 1
Bloodsucking Creatures
Why does the world need them?
A. Of the 30,000 species of bloodsucking organisms around the world, mosquitoes are probably the best known for their attacks on humans, but there are many others. The fleshy leech will attach itself to your legs as you wade through a stream, bedbugs hidden in a mattress will silently feed on you as you sleep and a tick picked up from grassy areas can embed their mouths into your skin and spend weeks feeding off you. Blood as a food source is abundant and highly nutritious, so it makes sense that wherever there are blood-filled vertebrates, other animals have developed the ability to steal their life-sustaining fluids. Blood-feeding creatures have evolved as many as a hundred separate times in the course of the planet’s history as the behavior has cropped up independently in fish, insects, bats, birds and other animal groups, which have no common ancestor. Collectively they are called haematophages.
B. A diet that subsists mainly of blood has its complications, however, and retaining this ability over time is relatively rare when you consider the group is only 30,000 species compared to the roughly 1.6 million creatures that exist. Feeding on blood puts the body under multiple physiological strains. Firstly, a meal of blood is not nutritionally sufficient as it lacks key nutrients such as Vitamin B Complex, which help convert food into energy. Many bloodsuckers overcome this by hosting microscopic bacteria to provide these nutrients. Also the high iron content of blood causes oxidative damage and cell death, so haematophages have had to develop protective measures to counter this toxicity.
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C It is not easy getting to the blood of the host either, and blood-feeding organisms have different techniques for getting to their food. Mosquitoes inject their long thin mouthparts into the skin, while some biting flies have serrated teeth that chop through flesh. There is always the risk of a counter-attack from the host. Some creatures like leeches release anaesthetic substances present in their saliva to them remain undetected. Creatures such as vampire bats produce anticoagulants that make their victim’s blood continue flowing, even after they have gone.
D Leeches were once considered a life-saving force and used for bloodletting. This medical practice goes back to the ancient world, where it was believed that draining blood helped rebalance the body’s fluids or ‘humours’. Bloodletting was commonly practised throughout Europe, Asia and the Middle East, until as recently as the late nineteenth century. Many illnesses were treated by cutting a vein and releasing blood and it was used to treat smallpox, fevers, headaches and epilepsy. As an alternative to directly cutting into the flesh, leeches were used to let blood, as this was a painless alternative due to the anaesthetic leeches released into the skin, and it allowed for a more controlled removal of the blood.
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E Though leeches are no longer considered a universal cure-all they do still have a place in medicine today. Leech saliva contains hirudin, which is an amino acid now synthetically produced, which stops blood from clotting. This anticoagulant is used to prevent deep vein thrombosis and promote post-surgical recovery. Leeches themselves are also used in the healing process after microsurgery and skin grafts to stabilize blood clotting and enable blood vessels to reform.
F Despite leeches been valued for their healing properties, other bloodsuckers are better known for transmitting serious illnesses. Mosquitoes spread malaria, West Nile and Zika viruses, dengue fever, encephalitis and chikungunya. In fact, mosquitoes are the most lethal animal on earth if you take into account that nearly 600,000 people die of malaria each year.
G The majority of blood-feeding animals, however, do not pose much of a threat to humans, and haematophages play an important role in the balance of the ecosystem. By sucking the blood of larger animals they return nutrition to lower parts of the food chain, when they or their larvae are eaten by birds, fish, amphibians and insects. This delicate balance is under threat due to environmental problems like climate change and habitat loss. Just because a creature is unattractive or dangerous, it does not make it less worthy of being part of conversations regarding biodiversity.
IELTS Academic Reading Test
Questions 1-7
Reading Passage 1 has seven paragraphs, A-G.
Choose the correct heading for each paragraph from the list of headings below.
Write the correct number, 1-x, in boxes 1-7 on your answer sheet.
1. Paragraph A
2. Paragraph B
3. Paragraph C
4. Paragraph D
5. Paragraph E
6. Paragraph F
7. Paragraph G
List of headings
i. An alternative to a blade
ii. The dangers of bloodsucking creatures
iii. The digestion of blood
iv. Intensive scientific study
v. Their place in the world
vi. Bloodsucking creatures are all types of animals
vii. Bloodsuckers on our plates
viii. A common ancestor
ix. Methods bloodsuckers use to obtain blood
x. Current uses in medicine
IELTS Academic Reading Test
Questions 8-13
Complete the sentences below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 8-13 on your answer sheet.
8. All the varieties of bloodsuckers do not descend from the same ……………….. .
9. A large number of bloodsuckers get Vitamin B from the ……… inside them.
10. Bloodletting with leeches is ………. because they exude an anaesthetic into the skin
11. Hirudin is an ………. produced by leeches to stop blood from clotting.
12. Mosquitoes are considered particularly ……………… as they are responsible for so many deaths.
13. Most haematophages are not a ……………… to people.
IELTS Academic Reading Test
ANSWERS ARE BELOW
IELTS Academic Reading Test
ANSWERS
1. vi
2. iii
3. ix
4. i
5. x
6. ii
7. v
8. ANCESTOR
9. MICROSCOPIC BACTERIA
10. PAINLESS
11. ANTICOAGULANT
12. LETHAL
13. THREAT