Bacaan
Sleeping With One Eye Open
(1) For most mammals, sleep is an all-or-nothing state: the whole brain slows down together, and the body becomes still and largely unaware of its surroundings. A number of animals, however, have found a way around this risky arrangement. They can let one half of the brain sink into deep sleep while the other half stays awake. Scientists call this unihemispheric slow-wave sleep.
(2) Bottlenose dolphins are the best-known example. A dolphin has to swim up to the surface for every breath, so it cannot simply drift off for hours the way a person does in bed. By resting one half of the brain at a time, a dolphin can keep swimming, surfacing, and watching for danger while still getting the sleep it needs.
(3) Birds use the same trick. In a well-known experiment published in 1999, researchers filmed mallard ducks sleeping side by side in a row and recorded their brain activity. The ducks at the two ends of the row, which were the most exposed, spent much more time sleeping with one half of the brain than the ducks in the middle. They also tended to keep open the eye facing away from the group, the direction from which a predator would most likely come. Each open eye was linked to the half of the brain that was still awake.
(4) Some birds even sleep in the air. In 2016, scientists who recorded the brain activity of great frigatebirds during long flights over the ocean found that the birds slept mostly while circling upward in rising air, often with only one half of the brain at a time. In flight, however, they slept for less than an hour a day in total, compared with more than twelve hours a day once they were back on land.
(5) Humans cannot do anything as dramatic, but traces of the same idea may exist in us. A 2016 study of people sleeping in a laboratory for the first time found that, on the first night, the left half of the brain slept less deeply than the right and responded more strongly to unusual sounds. On the second night, the difference disappeared. The researchers suggested that this "night watch" may help explain why many people sleep poorly in a new place.
Soal 1
Pilih satu jawabanAccording to the passage, what did the ducks at the ends of the row do?
Lihat kunci & pembahasan
Kunci: E
Kenapa benar
Paragraf (3) menyatakan bebek di kedua ujung barisan lebih sering tidur dengan separuh otak dan cenderung membuka mata yang menghadap ke luar kelompok, yaitu arah datangnya pemangsa. Jadi jawabannya adalah mata yang menghadap menjauhi kelompok tetap terbuka.
Langkah
Cari frasa ends of the row di teks: ada di paragraf (3).
Baca kalimat sesudahnya: "They also tended to keep open the eye facing away from the group".
Cocokkan dengan pilihan yang memuat informasi yang sama dengan kata lain.
Tips: untuk soal according to the passage, jawaban harus tertulis di teks. Jangan menambahkan dugaan sendiri.
Kenapa opsi lain salah
- A.
Teks tidak membandingkan lama tidur total bebek di ujung dan di tengah. Yang dibandingkan adalah seberapa sering mereka tidur dengan separuh otak.
- B.
Bergantian berjaga terdengar masuk akal, tetapi tidak disebut sama sekali dalam teks.
- C.
Ini kebalikan isi teks. Bebek di ujung justru lebih sering tidur dengan satu separuh otak dibanding bebek di tengah.
- D.
Teks tidak menyebut kedua mata terbuka atau suara pemangsa. Yang disebut hanya satu mata yang menghadap ke luar.
Konsep
Menemukan informasi tersurat dengan memindai kata kunci soal di teks, lalu mencocokkan parafrasenya di pilihan jawaban.
Jebakan umum
Memilih pernyataan yang logis menurut pengetahuan umum padahal tidak tertulis di teks.
Referensi
- Wikipedia, "Unihemispheric slow-wave sleep"
- Rattenborg, Lima & Amlaner (1999), "Half-awake to the risk of predation", Nature 397
- Rattenborg dkk. (2016), "Evidence that birds sleep in mid-flight", Nature Communications 7:12468
- Tamaki dkk. (2016), "Night watch in one brain hemisphere during sleep associated with the first-night effect in humans", Current Biology 26(9)
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