IELTS Reading 練習 2 蜜蜂如何導航（含題目+詳解）

How Bees Navigate

A. Honeybees routinely travel several kilometres from the hive in search of nectar, returning with remarkable accuracy to a fixed location. Given that a foraging bee's brain contains fewer than a million neurons — one ten-thousandth the number in a human brain — its navigational abilities have long puzzled biologists. Research over the past seventy years has revealed a layered system that combines celestial cues, internal rhythms, visual memory and social communication.

B. The foundation of bee navigation is the sun compass. Even on partly cloudy days, bees can detect the polarisation pattern of ultraviolet light in patches of blue sky, allowing them to infer the sun's position. Because the sun moves across the sky during the day, bees also maintain an internal clock that adjusts this compass. Experiments in the 1950s by Karl von Frisch showed that bees trained to feed at a specific compass bearing in the morning continued to use the correct bearing in the afternoon, despite the sun having shifted.

C. Distance is measured not in metres but in "optic flow" — the rate at which visual features sweep past the bee's compound eye. A bee flying down a narrow tunnel overestimates distance because features pass quickly; in an open meadow, the same physical distance seems shorter. This rough measure is surprisingly reliable over the distances a bee typically travels.

D. Perhaps the most famous discovery is the waggle dance, performed on the vertical comb inside the hive. A returning forager traces a figure-of-eight, waggling her abdomen on the central run. The angle of this run, measured from vertical, encodes the direction of food relative to the sun; the duration of waggling encodes distance. Fellow workers decode the dance and fly to the indicated patch with errors of only a few metres even after journeys of over two kilometres.

E. Navigation is refined by landmark memory. Bees learn prominent features — a dark rock, a clump of yellow flowers — during short "orientation flights" on first leaving the hive. These memories anchor the sun-compass estimate, correcting it when wind or overcast skies introduce error.

The passage has five paragraphs, A-E. Choose the correct heading for paragraphs B, C, and E from the list below.

• i. A puzzle of scale
• ii. How direction is fixed by the sun
• iii. The role of other insects
• iv. Measuring distance through vision
• v. Fine-tuning with visual landmarks
• vi. Decoding the waggle dance

1. Paragraph B
2. Paragraph C
3. Paragraph E

1. A bee's brain has around one-tenth the number of neurons a human brain contains.
2. Karl von Frisch's experiments demonstrated that bees adjust their sun compass over time.
3. Bees use optic flow to measure distance more accurately than humans can with metres.

Complete the sentences below using NO MORE THAN THREE WORDS from the passage.

1. On cloudy days, bees can still find the sun by detecting the ______ of ultraviolet light.
2. In the waggle dance, the length of the waggle run indicates ______ to the food source.
3. New foragers build landmark memories during short ______ when they first leave the hive.

1. ii — How direction is fixed by the sun Paragraph B's topic sentence: "The foundation of bee navigation is the sun compass". The whole paragraph develops how the sun fixes direction, including the von Frisch experiment. Heading vi (waggle dance) belongs to D, not B.

2. iv — Measuring distance through vision Paragraph C opens: "Distance is measured not in metres but in 'optic flow' — the rate at which visual features sweep past the bee's compound eye". The paragraph is entirely about visual distance measurement.

3. v — Fine-tuning with visual landmarks Paragraph E opens: "Navigation is refined by landmark memory". "Refined" = "fine-tuning". The paragraph is about how landmarks correct the sun-compass estimate.

4. FALSE Supporting sentence: "one ten-thousandth the number in a human brain". The passage says 1/10,000, not 1/10. This is a classic distractor — watch the numbers carefully.

5. TRUE Supporting sentence: "Experiments in the 1950s by Karl von Frisch showed that bees trained to feed at a specific compass bearing in the morning continued to use the correct bearing in the afternoon, despite the sun having shifted". This is exactly the description of a time-adjusted compass.

6. NOT GIVEN The passage says optic flow is "surprisingly reliable" but does not compare bee accuracy with human measurement in metres. No information — choose NOT GIVEN, not TRUE.

7. polarisation pattern Supporting sentence: "bees can detect the polarisation pattern of ultraviolet light in patches of blue sky". Two words from the passage.

8. distance Supporting sentence: "the duration of waggling encodes distance". "Duration" paraphrases "length". Single-word answer.

9. orientation flights Supporting sentence: "Bees learn prominent features ... during short 'orientation flights' on first leaving the hive". Two words, exactly from passage.