IELTS Reading 練習 植物的溝通（含題目+詳解）

Plant Communication

A. Plants are easy to dismiss as passive, since they neither move nor make sounds in any sense the human ear can hear. A growing body of research over the past forty years suggests, however, that plants exchange a great deal of information — both with each other and with the animals around them — through chemical, electrical and even microbial channels. None of this counts as language in the strict sense, but the parallels with animal signalling are striking enough that botanists now routinely speak of plant "communication".

B. The best-studied channel involves volatile organic compounds, or VOCs — gases released into the air from leaves under stress. When a tobacco plant is attacked by caterpillars, it emits a distinctive cocktail of VOCs that drifts to neighbouring plants. The neighbours, on detecting these molecules, increase their own production of bitter defensive chemicals before any caterpillar has reached them. The signalling plant is not acting altruistically; it is simply releasing the compounds as part of its own defence, and others happen to overhear. Even so, the effect on the wider community is real.

C. A second channel runs underground. Most land plants form symbiotic associations with networks of fungal hyphae — the mycorrhizal network, sometimes nicknamed the "wood wide web". Researchers led by Suzanne Simard have shown that older trees can transfer carbon, water and small organic molecules through these networks to nearby seedlings of the same species, and that warning signals about pest attack can travel through the same fungal threads. The relationship benefits the fungus, which receives sugars in return, but it also stitches the forest into something closer to a community than a collection of individuals.

D. A third, more controversial channel uses electrical signals carried within the plant itself. When a leaf is wounded, a slow voltage change propagates through the vascular tissue at roughly one millimetre per second, triggering the release of defensive chemicals in distant leaves. The mechanism resembles a nerve impulse in extreme slow motion, although plants of course have no neurons, and many botanists are uneasy with comparisons to animal nervous systems.

E. None of these systems implies that plants think or feel in the way animals do. What they do show is that the apparent stillness of a meadow or a forest hides a continual exchange of information — chemical, fungal and electrical — that helps each plant respond to threats it has not yet directly encountered.

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

• i. Slow signals along the vascular system
• ii. A reframing of plants as active senders
• iii. Airborne warnings carried by VOCs
• iv. Underground links through fungal threads
• v. Why plants do not think
• vi. Loud chemical alarms above the canopy

1. Paragraph B
2. Paragraph C
3. Paragraph D

1. Tobacco plants under attack release VOCs primarily to help neighbouring plants.
2. The mycorrhizal network is sometimes called the "wood wide web".
3. Plants and animals use the same nerve cells to carry electrical signals.

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

1. Older trees can transfer carbon, water and small organic molecules to nearby ______ of the same species.
2. The fungus in a mycorrhizal network receives ______ from its plant partner in exchange for help.
3. Wound-triggered voltage changes propagate through the plant's vascular tissue at roughly one ______ per second.

1. iii — Airborne warnings carried by VOCs Paragraph B introduces VOCs and explains how they drift through the air to neighbouring plants. "Airborne warnings" matches; vi is a trap because nothing in the passage describes the alarms as "loud" or "above the canopy".

2. iv — Underground links through fungal threads Paragraph C is entirely about the mycorrhizal network of fungal hyphae. "Underground" and "fungal threads" both match.

3. i — Slow signals along the vascular system Paragraph D: "a slow voltage change propagates through the vascular tissue at roughly one millimetre per second". "Slow signals along the vascular system" is a direct paraphrase.

4. FALSE Supporting sentence: "The signalling plant is not acting altruistically; it is simply releasing the compounds as part of its own defence, and others happen to overhear". Not "primarily to help neighbours". Direct contradiction.

5. TRUE Supporting sentence: "the mycorrhizal network, sometimes nicknamed the 'wood wide web'". Direct paraphrase.

6. FALSE Supporting sentence: "plants of course have no neurons". The statement contradicts the explicit fact that plants lack neurons.

7. seedlings Supporting sentence: "older trees can transfer carbon, water and small organic molecules through these networks to nearby seedlings of the same species". Single-word answer.

8. sugars Supporting sentence: "The relationship benefits the fungus, which receives sugars in return". Single-word answer.

9. millimetre Supporting sentence: "a slow voltage change propagates through the vascular tissue at roughly one millimetre per second". Single-word answer; the question supplies "one" and "per second".