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IELTS Practice Reading: Label Diagram ID: #56237 Hard The seawater
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The seawater greenhouse as developed by Paton has three main parts. They both air-condition the greenhouse and provide water for irrigation. The front of the greenhouse faces into the prevailing wind so that hot dry air blows in through a front wall. The wall is made of perforated cardboard kept moist by a constant trickle of seawater pumped up from the ocean. The purpose is to cool and moisten the incoming desert air. The cool moist air allows the plants to grow faster. And, crucially, because much less water evaporates from the leaves, the plants need much less moisture to grow than if they were being irrigated in the hot dry desert air outside the greenhouse.
The air-conditioning of the interior of the greenhouse is completed by the second feature: the roof. It has two layers: an outer layer of clear polyethylene and an inner coated layer that reflects infrared radiation. This combination ensures that visible light can stream through to the plants, maximizing the rate of plant growth through photosynthesis but at the same time heat from the infrared radiation is trapped in the space between the layers, and kept away from the plants. This helps keep the air around the plants cool.
At the back of the greenhouse sits the third elements. This is the main water production unit. Here, the air hits a second moist cardboard wall that increases its humidity as it reaches the condenser, which finally collects from the hot humid air the moisture for irrigating the plants. The condenser is a metal surface kept cool by still more seawater. It is the equivalent of the window on Paton’s Morcoccan bus. Drops of pure distilled water from on the condenser and flow into a tank for irrigating the crops.
5 labels
Diagram
Options:
hot dry air
cardboard
infrared radiation
moist
photosynthesis
pure distilled water
condenser
independent grid
AI explanationShows the answer. Tap to open.

Question Focus: The diagram shows air entering the greenhouse through the front wall and asks what condition the wall is kept in.

Correct Answer: D

Why this is correct: The diagram shows the front wall where air enters. The passage clearly says the wall is kept moist by seawater, so the correct label is moist.

Passage Reference: The wall is made of perforated cardboard kept moist by a constant trickle of seawater pumped up from the ocean.

Common Mistake: Some students choose cardboard because the wall material is mentioned. But the diagram blank asks about the wall's condition, not what it is made from. This is a context shift trap.

Paraphrasing: Passage: 'kept moist' = Diagram: 'wall is ___'

Tips: Check whether the diagram blank asks about a thing or a description of that thing.

Key Vocabulary:

  • moist = slightly wet
  • trickle = small slow flow

Question Focus: The diagram labels what type of heat is reflected by the inner roof layer.

Correct Answer: C

Passage Reference: It has two layers: an outer layer of clear polyethylene and an inner coated layer that reflects infrared radiation. This combination ensures that visible light can stream through to the plants, maximizing the rate of plant growth through photosynthesis but at the same time heat from the infrared radiation is trapped in the space between the layers, and kept away from the plants.

Why this is correct: The diagram points to the inner roof layer. The passage says this layer reflects infrared radiation, keeping heat away from the plants. So the answer is infrared radiation.

Common Mistake: Students sometimes choose photosynthesis because plant growth is mentioned nearby. But photosynthesis needs light, not heat reflection. This is a wrong section trap.

Paraphrasing: Passage: 'infrared radiation' = Diagram: 'type of heat'

Tips: When two ideas appear close together, match the diagram arrow to the exact object it points to.

Key Vocabulary:

  • infrared = heat energy
  • reflect = send back

Question Focus: The diagram shows what substance is collected and stored for irrigation.

Correct Answer: F

Passage Reference: Drops of pure distilled water from on the condenser and flow into a tank for irrigating the crops

Why this is correct: The diagram shows water flowing into a tank. The passage says pure distilled water drops from the condenser and flows into a tank. So the label must be pure distilled water.

Common Mistake: Some students pick hot dry air because air is discussed a lot. But the diagram here shows liquid going into a tank, not air movement. This is a context shift trap.

Paraphrasing: Passage: 'pure distilled water' = Diagram: 'water collected'

Tips: Look at arrows and containers in diagrams to decide if the answer is a gas, liquid, or solid.

Key Vocabulary:

  • distilled = purified
  • irrigating = watering crops

Question Focus: The diagram labels the part at the back of the greenhouse that collects water.

Correct Answer: G

Passage Reference: as it reaches the condenser, which finally collects from the hot humid air the moisture for irrigating the plants. The condenser is a metal surface kept cool by still more seawater.

Why this is correct: The diagram position is at the back where water is produced. The passage says air reaches the condenser, which collects moisture. So the answer is condenser.

Common Mistake: Students may choose cardboard because another wall is mentioned here. But the diagram points to the water-collecting device, not the wall. This is a partial truth trap.

Paraphrasing: Passage: 'the condenser' = Diagram: 'water collection unit'

Tips: For process diagrams, follow the sequence from front to back as described in the passage.

Key Vocabulary:

  • condenser = cooling surface
  • humidity = moisture in air

Question Focus: The diagram shows what kind of air enters the greenhouse from outside.

Correct Answer: A

Passage Reference: so that hot dry air blows in through a front wall.

Why this is correct: The diagram shows outside air entering the greenhouse. The passage clearly says hot dry air blows in through the front wall. So the correct label is hot dry air.

Common Mistake: Some students choose moist because air later becomes moist inside. But the question asks about the air before it is treated. This is a time/tense trap.

Paraphrasing: Passage: 'hot dry air blows in' = Diagram: 'air entering greenhouse'

Tips: Check whether the diagram stage is before or after a process described in the passage.

Key Vocabulary:

  • prevailing = usual
  • desert = very dry area

General Tips:

  • Diagram questions follow passage order, so start at the beginning and move step by step.
  • Always read the full sentence in the passage, not just one matching word.
  • Use arrows and position in the diagram to understand the process stage.
  • Cross out used options so you do not reuse them by mistake.

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