Plant Thermometer Trigger – IELTS Reading Answers

‘Plant Thermometer Trigger’ is an academic reading passage that has appeared in an IELTS Test. Since questions get repeated in the IELTS exam, these kinds of reading passages are ideal for practice. If you want more practice, try taking a whole IELTS reading practice test.

Since IELTS Reading is considered the second easiest module of the exam after Listening, try to solve and review the ‘Plant Thermometer Trigger’ Reading passage and similar passages to ensure that your reading skills are up to the mark.

The question types found in the ‘Plant Thermometer Trigger’ passage are:

• True/False/Not Given (Q. 1-5)
• Matching Features (Q. 7-11)
• Sentence Completion (Q. 12-14)

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Reading Passage

Plant ‘thermometer’ triggers springtime growth by measuring night-time heat

A photoreceptor molecule in plant cells has been found to have a second job as a thermometer after dark – allowing plants to read seasonal temperature changes. Scientists say the discovery could help breed crops that are more resilient to the temperatures expected to result from climate change

1. An international team of scientists led by the University of Cambridge has discovered that the ‘thermometer’ molecule in plants enables them to develop according to seasonal temperature changes. Researchers have revealed that molecules called phytochromes – used by plants to detect light during the day – actually change their function in darkness to become cellular temperature gauges that measure the heat of the night. The new findings, published in the journal Science, show that phytochromes control genetic switches in response to temperature as well as light to dictate plant development.
2. At night, these molecules change states, and the pace at which they change is ‘directly proportional to temperature’, say scientists, who compare phytochromes to mercury in a thermometer. The warmer it is, the faster the molecular change – stimulating plant growth.
3. Farmers and gardeners have known for hundreds of years how responsive plants are to temperature: warm winters cause many trees and flowers to bud early, something humans have long used to predict weather and harvest times for the coming year. The latest research pinpoints for the first time a molecular mechanism in plants that reacts to temperature – often triggering the buds of spring we long to see at the end of winter.
4. With weather and temperatures set to become ever more unpredictable due to climate change, researchers say the discovery that this light-sensing molecule also functions as the internal thermometer in plant cells could help us breed tougher crops. ‘It is estimated that agricultural yields will need to double by 2050, but climate change is a major threat to achieving this. Key crops such as wheat and rice are sensitive to high temperatures. Thermal stress reduces crop yields by around 10% for every one degree increase in temperature,’ says lead researcher Dr Philip Wigge from Cambridge’s Sainsbury Laboratory. ‘Discovering the molecules that allow plants to sense temperature has the potential to accelerate the breeding of crops resilient to thermal stress and climate change.’
5. In their active state, phytochrome molecules bind themselves to DNA to restrict plant growth. During the day, sunlight activates the molecules, slowing down growth. If a plant finds itself in shade, phytochromes are quickly inactivated – enabling it to grow faster to find sunlight again. This is how plants compete to escape each other’s shade. ‘Light-driven changes to phytochrome activity occur very fast, in less than a second,’ says Wigge. At night, however, it’s a different story. Instead of a rapid deactivation following sundown, the molecules gradually change from their active to inactive state. This is called ‘dark reversion’. ‘Just as mercury rises in a thermometer, the rate at which phytochromes revert to their inactive state during the night is a direct measure of temperature,’ says Wigge.
6. ‘The lower the temperature, the slower the rate at which phytochromes revert to inactivity, so the molecules spend more time in their active, growth-suppressing state. This is why plants are slower to grow in winter. Warm temperatures accelerate dark reversion, so that phytochromes rapidly reach an inactive state and detach themselves from the plant’s DNA – allowing genes to be expressed and plant growth to resume.’ Wigge believes phytochrome thermo-sensing evolved at a later stage, and co-opted the biological network already used for light-based growth during the downtime of night.
7. Some plants mainly use day length as an indicator of the reason. Other species, such as daffodils, have considerable temperature sensitivity, and can flower months in advance during a warm winter. In fact, the discovery of the dual role of phytochromes provides the science behind a well-known rhyme long used to predict the coming season: oak before ash we’ll have a plash, ash before oak we’re in for a soak. Wigge explains: ‘Oak trees rely much more on temperature, likely using phytochromes as thermometers to dictate development, whereas ash trees rely on measuring day length to determine their seasonal timing. A warmer spring, and consequently a higher likeliness of a hot summer, will result in oak leafing before ash. A cold spring will see the opposite. As the British know only too well, a colder summer is likely to be a rain-soaked one.’
8. The new findings are the culmination of twelve years of research involving scientists from Germany, Argentina and the US, as well as the Cambridge team. The work was done in a model system, using a mustard plant called Arabidopsis, but Wigge says the phytochrome genes necessary for temperature sensing are found in crop plants as well. ‘Recent advances in plant genetics now mean that scientists are able to rapidly identify the genes controlling these processes in crop plants, and even alter their activity using precise molecular “scalpels”,’ adds Wigge. ‘Cambridge is uniquely well-positioned to do this kind of research as we have outstanding collaborators nearby who work on more applied aspects of plant biology, and can help us transfer this new knowledge into the field.’

Questions 1-6

1 The Cambridge scientists’ discovery of the ‘thermometer molecule’ caused surprise among other scientists.

2 The target for agricultural production by 2050 could be missed.

3 Wheat and rice suffer from a rise in temperatures.

4 It may be possible to develop crops that require less water.

5 Plants grow faster in sunlight than in shade.

6 Phytochromes change their state at the same speed day and night.

Questions 7-11

7 mention of specialists who can make use of the research findings

8 a reference to a potential benefit of the research findings

9 scientific support for a traditional saying

10 a reference to people traditionally making plans based on plant behaviour

11 a reference to where the research has been reported

Questions 12-14

12 Daffodils are likely to flower early in response to ……………………. weather.

13 If ash trees come into leaf before oak trees, the weather in ……………………. will probably be wet.

14 The research was carried out using a particular species of ……………………..

‘Plant Thermometer Trigger’ IELTS Reading Answers With Location and Explanation

Read further for the explanations and location of the ‘Plant Thermometer Trigger’ IELTS Reading answer

1 Answer: Not given

Question type: True/False/Not given

Answer Location: N.A

Answer explanation: The paragraph does not provide information on whether the Cambridge scientists’ discovery surprised other scientists. Hence the answer is not given.

2 Answer: True

Question type: True/False/Not given

Answer Location: Paragraph D, Line 3

Answer explanation: The paragraph mentions that agricultural yields need to double by 2050, but climate change is a threat to achieving this target. Hence, the answer is true.

3 Answer: True

Question type: True/False/Not given

Answer Location: Paragraph D, Line 4

Answer explanation: The paragraph states that key crops such as wheat and rice are sensitive to high temperatures, and thermal stress reduces crop yields with an increase in temperature. Hence, the answer is true.

4 Answer: Not given

Question type: True/False/Not given

Answer Location: N.A

Answer explanation: The paragraph does not provide information on developing crops that require less water. Hence, the answer is not given.

5 Answer: False

Question type: True/False/Not given

Answer Location: Paragraph E, Line 2

Answer explanation: The paragraph mentions that during the day, sunlight activates phytochrome molecules, slowing down plant growth, but it doesn’t state that plants grow faster in sunlight than in the shade. Hence the answer is false.

Tips for Answering the Question Types in the ‘Plant Thermometer Trigger’ IELTS Reading Passage

Let us check out some quick IELTS exam preparation tips to answer the types of questions in the ‘Plant Thermometer Trigger’ Reading passage.

True/False/Not Given: 

True/False/Not Given questions are a type of IELTS Reading question that requires you to identify whether a statement is true, false, or not given in the passage.

• True statements are statements that are explicitly stated in the passage.
• False statements are statements that are explicitly contradicted in the passage.
• Not Given statements are statements that are neither explicitly stated nor contradicted in the passage

To answer True/False/Not Given questions, you need to be able to understand the passage and identify the key information. You also need to be able to distinguish between statements that are explicitly stated, contradicted, and not given.

Matching Features: 

Matching Features is a type of IELTS reading question that requires you to match a list of features to the correct people, places, or things in a passage.

To answer matching features questions, you can use the following strategies:

• Read the features first hence this will give you an idea of the types of information that you are looking for in the passage.
• Read the passage quickly and this will give you a general understanding of the content of the passage.
• Match the features to the people, places, or things. As you read the passage, look for the information that matches each feature.
• Check your answers and once you have matched all of the features, double-check your answers to make sure that they are correct.

Sentence Completion:

Sentence Completion is a type of IELTS reading question that requires you to fill in a gap in a sentence with a word or phrase from the passage.

To answer these questions, you can use the following strategies:

• Read the sentence carefully hence this will give you an idea of the type of word or phrase that is missing.
• Scan the passage for the keywords. Hence, the keywords in the sentence can help you to identify the correct word or phrase.
• Read the sentence with the missing word or phrase. This will help you to see how the word or phrase fits into the sentence.
• Check your answer and once you have filled in the gap, make sure that your answer makes sense in the context of the sentence.

Great work on attempting to solve the ‘Plant Thermometer Trigger’ IELTS reading passage! To crack your IELTS Reading in the first go, try solving more of the reading passages.

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• IELTS Reading Tips and Techniques to Increase your Reading Speed
• How to Do Short Answer Type of Questions in IELTS Reading? | IELTSMaterial.com
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