五年级自然科学英语阅读理解20题

五年级自然科学英语阅读理解20题
1
<背景文章>
Plants are amazing organisms, and one of the most important processes they carry out is photosynthesis. Photosynthesis can be defined as the process by which green plants use sunlight, carbon dioxide, and water to produce glucose (a type of sugar) and oxygen.
The process of photosynthesis mainly takes place in the chloroplasts of plant cells. Chlorophyll, a pigment in the chloroplasts, absorbs sunlight. Then, plants take in carbon dioxide from the air through small pores called stomata on their leaves. At the same time, they absorb water from the soil through their roots. With the energy from sunlight, carbon dioxide and water are chemically combined to form glucose and oxygen. The glucose is used by the plants as a source of energy for growth, reproduction, and other life processes. The oxygen is released into the atmosphere.
The importance of photosynthesis to plants themselves is self - evident. It provides the energy and substances necessary for their growth and development. For the earth's ecosystem, photosynthesis is also crucial. It is the main source of oxygen in the atmosphere, which is essential for the survival of all aerobic organisms. In addition, photosynthesis also helps to regulate the carbon cycle on the earth by absorbing carbon dioxide.
What is photosynthesis?
A. The process by which plants use moonlight to produce something.
B. The process by which green plants use sunlight, carbon dioxide and water to produce glucose and oxygen.
C. The process by which plants only need water to grow.
D. The process by which plants produce carbon dioxide.
答案：B。

解析：文章明确提到Photosynthesis can be defined as the process by which green plants use sunlight, carbon dioxide, and water to produce glucose (a type of sugar) and oxygen，而A选项中的moonlight 错误，C选项只提到water过于片面，D选项说产生二氧化碳与原文相悖。

2. <问题2>
Where does the process of photosynthesis mainly take place?
A. In the roots of plants.
B. In the flowers of plants.
C. In the chloroplasts of plant cells.
D. In the stems of plants.
答案：C。

解析：原文提到The process of photosynthesis mainly takes place in the chloroplasts of plant cells，A选项roots是吸收水分的地方，B选项flowers不是光合作用主要发生地，D选项stems也不是光合作用主要场所。

What does chlorophyll do in photosynthesis?
A. It releases oxygen.
B. It absorbs sunlight.
C. It absorbs water.
D. It produces glucose.
答案：B。

解析：根据文中Chlorophyll, a pigment in the chloroplasts, absorbs sunlight可知，A选项释放氧气不是叶绿素的功能，C选项吸收水分是根部的功能，D选项产生葡萄糖是二氧化碳和水反应后的结果。

4. <问题4>
Why is photosynthesis important for plants?
A. It helps plants to look beautiful.
B. It provides the energy and substances necessary for their growth and development.
C. It makes plants produce more leaves.
D. It makes plants taller.
答案：B。

解析：文章明确指出The importance of photosynthesis to plants themselves is self - evident. It provides the energy and substances necessary for their growth and development，A选项使植物看起来漂亮不是光合作用对植物重要的原因，C选项产生更多叶子只是光合作用对植物影响的一个小方面，D选项使植物变高也是比较片面的。

What is one of the important roles of photosynthesis in the earth's ecosystem?
A. It makes the earth warmer.
B. It is the main source of oxygen in the atmosphere.
C. It makes the soil more fertile.
D. It makes the water cleaner.
答案：B。

解析：原文提到It is the main source of oxygen in the atmosphere, which is essential for the survival of all aerobic organisms，A选项使地球变暖不是光合作用在生态系统中的作用，C选项使土壤更肥沃不是光合作用的主要生态作用，D选项使水更清洁也不是光合作用的主要生态作用。

2
<背景文章>
A volcano is a fascinating and powerful natural phenomenon. V olcanoes are formed when magma, which is molten rock deep within the Earth, rises towards the surface. Magma is created by the extreme heat in the Earth's mantle. As the magma rises, it collects in magma chambers beneath the Earth's crust. When the pressure in the magma chamber becomes too great, the magma forces its way up through cracks and fissures in the crust, leading to a volcanic eruption.
During a volcanic eruption, various substances are ejected from the
volcano. Lava, which is the magma that has reached the surface, flows out of the volcano. It can be extremely hot and move slowly or quickly depending on its viscosity. Ash, rocks, and gases are also expelled during an eruption. The ash can spread over large areas, covering the surrounding land, plants, and buildings.
The impact on the surrounding environment can be significant. The lava can destroy everything in its path, burning down forests and covering fields. The ash can make it difficult for plants to grow as it may block sunlight and contaminate the soil. However, in the long term, volcanic soil is very fertile because it contains many minerals.
The geological structure in volcanic areas is unique. There are often volcanic cones, which are the mounds formed by the accumulation of lava and volcanic debris. There may also be calderas, which are large depressions formed when a volcano collapses after a major eruption.
6. What is magma?
A. Molten rock on the Earth's surface.
B. Molten rock deep within the Earth.
C. Solid rock in the Earth's crust.
D. Gaseous substance in the Earth's mantle.
答案：B。

解析：文章明确提到“V olcanoes are formed when magma, which is molten rock deep within the Earth”，即岩浆是地球深处的熔融岩石，所以答案为B。

7. What causes magma to rise towards the surface?
A. The cold temperature in the mantle.
B. The low pressure in the magma chamber.
C. The extreme heat in the mantle.
D. The strong wind on the surface.
答案：C。

解析：根据原文“Magma is created by the extreme heat in the Earth's mantle. As the magma rises...”可知是地幔中的高温使得岩浆上升，所以选C。

8. What is not ejected during a volcanic eruption?
A. Lava.
B. Ice.
C. Ash.
D. Gases.
答案：B。

解析：文章提到在火山爆发期间会喷出熔岩、火山灰和气体，并没有提到冰，所以答案是B。

9. Why can volcanic soil be very fertile?
A. Because it is covered with ash.
B. Because it has a lot of sunlight.
C. Because it contains many minerals.
D. Because it is very wet.
答案：C。

解析：文中提到“in the long term, volcanic soil is very fertile because it contains many minerals”，火山土壤肥沃是因为含有很
多矿物质，所以选C。

10. What is a caldera?
A. A mound formed by lava and debris.
B. A small hill near the volcano.
C. A large depression formed after a major eruption.
D. A crack in the Earth's crust.
答案：C。

解析：文章最后提到“calderas, which are large depressions formed when a volcano collapses after a major eruption”，所以答案为C。

3
<背景文章>
Wind is an important part of nature. It is formed due to the unequal heating of the Earth's surface. The sun heats the Earth unevenly. For example, the land heats up and cools down more quickly than the ocean. When the air above the warm areas rises, cooler air from the surrounding areas moves in to take its place. This movement of air is what we call wind.
There are different types of winds. Monsoon winds are very well - known. Monsoons are seasonal winds. In many Asian countries, the summer monsoon brings heavy rainfall which is crucial for agriculture. The winter monsoon is usually drier. Another type is the trade winds. These are steady winds that blow towards the equator. They have had a great influence on the history of navigation and trade.
Wind also has a significant impact on climate. It helps in distributing
heat around the world. In areas where there are strong winds, it can affect human activities. For example, strong winds can make it difficult for ships to sail safely. Wind can also be used as a source of energy. Wind turbines are used to generate electricity in many places.
11. What is the main cause of wind formation?
A. The rotation of the Earth.
B. The unequal heating of the Earth's surface.
C. The movement of the ocean currents.
D. The gravitational pull of the moon.
答案：B。

解析：文章明确提到“Wind is formed due to the unequal heating of the Earth's surface.”，即风是由于地球表面受热不均而形成的，而不是地球自转、洋流运动或者月球引力，所以答案是B。

12. Which of the following statements about monsoon winds is true?
A. Monsoon winds blow all year round.
B. The summer monsoon is always dry.
C. The winter monsoon brings heavy rain.
D. Monsoon winds are seasonal winds.
答案：D。

解析：文章中提到“Monsoons are seasonal winds.”，说明季风是季节性的风，A选项说季风全年都吹是错误的；文中说夏季季风带来大量降雨，所以B选项错误；冬季季风比较干燥，C选项错误，故答案为D。

13. What is the importance of trade winds in history?
A. They caused floods.
B. They were important for navigation and trade.
C. They destroyed many ships.
D. They made the climate very cold.
答案：B。

解析：根据文章“These are steady winds that blow towards the equator. They have had a great influence on the history of navigation and trade.”可知，信风对航海和贸易历史有很大影响，而不是造成洪水、破坏很多船或者使气候寒冷，所以答案是B。

14. How does wind affect climate?
A. It makes the climate very dry.
B. It helps in distributing heat around the world.
C. It only cools the climate.
D. It has no effect on climate.
答案：B。

解析：文章提到“Wind also has a significant impact on climate. It helps in distributing heat around the world.”，说明风有助于在全球范围内分配热量，而不是使气候干燥、只冷却气候或者对气候没有影响，所以答案是B。

15. Which of the following can be a negative impact of strong winds on human activities?
A. It helps generate electricity.
B. It makes it difficult for ships to sail safely.
C. It brings rain for agriculture.
D. It is good for wind - surfing.
答案：B。

解析：文章提到“In areas where there are strong winds, it can affect human activities. For example, strong winds can make it difficult for ships to sail safely.”，强风会使船只难以安全航行，这是强风对人类活动的负面影响，而A选项是风的积极作用，C选项虽然提到风对农业的影响但不是强风的负面影响，D选项也是风的积极作用，所以答案是B。

4
<背景文章>
The water cycle is a very important process on Earth. It involves several key steps. First, evaporation occurs. The sun heats up water in oceans, lakes, and rivers, and turns it into water vapor. This water vapor rises into the atmosphere. Then, condensation takes place. As the water vapor rises, it cools down and turns back into tiny water droplets. These droplets gather together to form clouds. Next is precipitation. When the clouds become heavy enough, the water droplets fall back to the Earth as rain, snow, sleet or hail. After that, runoff happens. The water that falls on land may run off into rivers, lakes or oceans, or it may seep into the ground to become groundwater. The water cycle is crucial for the distribution of water resources on Earth. It ensures that water is constantly being recycled and redistributed, so that different parts of the Earth can have the water they need.
16. What is the first step in the water cycle?
A. Condensation
B. Evaporation
C. Precipitation
D. Runoff
答案：B。

解析：文章明确提到在水循环中，首先发生的是蒸发（evaporation），太阳使海洋、湖泊和河流中的水受热变成水蒸气，然后才是其他步骤，所以第一个步骤是蒸发，选B。

17. What makes water vapor rise into the atmosphere?
A. The wind
B. The heat from the sun
C. Gravity
D. The clouds
答案：B。

解析：根据文章，是太阳的热量（The sun heats up water...and turns it into water vapor. This water vapor rises into the atmosphere）使水变成水蒸气并上升到大气中，而不是风、重力或者云，所以选B。

18. When water vapor cools down in the atmosphere, it turns into _.
A. ice
B. large water droplets
C. tiny water droplets
D. steam
答案：C。

解析：文章提到当水蒸气在大气中冷却时，会变成小水滴（（As the water vapor rises, it cools down and turns back into tiny water droplets），而不是冰、大水滴或者蒸汽，所以选C。

19. Which of the following is a form of precipitation?
A. Fog
B. Dew
C. Rain
D. Mist
答案：C。

解析：文章中提到降水（precipitation）的形式有雨、雪、雨夹雪或者冰雹（the water droplets fall back to the Earth as rain, snow, sleet or hail），在选项中只有雨（（Rain）是降水的一种形式，雾、露水和薄雾都不是，所以选C。

20. Why is the water cycle important for the Earth?
A. It makes the Earth cooler.
B. It creates more clouds.
C. It distributes water resources.
D. It makes water disappear.
答案：C。

解析：文章最后提到水循环对地球水资源的分布至关重要（The water cycle is crucial for the distribution of water resources on Earth），它确保水不断被循环和重新分配，而不是使地球变凉、创造更多云或者让水消失，所以选C。