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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.The use of the phrase “come in handy” indicates that the process is ______

Xem chi tiết 1 K lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.It can be inferred from the passage, in the early spring, the buds of plants __________.

Xem chi tiết 1.7 K lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.What is the main topic of the passage?

Xem chi tiết 1.6 K lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions       About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.       The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.Which of the following best describes the organization of the passage?

Xem chi tiết 662 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! According to the passage, which of the following NOT true about the tradition of tooth giving in the West? 

Xem chi tiết 552 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! The word "origins" in paragraph 2 is closest in meaning to ________.

Xem chi tiết 645 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 8 to 12.      Different cultures follow their own special customs when a child's baby teeth fall out. In Korea, for example, they have the custom of throwing lost teeth up on the roof of a house. According to tradition, a magpie will come and take the tooth. Later, the magpie will return with a new tooth for the child. In other Asian countries, such as Japan and Vietnam, children follow a similar tradition of throwing their lost teeth onto the roofs of houses. Birds aren't the only animals thought to take lost teeth. In Mexico and Spain, tradition says a mouse takes a lost tooth and leaves some money. However, in Mongolia, dogs are responsible for taking teeth away.      Dogs are highly respected in Mongolian culture and are considered guardian angels of the people. Tradition says that the new tooth will grow good and strong if the baby tooth is fed to a guardian angel. Accordingly, parents in Mongolia will put their child's lost tooth in a piece of meat and feed it to a dog. The idea of giving lost teeth to an angel or fairy is also a tradition in the West. Many children in Western countries count on the Tooth Fairy to leave money or presents in exchange for a tooth. The exact origins of the Tooth Fairy are a mystery, although the story probably began in England or Ireland centuries ago. According to tradition, a child puts a lost tooth under his or her pillow before going to bed. In the wee hours, while the child is sleeping, the Tooth Fairy takes the tooth and leaves something else under the pillow. In France, the Tooth Fairy leaves a small gift. In the United States, however, the Tooth Fairy usually leaves money. These days, the rate is 1 USD to 5 USD per tooth, adding up to a lot of money from the Tooth Fairy! According to paragraph 2, parents in Mongolia feed their child's lost tooth to a dog because ________. 

Xem chi tiết 603 lượt xem 4 năm trước