Cho các ví dụ sau:

1. Gieo ngải ở mật độ 100.000 hạt trên 1m² thì giữa những cây con có một sự cạnh tranh mạnh mẽ, nhiều cây bị chết, mật độ quần thể giảm đi rõ rệt.

2. Mọt bột cấy trong môi trường nuôi cấy có 64g bột thì số lượng cá thể đạt ở mức cực đại là 1750 cá thể. Nếu môi trường chỉ có 16g bột thì số lượng cá thể tối đa chỉ đạt được 650 cá thể.

Các ví dụ trên đề cập đến hiện tượng sinh thái nào?

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:

                                                        ACADEMICS AREN’T THE PROBLEM

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras.

Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago.

The data show that full-time students in all types of colleges study much less now than they did a generation ago - a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be.

The time-use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. And though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly.

In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure.
   

Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately.

In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer, would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.

Question: Students nowadays seem to be studying less and _______.             

Read the following passage and mark the letters A, B, C or D on your answer sheet to indicate the correct answer to each of the questions: 

The biologist's role in society as well as his moral and ethical responsibility in the discovery and development of new ideas has led to a reassessment of his social and scientific value systems. A scientist can no longer ignore the consequences of his discoveries; he is as concerned with the possible misuses of his findings as he is with the basic research in which he is involved. This emerging social and political role of the biologist and all other scientists requires a weighing of values that cannot be done with the accuracy or the objectivity of a laboratory balance. As a member of society, it is necessary for a biologist now to redefine his social obligations and his functions, particularly in the realm of making judgments about such ethical problems as man's control of his environment or his manipulation of genes to direct further evolutionary development.

Probably the greatest biological problem of the future, as it is of the present, will be to find ways to curb environmental pollution without interfering with man's constant effort to improve the quality of his life. Many scientists believe that underlying the spectre of pollution is the problem of surplus human population. A rise in population necessitates an increase in the operations of modern industry, the waste products of which increase the pollution of air, water, and soil. The question of how many people the resources of the Earth can support is one of critical importance.

Question: What is probably the most important biological problem mentioned in the passage?         

Read the following passage and mark the letters A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:

Scientists do not yet thoroughly understand just how the body of an individual becomes sensitive to a substance that is harmless or even wholesome for the average person. Milk, wheat, and egg, for example, rank among the most healthful and widely used foods. Yet these foods can cause persons sensitive to them to suffer greatly. At first, the body of the individual is not harmed by coming into contact with the substance. After a varying interval of time, usually longer than a few weeks, the body becomes sensitive to it, and an allergy has begun to develop. Sometimes it's hard to figure out if you have a food allergy, since it can show up so many different ways. Your symptoms could be caused by many other problems. You may have rashes, hives, joint pains, mimicking arthritis, headaches, irritability, or depression. The most common food allergies are to milk, eggs, seafood, wheat, nuts, seeds, chocolate, oranges, and tomatoes. Many of these allergies will not develop if these foods are not fed to an infant until her or his intestines mature at around seven months. Breast milk also tends to be protective. Migraines can be set off by foods containing tyramine, phenathylamine, monosodium glutamate, or sodium nitrate. Common foods which contain these are chocolate, aged cheeses, sour cream, red wine, pickled herring, chicken livers, avocados, ripe bananas, cured meats, many Oriental and prepared foods (read the labels!). Some people have been successful in treating their migraines with supplements of B-vitamins, particularly B6 and niacin. Children who are hyperactive may benefit from eliminating food additives, especially colorings, and foods high in salicylates from their diets. A few of these are almonds, green peppers, peaches, tea, grapes. This is the diet made popular by Benjamin Feingold, who has written the book “Why your Child is Hyperactive”. Other researchers have had mixed results when testing whether the diet is effective.

 Question 37: According to the passage, the difficulty in diagnosing allergies to foods is due to ______________.  

Read the following passage on climate change, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

The American type of football was developed in the 19th century from soccer and rugby football. Played by professionals, amateurs, college and high school students, or young children, football in American is one of the most popular sports besides basketball and baseball. It attracts millions of fans each fall and people are very supportive of their favourite teams. The football playing field of today is rectangular in shape and measures 100 yards long and 53.5 yards wide. White lines are painted on the playing field to mark off the distances to the end zone. The games is divided into four quarters, each fifteen minutes long. The first two quarters are known as the first half. There is a rest period between two halves which usually last about fifteen minutes. Each team has eleven players. Each team has offensive players who play when the team has possession of the ball and defensive players who play when the other team has the possession of the ball. Because of the body contact players have during the game, helmets are worn to protect their head and face area, whereas pads are worn to protect the shoulders, arms, and legs. Also, there are officials carrying whistles and flags to make certain that  the rules of the game are followed during the game. The football is made of leather and is brown in colour. It is shaped much like an oval and has white rings near each end of the football. These rings help the players see the ball when it is thrown or someone is running with it. The eight stitches on the top of the football help the  players to grip the ball when throwing or passing. The most famous game of the year is Super Bowl that is played in January or February. It is televised around the world and is watched by millions of people each year.

Question: When is the most famous football game held annually?         

Read the following passage on climate change, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

The American type of football was developed in the 19th century from soccer and rugby football. Played by professionals, amateurs, college and high school students, or young children, football in American is one of the most popular sports besides basketball and baseball. It attracts millions of fans each fall and people are very supportive of their favourite teams. The football playing field of today is rectangular in shape and measures 100 yards long and 53.5 yards wide. White lines are painted on the playing field to mark off the distances to the end zone. The games is divided into four quarters, each fifteen minutes long. The first two quarters are known as the first half. There is a rest period between two halves which usually last about fifteen minutes. Each team has eleven players. Each team has offensive players who play when the team has possession of the ball and defensive players who play when the other team has the possession of the ball. Because of the body contact players have during the game, helmets are worn to protect their head and face area, whereas pads are worn to protect the shoulders, arms, and legs. Also, there are officials carrying whistles and flags to make certain that  the rules of the game are followed during the game. The football is made of leather and is brown in colour. It is shaped much like an oval and has white rings near each end of the football. These rings help the players see the ball when it is thrown or someone is running with it. The eight stitches on the top of the football help the  players to grip the ball when throwing or passing. The most famous game of the year is Super Bowl that is played in January or February. It is televised around the world and is watched by millions of people each year.

Question: Why are there white rings on each end of the football?         

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:

Learning means acquiring knowledge or developing the ability to perform new behaviors. It is common to think of learning as something that takes place in school, but much of human learning occurs outside the classroom, and people continue to learn throughout their lives. Even before they enter school, young children learn to walk, to talk, and to use their hands to manipulate toys, food, and other objects. They use all of their senses to learn about the sights, sounds, tastes, and smells in their environments. They learn how to interact with their parents, siblings, friends, and other people important to their world. When they enter school, children learn basic academic subjects such as reading, writing, and mathematics. They also continue to learn a great deal outside the classroom. They learn which behaviors are likely to be rewarded and which are likely to be punished. They learn social skills for interacting with other children. After they finish school, people must learn to adapt to the many major changes that affect their lives, such as getting married, raising children, and finding and keeping a job. Because learning continues throughout our lives and affects almost everything we do, the study of learning is important in many different fields. Teachers need to understand the best ways to educate children. Psychologists, social workers, criminologists, and other human-service workers need to understand how certain experiences change people’s behaviors. Employers, politicians, and advertisers make use of the principles of learning to influence the behavior of workers, voters, and consumers. Learning is closely related to memory, which is the storage of information in the brain. Psychologists who study memory are interested in how the brain stores knowledge, where this storage takes place, and how the brain later retrieves knowledge when we need it. In contrast, psychologists who study learning are more interested in behavior and how behavior changes as a result of a person’s experiences. There arc many forms of learning, ranging from simple to complex. Simple forms of learning involve a single stimulus. A stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch, or taste. In a form of learning known as classical conditioning, people learn to associate two stimulus that occur in sequence, such as lightning followed by thunder. In operant conditioning, people learn by forming an association between a behavior and its consequences (reward or punishment). People and animals can also learn by observation - that is, by watching others perform behaviors. More complex forms of learning include learning languages, concepts, and motor skills.

Question: Getting married, raising children, and finding and keeping a job are mentioned in paragrapli 2 as examples of ________.  

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:

Learning means acquiring knowledge or developing the ability to perform new behaviors. It is common to think of learning as something that takes place in school, but much of human learning occurs outside the classroom, and people continue to learn throughout their lives. Even before they enter school, young children learn to walk, to talk, and to use their hands to manipulate toys, food, and other objects. They use all of their senses to learn about the sights, sounds, tastes, and smells in their environments. They learn how to interact with their parents, siblings, friends, and other people important to their world. When they enter school, children learn basic academic subjects such as reading, writing, and mathematics. They also continue to learn a great deal outside the classroom. They learn which behaviors are likely to be rewarded and which are likely to be punished. They learn social skills for interacting with other children. After they finish school, people must learn to adapt to the many major changes that affect their lives, such as getting married, raising children, and finding and keeping a job. Because learning continues throughout our lives and affects almost everything we do, the study of learning is important in many different fields. Teachers need to understand the best ways to educate children. Psychologists, social workers, criminologists, and other human-service workers need to understand how certain experiences change people’s behaviors. Employers, politicians, and advertisers make use of the principles of learning to influence the behavior of workers, voters, and consumers. Learning is closely related to memory, which is the storage of information in the brain. Psychologists who study memory are interested in how the brain stores knowledge, where this storage takes place, and how the brain later retrieves knowledge when we need it. In contrast, psychologists who study learning are more interested in behavior and how behavior changes as a result of a person’s experiences. There arc many forms of learning, ranging from simple to complex. Simple forms of learning involve a single stimulus. A stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch, or taste. In a form of learning known as classical conditioning, people learn to associate two stimulus that occur in sequence, such as lightning followed by thunder. In operant conditioning, people learn by forming an association between a behavior and its consequences (reward or punishment). People and animals can also learn by observation - that is, by watching others perform behaviors. More complex forms of learning include learning languages, concepts, and motor skills.  

Question: According to the passage, what are children NOT usually taught outside the classroom?         

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:

Learning means acquiring knowledge or developing the ability to perform new behaviors. It is common to think of learning as something that takes place in school, but much of human learning occurs outside the classroom, and people continue to learn throughout their lives. Even before they enter school, young children learn to walk, to talk, and to use their hands to manipulate toys, food, and other objects. They use all of their senses to learn about the sights, sounds, tastes, and smells in their environments. They learn how to interact with their parents, siblings, friends, and other people important to their world. When they enter school, children learn basic academic subjects such as reading, writing, and mathematics. They also continue to learn a great deal outside the classroom. They learn which behaviors are likely to be rewarded and which are likely to be punished. They learn social skills for interacting with other children. After they finish school, people must learn to adapt to the many major changes that affect their lives, such as getting married, raising children, and finding and keeping a job. Because learning continues throughout our lives and affects almost everything we do, the study of learning is important in many different fields. Teachers need to understand the best ways to educate children. Psychologists, social workers, criminologists, and other human-service workers need to understand how certain experiences change people’s behaviors. Employers, politicians, and advertisers make use of the principles of learning to influence the behavior of workers, voters, and consumers. Learning is closely related to memory, which is the storage of information in the brain. Psychologists who study memory are interested in how the brain stores knowledge, where this storage takes place, and how the brain later retrieves knowledge when we need it. In contrast, psychologists who study learning are more interested in behavior and how behavior changes as a result of a person’s experiences. There arc many forms of learning, ranging from simple to complex. Simple forms of learning involve a single stimulus. A stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch, or taste. In a form of learning known as classical conditioning, people learn to associate two stimulus that occur in sequence, such as lightning followed by thunder. In operant conditioning, people learn by forming an association between a behavior and its consequences (reward or punishment). People and animals can also learn by observation - that is, by watching others perform behaviors. More complex forms of learning include learning languages, concepts, and motor skills.  

Question: According to the passage, the study of learning is important in many fields due to ________.         

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:

Learning means acquiring knowledge or developing the ability to perform new behaviors. It is common to think of learning as something that takes place in school, but much of human learning occurs outside the classroom, and people continue to learn throughout their lives. Even before they enter school, young children learn to walk, to talk, and to use their hands to manipulate toys, food, and other objects. They use all of their senses to learn about the sights, sounds, tastes, and smells in their environments. They learn how to interact with their parents, siblings, friends, and other people important to their world. When they enter school, children learn basic academic subjects such as reading, writing, and mathematics. They also continue to learn a great deal outside the classroom. They learn which behaviors are likely to be rewarded and which are likely to be punished. They learn social skills for interacting with other children. After they finish school, people must learn to adapt to the many major changes that affect their lives, such as getting married, raising children, and finding and keeping a job. Because learning continues throughout our lives and affects almost everything we do, the study of learning is important in many different fields. Teachers need to understand the best ways to educate children. Psychologists, social workers, criminologists, and other human-service workers need to understand how certain experiences change people’s behaviors. Employers, politicians, and advertisers make use of the principles of learning to influence the behavior of workers, voters, and consumers. Learning is closely related to memory, which is the storage of information in the brain. Psychologists who study memory are interested in how the brain stores knowledge, where this storage takes place, and how the brain later retrieves knowledge when we need it. In contrast, psychologists who study learning are more interested in behavior and how behavior changes as a result of a person’s experiences. There arc many forms of learning, ranging from simple to complex. Simple forms of learning involve a single stimulus. A stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch, or taste. In a form of learning known as classical conditioning, people learn to associate two stimulus that occur in sequence, such as lightning followed by thunder. In operant conditioning, people learn by forming an association between a behavior and its consequences (reward or punishment). People and animals can also learn by observation - that is, by watching others perform behaviors. More complex forms of learning include learning languages, concepts, and motor skills.  

Question: Which of the following can be inferred about the learning process from the passage?         

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:

Learning means acquiring knowledge or developing the ability to perform new behaviors. It is common to think of learning as something that takes place in school, but much of human learning occurs outside the classroom, and people continue to learn throughout their lives. Even before they enter school, young children learn to walk, to talk, and to use their hands to manipulate toys, food, and other objects. They use all of their senses to learn about the sights, sounds, tastes, and smells in their environments. They learn how to interact with their parents, siblings, friends, and other people important to their world. When they enter school, children learn basic academic subjects such as reading, writing, and mathematics. They also continue to learn a great deal outside the classroom. They learn which behaviors are likely to be rewarded and which are likely to be punished. They learn social skills for interacting with other children. After they finish school, people must learn to adapt to the many major changes that affect their lives, such as getting married, raising children, and finding and keeping a job. Because learning continues throughout our lives and affects almost everything we do, the study of learning is important in many different fields. Teachers need to understand the best ways to educate children. Psychologists, social workers, criminologists, and other human-service workers need to understand how certain experiences change people’s behaviors. Employers, politicians, and advertisers make use of the principles of learning to influence the behavior of workers, voters, and consumers. Learning is closely related to memory, which is the storage of information in the brain. Psychologists who study memory are interested in how the brain stores knowledge, where this storage takes place, and how the brain later retrieves knowledge when we need it. In contrast, psychologists who study learning are more interested in behavior and how behavior changes as a result of a person’s experiences. There arc many forms of learning, ranging from simple to complex. Simple forms of learning involve a single stimulus. A stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch, or taste. In a form of learning known as classical conditioning, people learn to associate two stimulus that occur in sequence, such as lightning followed by thunder. In operant conditioning, people learn by forming an association between a behavior and its consequences (reward or punishment). People and animals can also learn by observation - that is, by watching others perform behaviors. More complex forms of learning include learning languages, concepts, and motor skills.  

Question: Which of the following statements is NOT true according to the passage?