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Câu hỏi: 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 36 to 42.
Fungi, of which there are over 100,000 species, including yeasts and other single-celled organisms as well as the common molds and mushrooms, were formerly classified as members of the plant kingdom. However, in reality they are very different from plants and today they are placed in a separate group altogether. The principal reason for this is that none of them possesses chlorophyll, and since they cannot synthesize their own carbohydrates, they obtain their supplies either from the breakdown of dead organic matter or from other living organisms. Furthermore the walls of fungal cells are not made of cellulose, as those of plants are, but of another complex sugar like polymer called chitin, the material from which the hard outer skeletons of shrimps, spiders, and insects are made. The difference between the chemical composition of the cell walls of fungi and those of plants is of enormous importance because it enables the tips of the growing hyphae, the threadlike cells of the fungus, to secrete enzymes that break down the walls of plant cells without having any effect on those of the fungus itself. It is these cellulose-destroying enzymes that enable fungi to attack anything made from wood, wood pulp, cotton, flax, or other plant material.
The destructive power of fungi is impressive. They are a major cause of structural damage to building timbers, a cause of disease in animals and humans, and one of the greatest causes of agricultural losses. Entire crops can be wiped out by fungal attacks both before and after harvesting. Some fungi can grow at +50°C, while others can grow at -5°c, so even food in cold storage may not be completely safe from them. On the other hand, fungi bring about the decomposition of dead organic matter, thus enriching the soil and returning carbon dioxide to the atmosphere. They also enter into a number of mutually beneficial relationships with plants and other organisms. In addition, fungi are the source of many of the most potent antibiotics used in clinical medicine, including penicillin.
The word "principal'' in paragraph 1 is closest in meaning to______________.
A. true
B. main
C. logical
D. obvious
Fungi, of which there are over 100,000 species, including yeasts and other single-celled organisms as well as the common molds and mushrooms, were formerly classified as members of the plant kingdom. However, in reality they are very different from plants and today they are placed in a separate group altogether. The principal reason for this is that none of them possesses chlorophyll, and since they cannot synthesize their own carbohydrates, they obtain their supplies either from the breakdown of dead organic matter or from other living organisms. Furthermore the walls of fungal cells are not made of cellulose, as those of plants are, but of another complex sugar like polymer called chitin, the material from which the hard outer skeletons of shrimps, spiders, and insects are made. The difference between the chemical composition of the cell walls of fungi and those of plants is of enormous importance because it enables the tips of the growing hyphae, the threadlike cells of the fungus, to secrete enzymes that break down the walls of plant cells without having any effect on those of the fungus itself. It is these cellulose-destroying enzymes that enable fungi to attack anything made from wood, wood pulp, cotton, flax, or other plant material.
The destructive power of fungi is impressive. They are a major cause of structural damage to building timbers, a cause of disease in animals and humans, and one of the greatest causes of agricultural losses. Entire crops can be wiped out by fungal attacks both before and after harvesting. Some fungi can grow at +50°C, while others can grow at -5°c, so even food in cold storage may not be completely safe from them. On the other hand, fungi bring about the decomposition of dead organic matter, thus enriching the soil and returning carbon dioxide to the atmosphere. They also enter into a number of mutually beneficial relationships with plants and other organisms. In addition, fungi are the source of many of the most potent antibiotics used in clinical medicine, including penicillin.
The word "principal'' in paragraph 1 is closest in meaning to______________.
A. true
B. main
C. logical
D. obvious
- principal ~ main (adj): chính
- true (adj): đúng, thực
- logical (adj): logic, hợp lý
- obvious (adj): rõ ràng
Thông tin trong bài: "However, in reality they are very different from plants and today they are placed in a separate group altogether. The principal reason for this is that none of them possesses chlorophyll..." (Tuy nhiên, trên thực tế chúng rất khác với thực vật và ngày nay chúng được xếp vào một nhóm tách biệt hoàn toàn. Lý do chính cho điều này là không loại nào trong số chúng có chất diệp lục...)
- true (adj): đúng, thực
- logical (adj): logic, hợp lý
- obvious (adj): rõ ràng
Thông tin trong bài: "However, in reality they are very different from plants and today they are placed in a separate group altogether. The principal reason for this is that none of them possesses chlorophyll..." (Tuy nhiên, trên thực tế chúng rất khác với thực vật và ngày nay chúng được xếp vào một nhóm tách biệt hoàn toàn. Lý do chính cho điều này là không loại nào trong số chúng có chất diệp lục...)
Đáp án B.