Tính trạng nhóm máu của người do 3 alen qui định. Ở một quần thể đang cân bằng về mặt di truyền, trong đó I^A = 0,5; I^B = 0,2; I^O = 0,3. Có mấy kết luận chính xác?

(1) Người có nhóm máu AB chiếm tỉ lệ 10%.

(2) Người nhóm máu O chiếm tỉ lệ 9%.

(3) Có 3 kiểu gen đồng hợp về tính trạng nhóm máu.

(4) Người nhóm máu A chiếm tỉ lệ 35%.

(5) Trong số những người có nhóm máu A, người đồng hợp chiếm tỉ lệ 5/11.

A. 2.

B. 3.

C. 5.

D. 4.

Cho các phát biểu sau:

(a) Ở nhiệt độ thường, Cu ( OH ) 2  tan được trong dung dịch glixerol.

(b) Ở nhiệt độ thường, C 2 H 4 phản ứng được với nước brom.

(c) Đốt cháy hoàn toàn CH 3 COOCH 3 ₃ thu được số mol CO 2 bằng số mol H 2 O .

(d) Glyxin H 2 NCH 2 COOH phản ứng được với dung dịch NaOH.

Số phát biểu đúng là

A. 3

B. 4

C. 1

D. 2

Nung nóng hỗn hợp X gồm 0,2 mol vinylaxetilen và 0,2 mol  H 2 với xúc tác Ni, thu được hỗn hợp Y có tỉ khối hơi so với  H 2  là 21,6. Hỗn hợp Y làm mất màu tối đa m gam brom trong C C l 4 . Giá trị của m là:

A. 80

B. 72

C. 30

D. 45

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.

        The cause of tooth decay is acid, which is produced by bacteria in the mouth. The acid removes minerals from tooth enamel, allowing tooth decay to begin; the saliva in your mouth encourages remineralization and neutralizes the acid. The rate at which bacteria in the mouth produce acid depends on the amount of plaque on the teeth, the composition of the microbial flora, and whether the bacteria of the plaque have been "primed" by frequent exposure to sugar. To keep your teeth healthy, a regular dental hygiene program should be followed.
        Removing plaque with a toothbrush and dental floss temporarily reduces the numbers of bacteria in the mouth and thus reduces tooth decay. It also makes the surfaces of the teeth more accessible, enabling saliva to neutralize acid and remineralize lesions. If fluoride is present in drinking water when teeth are forming, some fluoride is incorporated into the enamel of the teeth, making them more resistant to attack by acid. Fluoride toothpaste seems to act in another way, by promoting the remineralization of early carious lesions.
In addition to a regular dental hygiene program, a good way to keep your teeth healthy is to reduce your intake of sweet food. The least cavity-causing way to eat sweets is to have them with meals and not between. The number of times you eat sweets rather than the total amount determines how much harmful acid the bacteria in your saliva produce. But the amount of sweets influences the quality of your saliva. Avoid, if you can, sticky sweets that stay in your mouth a long time. Also try to brush and floss your teeth after eating sugary foods. Even rinsing your mouth with water is effective. Whenever possible, eat foods with fiber, such as raw carrot sticks, apples, celery sticks, etc., that scrape off plaque, acting as a toothbrush. Cavities can be greatly reduced if these rules are followed when eating sweets.

The author of the passage states that the amount of acid produced by the bacteria in your saliva increases __________.

A. with the amount of sweets you eat

B. with the number of times you eat sweets 

C. if you eat sweets with your meals   

D. if you eat sticky sweet

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrases that best fits each of the numbered blanks.

Most Americans eat three meals (10) ______ the day: breakfast, lunch, and dinner. Breakfast begins between 7:00 and 8:00am, lunch between 11:00 am and noon, and dinner between 6:00 and 8:00 pm. On Sundays "brunch" is a (11) ______ of breakfast and lunch, typically beginning at 11:00 am. Students often enjoy a "study break" or evening snack around 10:00 or 11:00 pm. Breakfast and lunch tend to be light meals, with only one course.

Dinner is the main meal.

For breakfast Americans will eat cereal with milk which are often mixed (12) ______ in a bowl, a glass of orange juice, and toasted bread or muffin with jam, butter, or margarine. Another common breakfast meal is scrambled eggs or an omelet with potatoes and breakfast meat (bacon or sausage). People who are on a diet eat just a cup of yogurt.

Lunch and dinner are more (13) ______. When eating at a formal dinner, you may be overwhelmed by the number of utensils. How do you (14) ______ the difference between a salad fork, a butter fork, and a dessert fork? Most Americans do not know the answer. But knowing which fork or spoon to use first is simple: use the outermost utensils first and the utensils closest to the plate last.

Điền ô số 12

A. each other

B. together

C. one another

D. others

Thể tích H₂ (0ºC và 2atm) vừa đủ để tác dụng với 11,2 gam anđehit acrylic là

A. 4,48 lít

B. 2,24 lít

C. 0,448 lít

D. 0,336 lít

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

I think it’s (A) importance for us (B) to find solutions (C) to (D) our problem.

A. importance 

B. to find

C. to 

D. our problem.

Hầu hết các bệnh di truyền phân tử ở người là do đột biến gen gây nên. Có mấy lí do dưới đây dùng để giải thích nguyên nhân gây bệnh của gen đột biến?

(1) gen đột biến hoàn toàn không tổng hợp được prôtêin.

(2) gen đột biến tổng hợp ra prôtêin bị biến đổi về chức năng.

(3) gen đột biến tổng hợp số lượng prôtêin quá nhiều.

(4) gen đột biến tổng hợp số lượng prôtêin quá ít.

A. 3

B. 1

C. 4

D. 2

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 following questions.

Although they are an inexpensive supplier of vitamins, minerals, and high-quality protein, eggs also contain a high level of blood cholesterol, one of the major causes of heart diseases. One egg yolk, in fact, contains a little more than two-thirds of the suggested daily cholesterol limit. This knowledge has driven egg sales to plummet in recent years, which in turn has brought about the development of several alternatives to eating regular eggs. One alternative is to eat substitute eggs. These egg substitutes are not really eggs, but they look somewhat like eggs when they are cooked. They have the advantage of having low cholesterol rates, and they can be scrambled or used in baking. One disadvantage, however, is that they are not good for frying, poaching, or boiling. A second alternative to regular eggs is a new type of egg, sometimes called 'designer' eggs. These eggs are produced by hens that are fed low-flat diets consisting of ingredients such as canola oil, flax, and rice bran. In spite of their diet, however, these hens produce eggs that contain the same amount of cholesterol as regular eggs. Yet, the producers of these eggs claim that eating their eggs will not raise the blood cholesterol in humans.

         Egg producers claim that their product has been portrayed unfairly. They cite scientific studies to back up their claim. And, in fact, studies on the relationship between eggs and human cholesterol levels have brought mixed result. It may be that it is not the type of eggs that is the main determinant of cholesterol but the person who is eating the eggs. Some people may be more sensitive to cholesterol derived from food than other people. In fact, there is evidence that certain dietary fats stimulate the body's production of blood cholesterol. Consequently, while it still makes sense to limit one's intake of eggs, even designer eggs, it seems that doing this without regulating dietary fat will probably not help reduce the blood cholesterol level.

What is meant by the phrase 'mixed result'?

A. The result are blended   

B. The result are a composite of things

C. The result are inconclusive  

D. The result are mingled togethe