Ở một loài thực vật. bộ nhiễm sắc thể lưỡng bội là 2n = 20. Một hợp tử đột biến của loài này tiến hành nguyên phân liên tiếp 4 lần đã cần môi trường cung cấp nguyên liệu tương đương 330 nhiễm sắc thể. Theo lí thuyết, hợp tử đột biến này có thể được hình thành do sự kết hợp giữa.

(1) giao tử n+1 với giao tử n+1.               

(2) giao tử n+1 với giao tử n.

(3) giao tử n+1 với giao tử n.

(4) giao tử n-1 với giao tử n-1.

A. 4

B. 2.

C. 3.

D. 1

Khi nói về tính hướng động của rễ cây, phát biểu nào sau đây đúng?

A. Rễ cây có tính hướng đất âm, hướng sáng dương

B. Rễ cây có tính hướng đất dương, hướng sáng âm

C. Rễ cây có tính hướng đất âm, hướng sáng âm

D. Rễ cây có tính hướng đất dương, hướng sáng dương

Hợp chất nào sau đây vừa tác dụng với dung dịch HCl, vừa tác dụng với dung dịch NaOH?

A. Cr(OH)₂.          

B. Fe(OH)₃. 

C. Mg(OH)₂.         

D. Cr(OH)₃.

Quan sát hình hộp chữ nhật ở hình 77:

- AB có song song với A’B’ hay không ? Vì sao ?

- AB có nằm trong mặt phẳng (A’B’C’D’) hay không ?

Việc phân chia số bữa ăn trong ngày có ảnh hưởng gì đến việc tổ chức ăn uống hợp lí?

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

Question 15: The President expressed his deep ______ over the bombing deaths.

A. grief

B. sorrow

C. sadness

D. all are correct

Cho các phát biểu sau:

(1) Phenol tan vô hạn trong nước ở 66^oC.

(2) Phenol có lực axit mạnh hơn ancol etylic.

(3) Phản ứng thế vào benzen dễ hơn phản ứng thế vào nhân thơm của phenol.

(4) Phenol tan tốt trong etanol.

(5) Phenol làm quỳ tím hóa đỏ.

(6) Nhóm OH phenol không bị thế bởi gốc axit như nhóm OH ancol.

Có bao nhiêu phát biểu đúng ?

A. 5

B. 4

C. 3

D. 6

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.

Are organically grown foods the best food choices? The advantages claimed for such foods over conventionally grown and marketed food products are now being debated. Advocates of organic foods – a term whose meaning varies greatly – frequently proclaim that such products are safer and more nutritious than others.

The growing interest of consumers in the safety and more nutritional quality of the typical North American diet is a welcome development. However, much of this interest has been sparked by sweeping claims that the food supply is unsafe or inadequate in meeting nutritional needs. Although most of these claims are not supported by scientific evidence, the preponderance of written material advancing such claims makes it difficult for the general public to separate fact from fiction. As a result, claims that eating a diet consisting entirely of organically grown foods prevents or cures disease or provides other benefits to health have become widely publicized and form the basis for folklore.

Almost daily the public is besieged by claims for “no-aging” diets, new vitamins, and other wonder foods. There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that untreated grains are better than fumigated grains and the like.

One thing that most organically grown food products seem to have in common is that they cost more than conventionally grown foods. But in many cases consumers are misled if they believe organic foods can maintain health and provide better nutritional quality than conventionally grown foods. So there is real cause for concern if consumers, particularly those with limited incomes, distrust the regular food and buy only expensive organic foods instead.

The “welcome development” is an increase in _______.

A. interest in food safety and nutritional quality of the typical North American diet

B. the nutritional quality of the typical North American diet

C. the amount of healthy food grown in North America

D. the number of consumers in North America

Read the following passage and mark the letter A, B, C or D to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35.

GETTING TO THE ROOT OF BONSAI CRIME

Bonsai trees have always been a source of great fascination to people. They are perfect miniatures, grown in pots small enough to sit on a windowsill. You have to keep reminding yourself that these frees are actually real and identical to their larger cousins in all (31) ______except their size. Rather like other small and perfectly-formed artifacts, bonsai trees command quite a high price in the marketplace and so it doesn't come as a great surprise to find that they also (32) ______the attention of thieves. It seems that quite a flourishing business has evolved, in which they are stolen from the homes of growers and collectors, then repotted and trimmed by unscrupulous dealers, to be sold on, at good prices, to (33) ______buyers.

One of Britain's top collectors of bonsai trees, Paul Widdington, believes that he has found a solution, however. After losing his life's work, valued at £250,000, when burglars broke into his home one night, Paul decided to (34) ______the possibilities of electronically tagging the trees he bought as a replacement. This involves injecting a microchip the size of a grain of rice into the trunk of each tree. Each chip is a laser-etched with information which is stored in a central register held by the police. Paul is quite aware that this kind of data-tagging doesn't (35) ______thieves from stealing the trees in the first place, although it may increase the chances of getting them back. So he's also installing a security alarm system complete with infra-red detectors, in his home.

Question 34

A. look into

B. set about

C. try out

D. go after