Cho một số phát biểu sau về các gen thuộc ôperon Lac ở E.coli

(1) Mỗi gen mã hóa cho 1 chuỗi pôlipeptit khác nhau.

(2) Mỗi gen đều có vùng điều hòa riêng nằm ở đầu 3^’ của mạch mã gốc.

(3) Các gen có số lần nhân đôi và phiên mã bằng nhau.

(4) Sự nhân đôi, phiên mã và dịch mã của các gen đều diễn ra ở tế bào chất.

(5) Khi phiên mã, mỗi gen đều tạo 1 phân tử mARN riêng biệt.

Số phát biểu đúng là:

A. 4.

B. 3.

C. 2.

D. 1.

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 difference between the nuclear family and the extended family is that a nuclear family refers to a single basic family unit of parents and their children, whereas the extended family refers to their relatives such as grandparents, in-laws, aunts and uncles, etc. In many cultures, and particularly indigenous societies, the latter is the most common basic form of social organization.

A nuclear family is limited, according to Kristy Jackson of Colorado State University, to one or two parents (e.g. a father and mother) and their own child, or children, living together in a single house or other dwellings. In anthropology, they only must be related in this fashion; there is no upper or lower limit on the number of children in a nuclear family.

The extended family is a much more nebulous term, but in essence refers to kin or relations not covered by the above definition. In historical Europe and Asia as well as in Middle Eastern, African, and South American Aboriginal cultures, extended family groups were typically the most basic unit of social organization. The term can differ in specific cultural settings, but generally includes people related in age or by lineage. Anthropologically, the term “extended family” refers to such a group living together in a household, often with three generations living together (grandparents, parents, and children) and headed in patriarchal societies by the eldest man or by some other chosen leadership figure. However, in common parlance, the term “extended family” is often used by people simply to refer to their cousins, aunts, uncles, and so on, even though they are not living together in a single group.

Historically, most people in the world have lived in extended family groupings rather than in nuclear families. This was even true in Europe and in the early United States, where multiple generations often lived together for economic reasons. During the 20th century, average income rose high enough that living apart as nuclear families became a viable option for the vast majority of the American population. In contrast, many indigenous societies and residents of developing countries continue to have multiple generations living in the same household. The rise of the nuclear family in the modern West does not necessarily mean that family arrangements have stabilized, either. The rapid growth in single-parent households, for instance, also represents a substantial change in the traditional nuclear family. More couples are also choosing not to have children at all.

Which of the following is TRUE according to the passage?

A. Since the 20th century, more and more American couples have lived in extended families because of the financial burdens

B. Nuclear families are the most basic form of social organization all over the world

C. The popularity of nuclear families in western countries helps to stabilize family arrangement

D. Traditional nuclear families have changed a lot over times

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 days of the camera-toting tourist may be numbered. Insensitive travelers are being ordered to stop pointing their cameras and camcorders at reluctant local residents. Tour companies selling expensive trips to remote corners of the world, off the well-trodden path of the average tourist, have become increasingly irritated at the sight of the visitors upsetting locals. Now one such operator plans to ban clients from taking any photographic equipment on holidays. Julian Mathews is the director of Discovery Initiatives, a company that is working hand-in-hand with other organizations to offer holidays combining high adventure with working on environmental projects. His trips are not cheap; two weeks of white-water rafting and monitoring wildlife in Canada cost several thousand pounds.

 Matthews says he is providing 'holidays without guilt', insisting that Discovery Initiatives is not a tour operator but an environmental support company. Clients are referred to as 'participants' or 'ambassadors'. 'We see ourselves as the next step on from eco-tourism, which is merely a passive form. of sensitive travel - our approach is more proactive.'

 However, says Matthews, there is a price to pay. 'I am planning to introduce tours with a total ban on cameras and camcorders because of the damage they do to our relationships with local people. I have seen some horrendous things, such as a group of six tourists arriving at a remote village in the South American jungle, each with a video camera attached to their face. That sort of thing tears me up inside. Would you like somebody to come into your home and take a photo of you cooking? A camera is like a weapon; it puts up a barrier and you lose all the communication that comes through body language, which effectively means that the host communities are denied access to the so-called cultural exchange.'

 Matthews started organizing environmental holidays after a scientific expedition for young people. He subsequently founded Discovery Expeditions, which has helped support 13 projects worldwide. With the launch of Discovery Initiatives, he is placing a greater emphasis on adventure and fun, omitting in the brochure all references to scientific research. But his rules of conduct are strict. 'In some parts of the world, for instance, I tell people they should wear long trousers, not shorts, and wear a tie, when eating out. It may sound dictatorial, but I find one has a better experience if one is well dressed. I don't understand why people dress down when they go to other countries.'

 Matthews' views reflect a growing unease among some tour companies at the increasingly cavalier behaviour of well-heeled tourists. Chris Parrott, of Journey Latin America, says: 'We tell our clients that indigenous people are often shy about being photographed, but we certainly don't tell them not to take a camera. If they take pictures without asking, they may have tomatoes thrown at them.' He also reports that increasing numbers of clients are taking camcorders and pointing them indiscriminately at locals. He says: 'People with camcorders tend to be more intrusive than those with cameras, but there is a payoff - the people they are filming get a tremendous thrill from seeing themselves played back on the viewfinder.'

 Crispin Jones, of Exodus, the overland truck specialist, says: 'We don't have a policy but, should cameras cause offence, our tour leaders will make it quite clear that they cannot be used. Clients tend to do what they are told.

 Earthwatch, which pioneered the concept of proactive eco-tourism by sending paying volunteers to work on scientific projects around the world, does not ban cameras, but operates strict rules on their use. Ed Wilson, the marketing director of the company, says: 'We try to impress on people the common courtesy of getting permission before using their cameras, and one would hope that every tour operator would do the same. People have to be not only environmentally aware but also culturally aware. Some people use the camera as a barrier; it allows them to distance themselves from the reality of what they see. I would like to see tourists putting their cameras away for once, rather than trying to record everything they see.'
Question:The word ‘courtesy’ in the last paragraph is closest in meaning to

A. dignity

B. politeness

C. nobility

D. elite