Vật liệu di truyền là DNA được truyền lại cho đời sau thông qua cơ chế di truyền nào sau đây?

Ý nào đúng: Nguyên tắc tối ưu của thiết kế kĩ thuật là gì?

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 28 to 34.

Foot-racing is a popular activity in the United States. It is seen not only as a competitive sport but also  as  a  way  to  exercise,  to  enjoy  the camaraderie  of  like-minded  people,  and  to  donate  money  to  a good  cause.  Though  serious  runners  may  spend  months  training  to  compete,  other  runners  and  walkers might not train at all. Those not competing to win might run in an effort to beat their own time or simply to enjoy the fun and exercise. People of all ages, from those of less than one year (who may be pushed in strollers)  to  those  in  their  eighties,  enter  into  this  sport.  The  races  are  held  on  city  streets,  on  college campuses, through parks, and in suburban areas, and they are commonly 5 to 10 kilometers in length.
The  largest  footrace  in  the  world  is  the  12-kilometer  Bay  to  Breakers  race  that  is  held  in  San Francisco every spring. This race begins on the east side of the city near San Francisco Bay and ends on the west side at the Pacific Ocean. There may be 80,000 or more people running in this race through the streets and hills of San Francisco. In the front are the serious runners who compete to win and who might finish  in  as  little  as  34  minutes.  Behind  them  are  the  thousands  who  take  several  hours  to  finish.  In  the back of the race are those who dress in costumes and come just for fun. One year there was a group of men who dressed like Elvis Presley, and another group consisted of firefighters who were tied together in a  long  line  and  who  were  carrying  a  fire-hose.  There  was  even  a  bridal  party,  in  which  the  bride  was dressed  in  a  long  white  gown  and  the  groom  wore  a  tuxedo.  The  bride  and  groom  threw  flowers  to bystanders, and they were actually married at some point along the route.

The main purpose of this passage is to _________.

Tốc độ sóng là

Công dân có các nghĩa vụ gì khi tham gia bầu cử, ứng cử?

Chọn câu đúng trong các câu sau?

Choose the word pronounced differently from the rest: famous, another, about, appear

Bộ phận nào sau đây của vùng biển Việt Nam được coi như lãnh thổ trên đất liền?

Nguyên tử nguyên tố X (Z = 12) có cấu hình electron là

Trong bối cảnh toàn cầu hóa, các nước ta đã nhanh chóng nắm bắt được cơ hội nào nhằm thúc đẩy sự phát triển kinh tế - xã hội?

Trong thiên nhiên cây tre có thể sinh sản bằng cơ quan nào?

Đọc đoạn trích dưới đây và trả lời các câu hỏi:

Sáng nay mùa thu sang

Cha đưa con đi học

Sương đọng cỏ bên đường

Nắng lên ngời hạt ngọc

Lúa đang thì ngậm sữa

Xanh mướt cao ngập đầu

Con nhìn quanh bỡ ngỡ

Sao chẳng thấy trường đâu?

Hương lúa tỏa bao la

Như hương thơm đất nước

Con ơi đi với cha

Trường của con phía trước

Thu 1964

(Tế Hanh, Đưa con đi học, In trong Khúc ca mới, NXB Văn học, HN, 1966)

Hiện tượng từ ngữ nào sau đây nêu đúng mối quan hệ về nghĩa của từ “đường” trong bài thơ trên và từ “đường” trong cụm từ “Ngọt như đường”?

Đầu ra của bàn là là gì?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

Biting into a ripe, juicy fruit brings a smile to many people’s faces. But eating that same fruit a week before it is ripe probably wouldn’t be as enjoyable! Unripe fruits are often hard and bitter, but that serves a purpose. The hard exterior of an unripe fruit protects the developing seed inside. After a seed fully develops inside the fruit, the fruit changes color, softens, and gets sweeter to become more attractive to animals and humans. These organisms eat the fruit and spread its seeds, ensuring the plant’s survival and regrowth.

But how does a fruit ripen? The ripening process involves many complex chemical reactions. When a fruit ripens, it goes through a chemical change. A chemical change happens when bonds within molecules break, and the atoms that once formed them regroup into new molecules. Chemical changes are irreversible. Once a fruit ripens, it cannot become unripe again.

One molecule responsible for this chemical change is ethylene. Ethylene (C2H4) is a colorless gas made up of carbon and hydrogen atoms. (I). It is a naturally occurring molecule in the atmosphere. (II). It is also an important plant hormone. (III). Plants release ethylene through the growing tips of roots, flowers, and ripening fruit. (IV). Although ethylene serves other purposes in plants, one of its main purposes is to trigger the chemical reactions that cause fruits to ripen. As the fruit matures, oxygen in the air helps stimulate the production of ethylene. This ethylene production is a signal that begins fruit ripening. For that reason, unripe fruits have low levels of ethylene, while ripe fruits have higher levels of ethylene. Most fruits produce ethylene and respond to ethylene in the atmosphere.

Although fruits require ethylene to ripen, different types of fruits respond to this molecule in two distinct ways: non-climacteric fruits and climacteric fruits. Non-climacteric fruits do not ripen after harvesting. They produce very little ethylene of their own. Climacteric fruits, on the other hand, continue to ripen after they are picked. These fruits produce a large amount of ethylene. Climacteric fruits can also speed up the ripening process of other fruits nearby since they release high levels of ethylene into the air.  

Where in the passage does the following sentence best fit in paragraph 3?

“Plant hormones are chemicals produced by plants that control their growth, reproduction, maturation, and decay.”