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

Question 10: ______ I get your letter, I will reply to you at once.

A. By the time

B. As though

C. As soon as

D. Now that

Ở một loài động vật, nghiên cứu quá trình giảm phân hình thành giao tử của cơ thể có kiểu gen AaBbDdX^MNX^mn người ta nhận thấy có 33,33% số tế bào sinh giao tử có xảy ra hiện tượng tiếp hợp trao đổi chéo gây ra hoán vị gen. Theo lý thuyết, cá thể này cần tối thiểu bao nhiêu tế bào tham gia giảm phân để tạo ra số loại giao tử là tối đa? Biết rằng mọi quá trình sinh học diễn ra bình thường?

A. 8 tế bào hoặc 24 tế bào

B. 18 tế bào hoặc 32 tế bào

C. 24 tế bào hoặc 48 tế bào

D. 12 tế bào hoặc 48 tế bào

Một quần thể có tần số kiểu gen AA là 0,4, tần số kiểu gen aa là 0,3. Hãy tính tần số alen a của quần thể.

A. a=0,3     

B. a=0,35   

C. a=0,6     

D. a=0,45

Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50.

(1) The protozoans, minute, aquatic creatures each of which consists of a single cell of protoplasm, constitute a classification of the most primitive forms of animal life. They are fantastically diverse, but three major groups may be identified on the basis of their motility. The Mastigophora have one or more long tails, which they use to project themselves forward. The Ciliata, which use the same basic means for locomotion as the Mastigophora, have a larger number of short tails. The Sarcodina, which include amoebae, float or row themselves about on their crusted bodies.

(2) In addition to their form of movement, several other features discriminate among the three groups of protozoans. For example, at least two nuclei per cell have been identified in the Ciliata, usually a large nucleus that regulates growth but decomposes during reproduction, and a smaller one that contains the genetic code necessary to generate the large nucleus.

(3) Protozoans are considered animals because, unlike pigmented plants to which some protozoans are otherwise almost identical, they do not live on simple organic compounds. Their cell demonstrates all of the major characteristics of the cells of higher animals.

(4) Many species of protozoans collect into colonies, physically connected to each other and responding uniformly to outside stimulae. Current research into this phenomenon, along with investigations carried out with advanced microscopes may necessitate a redefinition of what constitutes protozoans, even calling into question the basic premise that they have only one cell. Nevertheless, with the current data available, almost 40,000 species of protozoans have been identified. No doubt, as the technology improves our methods of observation, better models of classification will be proposed.

The word “they” in paragraph 3 refers to

A. protozoans      

B. microscopes     

C. investigations   

D. colonies

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

He was a natural singer with a voice that was as clear as _____. 

A. a bell

B. a mirror

C. a waterfall

D. a lake

Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50.

(1) The protozoans, minute, aquatic creatures each of which consists of a single cell of protoplasm, constitute a classification of the most primitive forms of animal life. They are fantastically diverse, but three major groups may be identified on the basis of their motility. The Mastigophora have one or more long tails, which they use to project themselves forward. The Ciliata, which use the same basic means for locomotion as the Mastigophora, have a larger number of short tails. The Sarcodina, which include amoebae, float or row themselves about on their crusted bodies.

(2) In addition to their form of movement, several other features discriminate among the three groups of protozoans. For example, at least two nuclei per cell have been identified in the Ciliata, usually a large nucleus that regulates growth but decomposes during reproduction, and a smaller one that contains the genetic code necessary to generate the large nucleus.

(3) Protozoans are considered animals because, unlike pigmented plants to which some protozoans are otherwise almost identical, they do not live on simple organic compounds. Their cell demonstrates all of the major characteristics of the cells of higher animals.

(4) Many species of protozoans collect into colonies, physically connected to each other and responding uniformly to outside stimulae. Current research into this phenomenon, along with investigations carried out with advanced microscopes may necessitate a redefinition of what constitutes protozoans, even calling into question the basic premise that they have only one cell. Nevertheless, with the current data available, almost 40,000 species of protozoans have been identified. No doubt, as the technology improves our methods of observation, better models of classification will be proposed.

To which class of protozoans do the amoebae belong?

A. Mastigophora  

B. Ciliata     

C. Sarcodina         

D. Motility

Tìm giá trị của số thực m sao cho số phức z = 2 - i 1 + m i  là một số thuần ảo

A. Không tồn tại m.

B. m = - 1 2

C. m = -2

D. m = 2

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42.

The Battle of Gettysburg

One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery.

Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the

battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle.

Question 37: Why does the author mention that "Ewell hesitated to attack"?

A. to explain an important mistake by the Confederates

B. to show that the Confederates were afraid

C. to show that Ewell was against the war

D. none of the answers