Trong các phát biểu sau đây có bao nhiêu phát biểu đúng về ưu thế lai

Cho các phát biểu sau đây, có bao nhiêu phát biểu nói đúng về ưu thế lai?1. Trong việc tạo ưu thế lai người ta không sử ?

Cho các phát biểu sau đây, có bao nhiêu phát biểu nói đúng về ưu thế lai?
1. Trong việc tạo ưu thế lai người ta không sử dụng phương pháp lai thuận nghịch vì để tiến hành lai thuận nghịch cần rất nhiều thời gian và trang thiết bị hiện đại.
2. Ưu thế lai biểu hiện con lai có năng suất cao, phẩm chất tốt.
3. Con lai có ưu thế lai cao được sử dụng làm giống.
4. Sinh trưởng nhanh, phát triển tốt, sức sống cao.
5. Để tạo ra ưu thế lai, người ta thường sử dụng phép lai khác dòng.

A. 2.

B. 1.

C. 3.

D. 5.

Cho các phát biểu sau đây về ưu thế lai:

[1] Ưu thế lai biểu hiện cao nhất ở cơ thể mang nhiều cặp gen đồng hợp trội nhất.

[2] Lai thuận nghịch có thể làm thay đổi ưu thế lai ở đời con.

[3] Chỉ có một số tổ hợp lai giữa các cặp bố mẹ nhất định mới có ưu thế lai cao.

[4] Người ta không sử dụng con lai có ưu thế cao làm giống vì chúng không đồng nhất về kiểu hình.

[5] Phương pháp sinh sản sinh dưỡng là phương pháp phổ biến nhất để duy trì ưu thế lai ở thực vật.

[6] Phương pháp sử dụng hai dòng thuần chủng mang các cặp gen tương phản để tạo con lai có ưu thế lai được gọi là lai khác dòng kép.

Số phát biểu không đúng

A. 1

B. 2

C. 3

Đáp án chính xác

D. 4

Xem lời giải

Cho các phát biểu sau đây, có bao nhiêu phát biểu nói đúng về ưu thế lai? 1. Trong ưu thế lai người ta không sử dụng phương pháp lai thuận nghịch vì để tiến hành lai thuận nghịch cần rất nhiều thời gian và trang thiết bị hiện đại.

Khi nói về ưu thế lai, có bao nhiêu phát biểu sau đây không đúng?

[1] Ưu thế lai biểu hiện cao nhất ở đời F1, sau đó giảm dần qua các thế hệ.

[2] Ở con lai, ưu thế lai cao hay thấp không phụ thuộc vào trạng thái dị hợp tử về nhiều cặp gen khác nhau.

[3] Khi lai giữa 2 cá thể thuộc cùng 1 dòng thuần chủng luôn cho con lai có ưu thế lai.

[4] Khi lai giữa 2 dòng thuần chủng có kiểu gen khác nhau, phép lai thuận có thể không có ưu thế lai nhưng phép lai nghịch lại có thể cho ưu thế lai và ngược lại.

[5] Các con lai F1 có ưu thế lai luôn được giữ lại làm giống.

Khi nói về ưu thế lai, có bao nhiêu phát biểu sau đâyđúng? [1]. Các cá thể con có ưu thế lai cao sẽ được sử dụng làm giống. [2]. Cá thể con có ưu thế lai thường mang kiểu gen dị hợp về các cặp gen. [3]. Để tạo ưu thế lai người ta cho lai các dòng bố mẹ thuần chủng khác nhau. [4]. Các cá thể con có ưu thế lai có kiểu hình vượt trội so với bố mẹ.

A.

1

B.

2

C.

3

D.

4

Đáp án và lời giải
Đáp án:C
Lời giải:

Ưu thế lai: hiện tượng cơ thể lai [F1] xuất hiện những phẩm chất ưu tú, vượt trội so với bố mẹ chẳng hạn như có sức sống cao hơn, sinh trưởng nhanh, phát triển mạnh, chống chịu bệnh tật tốt, năng suất cao, thích nghi tốt. [1] sai, các cá thể có ưu thế lai thường được sử dụng vào mục đích kinh tế vì ưu thế lai giảm dần qua các thế hệ [2] đúng, [theo giả thuyết siêu trội] [3] đúng [4] đúng

Vậy đáp án là C

Bạn có muốn?

Xem thêm các đề thi trắc nghiệm khác

Xem thêm

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

  • Số hạng không chứa

    trong khai triển
    là:

  • 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 41 to 50:

    Until recently, most American entrepreneurs were men. Discrimination against women in business, the demands of caring for families, and lack of business training had kept the number of women entrepreneurs small. Now, however, businesses owned by women account for more than $40 billion in annual revenues, and this figure is likely to continue rising throughout the 1990s. As Carolyn Doppelt Gray, an official of the Small Business Administration, has noted, "The 1970s was the decade of women entering management, and the 1980s turned out to be the decade of the woman entrepreneur". What are some of the factors behind this trend? For one thing, as more women earn advanced degrees in business and enter the corporateworld, they are finding obstacles. Women are still excludedfrom most executive suites. Charlotte Taylor, a management consultant, had noted, "In the 1970s women believed if they got an MBA and worked hard they could become chairman of the board. Now they've found out that isn't going to happen, so they go out on their own". In the past, most women entrepreneurs worked in "women's" fields: cosmetics and clothing, for example. But this is changing. Consider ASK Computer Systems, a $22-million-a-year computer software business. It was founded in 1973 by Sandra Kurtzig, who was then a housewife with degrees in math and engineering. When Kurtzig founded the business, her first product was software that let weekly newspapers keep tabs on their newspaper carriers and her office was a bedroom at home, with a shoebox under the bed to hold the company's cash. After she succeeded with the newspaper software system, she hired several bright computer-science graduates to develop additional programs. When these were marketed and sold, ASK began to grow. It now has 200 employees, and Sandra Kurtzig owns $66.9 million of stock. Of course, many women who start their own businesses fail, just as men often do. They still face hurdlesin the business world, especially problems in raising money; the banking and finance world is still dominated by men, and old attitudes die hard. Most businesses owned by women are still quite small. But the situation is changing; there are likely to be many more Sandra Kurtzigs in the years ahead.

    Question41:What is the main idea of this passage?

  • Tìm số hạng không chứa

    trong khai triển
    biết

  • 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 41 to 50:

    Until recently, most American entrepreneurs were men. Discrimination against women in business, the demands of caring for families, and lack of business training had kept the number of women entrepreneurs small. Now, however, businesses owned by women account for more than $40 billion in annual revenues, and this figure is likely to continue rising throughout the 1990s. As Carolyn Doppelt Gray, an official of the Small Business Administration, has noted, "The 1970s was the decade of women entering management, and the 1980s turned out to be the decade of the woman entrepreneur". What are some of the factors behind this trend? For one thing, as more women earn advanced degrees in business and enter the corporateworld, they are finding obstacles. Women are still excludedfrom most executive suites. Charlotte Taylor, a management consultant, had noted, "In the 1970s women believed if they got an MBA and worked hard they could become chairman of the board. Now they've found out that isn't going to happen, so they go out on their own". In the past, most women entrepreneurs worked in "women's" fields: cosmetics and clothing, for example. But this is changing. Consider ASK Computer Systems, a $22-million-a-year computer software business. It was founded in 1973 by Sandra Kurtzig, who was then a housewife with degrees in math and engineering. When Kurtzig founded the business, her first product was software that let weekly newspapers keep tabs on their newspaper carriers and her office was a bedroom at home, with a shoebox under the bed to hold the company's cash. After she succeeded with the newspaper software system, she hired several bright computer-science graduates to develop additional programs. When these were marketed and sold, ASK began to grow. It now has 200 employees, and Sandra Kurtzig owns $66.9 million of stock. Of course, many women who start their own businesses fail, just as men often do. They still face hurdlesin the business world, especially problems in raising money; the banking and finance world is still dominated by men, and old attitudes die hard. Most businesses owned by women are still quite small. But the situation is changing; there are likely to be many more Sandra Kurtzigs in the years ahead.

    Question 44: In the passage, “that” refers to_________.

  • Sau khi khai triển và rút gọn biểu thức

    thì
    có bao nhiêu số hạng?

  • Trong khai triển nhịthức
    .Cótất cả
    sốhạng.Vậy
    bằng:
  • 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 41 to 50:

    Until recently, most American entrepreneurs were men. Discrimination against women in business, the demands of caring for families, and lack of business training had kept the number of women entrepreneurs small. Now, however, businesses owned by women account for more than $40 billion in annual revenues, and this figure is likely to continue rising throughout the 1990s. As Carolyn Doppelt Gray, an official of the Small Business Administration, has noted, "The 1970s was the decade of women entering management, and the 1980s turned out to be the decade of the woman entrepreneur". What are some of the factors behind this trend? For one thing, as more women earn advanced degrees in business and enter the corporateworld, they are finding obstacles. Women are still excludedfrom most executive suites. Charlotte Taylor, a management consultant, had noted, "In the 1970s women believed if they got an MBA and worked hard they could become chairman of the board. Now they've found out that isn't going to happen, so they go out on their own". In the past, most women entrepreneurs worked in "women's" fields: cosmetics and clothing, for example. But this is changing. Consider ASK Computer Systems, a $22-million-a-year computer software business. It was founded in 1973 by Sandra Kurtzig, who was then a housewife with degrees in math and engineering. When Kurtzig founded the business, her first product was software that let weekly newspapers keep tabs on their newspaper carriers and her office was a bedroom at home, with a shoebox under the bed to hold the company's cash. After she succeeded with the newspaper software system, she hired several bright computer-science graduates to develop additional programs. When these were marketed and sold, ASK began to grow. It now has 200 employees, and Sandra Kurtzig owns $66.9 million of stock. Of course, many women who start their own businesses fail, just as men often do. They still face hurdlesin the business world, especially problems in raising money; the banking and finance world is still dominated by men, and old attitudes die hard. Most businesses owned by women are still quite small. But the situation is changing; there are likely to be many more Sandra Kurtzigs in the years ahead.

    Question 43:All of the following were mentioned in the passage as detriments to women in the business world EXCEPT__________.

  • Cho đa giác đều

    đỉnh nội tiếp một đường tròn. Số tam giác tù được tạo thành từ
    trong
    đỉnh của đa giác là

  • 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 36 to 40:

    Since water is the basis of life, composing the greater part of thetissuesof all living things, the crucial problem ofdesert animals is to survive in a world where sources of flowing water are rare. And since man’s inexorable necessity is to absorb large quantities of water at frequent intervals, he can scarcely comprehend that many creatures of the desert pass their entire lives without a single drop.

    Uncompromising as it is, the desert has not eliminated life but onlythose formsunable to withstand its desiccating effects. No moist-skinned, water-loving animals can exist there. Few large animals are found. The giants of the North American desert are the deer, the coyote, and the bobcat. Since desert country is open, it holds more swift-footed running and leaping creatures than the tangled forest. Its population is largely nocturnal, silent, filled with reticence, and ruled by stealth. Yet they are notemaciated.

    Having adapted to their austere environment, they are as healthy as animals anywhere else in the word. The secret of their adjustment lies in the combination of behavior and physiology. None could survive if, like mad dogs and Englishmen, they went out in the midday sun; many would die in a matter of minutes. So most of them pass the burning hours asleep in cool, humid burrows underneath the ground,emerging to hunt only by night. The surface of the sun-baked desert averages around 150 degrees, but 18 inches down the temperature is only 60 degrees.

    Question 38:The phrase “those forms” in the passage refers to all of the following EXCEPT

  • 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 36 to 40:

    Since water is the basis of life, composing the greater part of thetissuesof all living things, the crucial problem ofdesert animals is to survive in a world where sources of flowing water are rare. And since man’s inexorable necessity is to absorb large quantities of water at frequent intervals, he can scarcely comprehend that many creatures of the desert pass their entire lives without a single drop.

    Uncompromising as it is, the desert has not eliminated life but onlythose formsunable to withstand its desiccating effects. No moist-skinned, water-loving animals can exist there. Few large animals are found. The giants of the North American desert are the deer, the coyote, and the bobcat. Since desert country is open, it holds more swift-footed running and leaping creatures than the tangled forest. Its population is largely nocturnal, silent, filled with reticence, and ruled by stealth. Yet they are notemaciated.

    Having adapted to their austere environment, they are as healthy as animals anywhere else in the word. The secret of their adjustment lies in the combination of behavior and physiology. None could survive if, like mad dogs and Englishmen, they went out in the midday sun; many would die in a matter of minutes. So most of them pass the burning hours asleep in cool, humid burrows underneath the ground,emerging to hunt only by night. The surface of the sun-baked desert averages around 150 degrees, but 18 inches down the temperature is only 60 degrees.

    Question 37:Man can hardly understand why many animals live their whole life in the desert, as________.

Phát biểu nào sau đây là đúng về ưu thế lai?


Câu 50703 Thông hiểu

Phát biểu nào sau đây là đúng về ưu thế lai?


Đáp án đúng: d

Phương pháp giải

Chọn tạo giống dựa trên nguồn biến dị tổ hợp --- Xem chi tiết
...

Video liên quan

Chủ Đề