问题 单项选择题

下列发生了细胞分化且能体现体细胞全能性的生物学过程是()。

A.玉米种子萌发长成新植株

B.小麦花粉经离体培养发育成单倍体植株

C.胡萝卜根韧皮部细胞经组织培养发育成新植株

D.小鼠骨髓造血干细胞形成各种血细胞

答案

参考答案:C

解析:细胞全能性是指已经分化的细胞仍然具有发育成完整个体的潜能。细胞的全能性以产生个体为标志,若无个体产生,不能体现全能性。细胞分化是指在个体发育中,由一个或一种细胞增殖产生的后代,在形态、结构和生理功能上发生稳定性差异的过程。玉米种子萌发长成新植株过程中发生了细胞分化,是植物体正常的生长发育过程,没有体现细胞的全能性,A错误;小麦花粉是生殖细胞,不是体细胞,B错误:胡萝卜根韧皮部细胞经组织培养发育成新植株过程中发生了细胞分化,该过程也体现了体细胞(胡萝卜根韧皮部细胞)的全能性,C正确;小鼠骨髓造血干细胞形成各种血细胞是细胞分化形成的,该过程没有体现细胞的全能性,D错误。

单项选择题
单项选择题

A variety of illegal acts committed by people in the course of their employment, for their own personal gain, are collectively known as white-collar crime. Embezzlement, theft and trading securities (1) insider information are common forms of white-collar crime. The majority of cases involve low-level employees who steal because they are under (2) financial stress. Many plan to (3) the money back as soon as possible but may never do so. Their crimes are usually never (4) because the amounts of money are small, and no one notices the (5) .

(6) , there are some very large cases of white-collar crime, such as multimillion-dollar stock market or banking seams that take years to discover and are extremely difficult and expensive to (7) .

White-collar crime is not (8) to the business sector. Government employment, especially (9) the city level, also provides opportunities to (10) one’s pockets. (11) , building inspectors accept bribes and full-time employees receive (12) payments.

Although white-collar crime is less (13) than street crime, it involves (14) more money and harm to the public than crimes committed by street criminals. It is (15) that there are more criminals (16) the office suites than in the streets, yet the (17) of white-collar makes it difficult to uncover the offenses and pursue the offenders. As the economy (18) from manufacturing to services and electronic commerce, opportunities for white-collar crime (19) , while the technology needed to stop such crimes will (20) .

13()

A.disastrous

B.hazardous

C.significant

D.violent