问题 单项选择题

如果用3H、15N、32P、35S标记噬菌体后,让其侵染细菌,在产生的子代噬菌体的组成结构成分中,能够找到的放射性元素()

A.外壳中可找到15N和35S、3H

B.DNA中可找到3H、15N、32P

C.外壳中可找到15N和35S

D.DNA中可找到15N、32P、35S

答案

参考答案:B

解析:子代噬菌体中DNA组成元素由亲代噬菌体DNA和细菌的脱氧核苷酸决定,子代噬菌体的蛋白质组成元素由细菌的氨基酸决定,所以在子代噬菌体的DNA中找到3H、15N和32P

单项选择题
单项选择题

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.

While most people agree that the Golden Age of comic books began with the introduction of Superman in 1938 in Action Comics #1, there is less agreement about when exactly the Golden Age ended. There is a general consensus, however, about the factors that brought the Golden Age to a close: the rise of the horror comic book in the late 1940s, and the resulting backlash against comic books in the early 1950s.

Superhero comic books reached their peak of popularity in the early 1940s because of all the GIs in Europe and Japan who eagerly read about Superman, Batman, and The Spirit. When these soldiers came home, they still wanted to read comic books, but they sought out more adult content. William Gaines of EC Comics was happy to meet the market demand with such grim and gritty titles as Weird Fantasy and The Crypt of Terror. The creators of superhero comic books, not wanting to be left behind, responded by matching their protagonists against darker criminals in more violent encounters.

These darker comic books aroused the anger of child psychologist Fredric Wertham, who believed that comic books were leading the nation’s youth into crime, violence, and drug abuse. Wertham’s book, The Seduction of the Innocent, was a national best-seller that helped bring about congressional investigations into the corrupting influence of comic books. The Senate committee that reviewed Wertham’s charges decided to create the Comics Code Authority, a regulatory body that prohibited comic books from mentioning sexuality, alcohol, drugs, criminal behavior, or any themes related to the horror genre.

These regulations had a numbing effect on the industry. EC Comics was nearly driven out of the comics business, and the other major players canceled many of their most prominent titles. The comics business did not recover until the Marvel revolution of the early 1960s ushered in the Silver Age.

According to the passage, which of the following was true of the creators of superhero comic books in the postwar years ?()

A. They sought to head off the censorship of the Comics Code Authority by voluntarily prohibiting stories dealing with sexuality, drugs, or criminal behavior.

B. They introduced characters such as Superman and The Spirit.

C. They unintentionally laid the groundwork for the transition from the Golden Age of comic books to the Silver Age.

D. They focused increasingly on flashy artwork and less on well-developed stories.

E. They responded to the competitive pressure from horror comic books by increasing the amount of violence in their stories.