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Difficulty: EasyTransitions: Chronology and Sequence

The following sentences describe the historical development of penicillin. Arrange them in the correct chronological sequence by ordering the items from first to last.

  1. 1In 1928, Alexander Fleming accidentally discovered penicillin when mold contaminated a petri dish in his laboratory.
  2. 2Afterward, in the late 1930s, Howard Florey and Ernst Chain successfully isolated the active agent.
  3. 3By 1941, the drug was first tested on human patients, showing dramatic curative effects.
  4. 4Shortly thereafter, mass production of penicillin began, saving countless lives during World War II.

Answer

The correct chronological order of the sentences is: first, the initial discovery in 1928; second, the subsequent isolation of the agent in the late 1930s; third, the human testing in 1941; and fourth, the mass production that began shortly thereafter.
The correct sequence begins with the 1928 discovery, followed by the isolation in the late 1930s, continuing to the 1941 trials, and ending with the subsequent mass production.

Step-by-Step Solution

1
Identify the sentence that introduces the starting event or earliest date.
The sentence describing Alexander Fleming's initial discovery in 1928 is identified as the first event in the sequence.
A chronological sequence begins with the earliest dated event that sets the baseline context.
2
Look for transition words or dates indicating the next phase of development.
The sentence starting with 'Afterward, in the late 1930s' is identified as the second event.
The transition 'Afterward' indicates a later step, and the date (late 1930s) directly follows 1928.
3
Identify the next chronological marker following the late 1930s.
The sentence starting with 'By 1941' is identified as the third event.
The year 1941 chronologically follows the late 1930s.
4
Determine the final step using relative sequence transitions.
The sentence beginning with 'Shortly thereafter' describing mass production is identified as the final event.
The phrase 'Shortly thereafter' links the mass production directly to the preceding human trials in 1941.

Key Concept

Identifying chronological markers and sequential transitions to reconstruct a logical timeline.
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Topics

Transitions: Chronology and Sequence

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