1.
Lazzaro Spallanzani and Louis Pasteur both performed experiments hoping to disprove spontaneous generation. What conditions existed in Pasteur’s experiment that did not exist in Spallanzani’s?
Correct Answer
A. Air could enter the flasks, but no microorganisms could enter.
Explanation
In Pasteur's experiment, air could enter the flasks but no microorganisms could enter. This was achieved by using curved neck flasks that allowed air to enter but prevented microorganisms from entering. This was a key difference from Spallanzani's experiment, where he sealed the flasks completely to prevent both air and microorganisms from entering. By allowing air to enter, Pasteur was able to show that the presence of microorganisms in the flasks was due to contamination from the air, rather than spontaneous generation.
2.
John Needham performed an experiment testing spontaneous generation. He boiled chicken broth, placed it in a sterile flask, and then sealed the flask. After a few days, Needham observed microorganisms in the flask. Based on current understanding, how was his experiment flawed?
Correct Answer
B. Boiling the broth did not kill all microorganisms present.
Explanation
John Needham's experiment was flawed because boiling the broth did not kill all microorganisms present. This allowed the remaining microorganisms to continue growing and multiplying, leading to the observation of microorganisms in the flask after a few days.
3.
Who helped disprove the idea of spontaneous generation by demonstrating that maggots come from fly eggs and NOT from meat?
Correct Answer
A. Francesco Redi
Explanation
Francesco Redi helped disprove the idea of spontaneous generation by demonstrating that maggots come from fly eggs and not from meat. He conducted an experiment where he placed meat in two different jars - one covered and one uncovered. The meat in the uncovered jar attracted flies, which laid eggs on it, resulting in the development of maggots. However, the covered jar, which prevented flies from accessing the meat, did not produce any maggots. This experiment provided evidence that living organisms do not spontaneously generate but rather come from pre-existing living organisms.
4.
Spontaneous generation was offered as an explanation for
Correct Answer
C. The appearance of maggots on rotting meat.
Explanation
Spontaneous generation was a theory that suggested living organisms could arise from non-living matter. It was commonly believed that maggots spontaneously generated from rotting meat. This theory was later disproven by experiments conducted by Francesco Redi and Louis Pasteur, who showed that maggots only appeared on meat when flies laid their eggs on it. Therefore, the correct answer is the appearance of maggots on rotting meat.
5.
How did Redi test the hypothesis of spontaneous generation?
Correct Answer
B. He placed meat in two containers and covered one of them. He then observed the containers for the appearance of maggots.
Explanation
Redi tested the hypothesis of spontaneous generation by placing meat in two containers and covering one of them. By observing the containers for the appearance of maggots, Redi was able to determine whether maggots spontaneously generated from the meat or if they were the result of flies laying eggs on the meat. If maggots appeared only in the uncovered container, it would suggest that flies were responsible for the generation of maggots, supporting the idea of biogenesis rather than spontaneous generation.
6.
What did Pasteur do in his experiments on spontaneous generation that other scientists before him had not done?
Correct Answer
C. He used curve-necked flasks and left them open.
Explanation
Pasteur's experiments on spontaneous generation were different from those of other scientists before him because he used curve-necked flasks and left them open. This design allowed air to enter the flask but prevented dust and microorganisms from contaminating the broth. By doing so, Pasteur was able to demonstrate that the growth of microorganisms in the broth was due to the introduction of airborne microorganisms, rather than the spontaneous generation of life.
7.
In an experiment, a scientist filled 2 open flasks, as shown in the figures, with broth and boiled the broth until it became clear. He then left the flasks open for several days.
Which results would show that spontaneous generation did not occur?
Correct Answer
D. The broth in Flask A became cloudy, and the broth in Flask B remained clear.
Explanation
If the broth in Flask A became cloudy and the broth in Flask B remained clear, it suggests that spontaneous generation did not occur. Spontaneous generation refers to the theory that living organisms can arise from non-living matter. In this experiment, if both flasks remained clear, it could indicate that the broth was contaminated with microorganisms that caused cloudiness. However, if only Flask A became cloudy, it suggests that the contamination occurred in that specific flask, while Flask B remained clear, indicating that the microorganisms did not spontaneously generate in the broth.