Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. The re
searchers grew one type of bacteria in twenty-four identical covered petri dishes. Then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. They left the remaining six petri dishes closed as a control group. When the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. The researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. Which statement best explains why the researchers’ conclusion was not justified?
The experiment tested too many variables.
The control group was not treated the same as the experimental group.
The sample size of twenty-four petri dishes is not large enough.
The single type of bacteria is not adequate to make any conclusions.
The correct answer will be option-The control group was not treated the same as the experimental group.
Explanation:
A scientific experiment is performed to test the predicted hypothesis which in the given case is that "different hand sanitizes have a different effect on the growth of the bacteria".
The researcher divides 24 samples into two groups- 18 Petri-dishes divided into 3 groups with 6 Petri dish receiving different sanitizers each and rest 6 as control samples without treatment of the hand sanitizers.
The researcher performed the mistake while doing the experiment as he opened the experimental Petri dishes and kept them open whereas in the control group he kept the Petri dish closed which lead to the error in the results as the control showed least growth of the bacteria which should be high.
This happened because the control and the experimental samples were not provided with the same question and thus is the correct answer.
In 2011 NASA researchers identified features on Mars known as Recuring Slope Lineae ( or RSL ). RSL are relatively dark and narrow features.They are thought to be a signs of salty liquid water on Mars. One hypothesis for RSL formation is that they form when underground bodies of salty water leak into the surface. Answer: Recuring Slope Lineae.
The dual nature of light means that light behaves as a wave. If the light consisted of small particles, the alternating light and dark bands would not have occurred.
Sometimes it behaves like a particle (called a photon), which explains how light travels in straight lines.
