Helicobacter

 

 

1. Why did scientists in the past believe that excessive gastric acid secretion was the cause of gastric ulcers?
2. In the 1980s, based on what observations did Barry Marshall consider Helicobacter pylori to be a more plausible cause of gastric ulcers?
3. Among his patients, Helicobacter pylori was detected in the stomachs of all those with gastric ulcers. Can this observation conclusively prove that Helicobacter pylori is definitely the cause of gastric ulcers? Why or why not?
4. If not, suggest other possible sources of error.
5. To prove that Helicobacter pylori causes gastric ulcers, what should the experimental and control groups be?
6. What is the prediction of this experiment?
7. What is the independent variable in this experiment?
8. What is the dependent variable in this experiment?
9. What is the assumption of this experimental design (if any)?
10. What are the control variables in this experimental design?
11. Since mental stress and chronic stress may also cause gastric ulcers, how can the experiment prevent participants from developing ulcers due to stress after knowing they have ingested Helicobacter pylori?
12. In reality, it is difficult to find participants for the experimental group. Suggest possible reasons for this.
13. Some people ingested Helicobacter pylori but did not develop gastric ulcers. Suggest possible reasons for this.
14. Using humans as test subjects can lead to significant errors. Identify possible sources of error and suggest ways to reduce them.
15. In the end, only one person (Barry Marshall) participated in the experimental group. Is this experimental result credible? What methods could be used to address this?
16. Was this scientist risking his life to conduct this experiment? Comment on this approach.
17. What tests should this scientist have conducted beforehand to mitigate health risks?
18. As early as the late 19th and early 20th centuries, Helicobacter pylori had been discovered on the gastric mucosa of ulcer patients, yet scientists did not believe there was a connection between Helicobacter pylori and gastric ulcers. How did they explain these findings?