Homework #2 Read the research article by Xie et al. (2013) The ISME Journal 7: 1
ID: 206578 • Letter: H
Question
Homework #2 Read the research article by Xie et al. (2013) The ISME Journal 7: 1544-1555, and answer the following questions using 1 to 3 complete and concise sentences.
1. Does this research article describe discovery- or hypothesis- based science?
2. What is the hypothesis of this research article?
3. In what two sections of this research article did you find the hypothesis stated?
4. What were the three independent variables described in the “Thermal tolerance assay” subsection of the Materials and methods?
5. What were the three dependent variables described in the “Thermal tolerance assay” subsection of the Materials and methods?
6. What were three of the many control variables described in the “Thermal tolerance assay” subsection of the Materials and methods?
7. Which bacterial strain was optimal for thermal tolerance?
8. How does Figure 1 support the researcher’s hypothesis? Please provide specific details.
9. What are the independent variables shown in Figure 5, and what is the dependent variable in all 4 graphs?
10. Give one example from the Discussion section of how the authors supported their hypothesis?
Explanation / Answer
1. The first part of the study is discovery based science. They had cultures of algae that got contaminated by bacteria and then they realized that the algae in those cultures were resistant to heat. Then they went to propose the hypothesis by looking into the background of already existing studies.
2.The hypothesis is that the interaction between cobalamin producing bacteria and C. reinhardtii would result in the heat tolerance of the latter thanks to the biosynthesis of cobalamin dependent methionin synthase (METH) by the algae.
3. In the abstract and at the end of the first paragraph of the introduction.
4. The independent variables are those that are cotrolled by the experiment, the conditions in which the experiment is done. In this case the three variables are: The temperature, the presence or absence of bacteria and the presence or absence of cobalamin or methionine amendments.
5. The dependent variables on the other hand are those that change thanks to the independent variables. In this case, viability, cobalamin production and morphology by epifluorescence imaging.
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