Research Methods for the Biosciences: Interactive Exercises

Table of Contents

1. CHAPTER 1: WHERE DO I BEGIN?
2. CHAPTER 2: EXPERIMENTAL DESIGN
3. CHAPTER 3: WHAT TO DO WITH RAW DATA
   1. Exercise 1
   2. Exercise 2
4. CHAPTER 4: AN INTRODUCTION TO HYPOTHESIS TESTING
5. CHAPTER 5: HYPOTHESIS TESTING: DOES MY DATA FIT AN EXPECTED RATIO?
6. CHAPTER 6: HYPOTHESIS TESTING: ASSOCIATIONS AND RELATIONSHIPS
7. CHAPTER 7: HYPOTHESIS TESTING: DO MY SAMPLES COME FROM THE SAME POPULATION? PARAMETRIC DATA
8. CHAPTER 8: HYPOTHESIS TESTING: DO MY SAMPLES COME FROM THE SAME POPULATION? NON-PARAMETRIC DATA
9. CHAPTER 9: RESEARCH, THE LAW AND YOU
10. CHAPTER 10: REPORTING YOUR RESEARCH

Exercise 1

This exercise is based on research carried out by an undergraduate. The topics covered are 3.1, 3.8, and 10.8.1. If you have not read the latter we would still expect you to be able to complete this exercise.

Example W3.1: The production of roots by tobacco explants in response to auxin and kinetin.

An undergraduate investigated the effect of natural and synthetic auxin on the growth of tobacco in tissue culture. There were several different treatments depending on the concentration of auxin (0.00 mg l^-1 to 2.00 mg l^-1) and the concentration of kinetin 0.00 mg l^-1 to 2.00 mg l^-1) in the tissue culture media. These treatments are outlined in Table W3.1. and are numbered 1 - 6. The auxin used in this experiment was either a synthetic auxin (2-4-D) or a natural auxin (IAA).

Table W3.1: The concentrations of an auxin and kinetin in tissue culture media used to examine the growth of tobacco explants.

Media	Auxin (mg l-1)	Kinetin (mg l-1)
1	0.00	0.00
2	0.00	0.20
3	2.00	0.00
4	2.00	0.20
5	2.00	0.02
6	0.02	2.00

After 5 weeks a number of characteristics including the number of roots produced by the leaf explants were recorded by the undergraduate. We reported on some of this data in Example 10.1. The data relating to the number of roots are reproduced here. (The explants on media 5 with the natural or synthetic auxin became contaminated and were excluded from the study).

Explant	No. of roots
IAA 1	10
24D 1	10
1AA 2	0
24D 2	1
IAA 3	27
24D 3	36
IAA 4	0
24D 4	5
IAA 6	3
24D 6	6

1

Q W1.1 What type of data are these? [If you would like to save a record of your answer, please type it into this Word document] a) Discrete b) Continuous c) Qualitative d) Quantitative e) Nominal f) Rankable g) Ordinal scale h) Interval i) Derived variables j) Non-parametric k) Parametric a) Correct. In this investigation you could not expect to get a half a root as a meaningful measure. Therefore this scale of measurement is discrete.a) Incorrect. In this investigation you could not expect to get a half a root as a meaningful measure. Therefore this scale of measurement is discrete.b) You're right - the data are not continuous.b) No - the data are not continuous.c) You're right - the data are not qualitative.c) No - the data are not qualitative.d) Correct. These are numbers and so are quantitative. d) Incorrect. These are numbers and so are quantitative. e) You're right - the data are not nominal.e) No - the data are not nominal.f) Correct. The numbers can be ordered, so are rankable.f) Incorrect. The numbers can be ordered, so are rankable.g) Correct. A discrete but rankable scale is measured as ordinal.g) Incorrect. A discrete but rankable scale is measured as ordinal.h) You're right - the data are not interval.h) No - the data are not interval.i) You're right - the data are not derived variables.i) No - the data are not derived variables.j) Correct. Discrete ordinal data are non-parametric.j) Incorrect. Discrete ordinal data are non-parametric.k) You're right - the data are not parametric.k) No - the data are not parametric.

2

Q W1.2 Organise these data into a suitable table using this Word document to create your table. Have you finished your table? a) Yes b) No Table W3.2: Number of roots produced by tobacco leaf explants in culture on media containing natural or synthetic auxin     Type of media     Type of auxin used in the media 1. 0.00mgl -1 auxin 0.00mgl -1 kinetin 2. 0.00mgl -1 auxin 0.20mgl -1 kinetin 3. 2.00mgl -1 auxin 0.00mgl -1 kinetin 4. 2.00mgl -1 auxin 0.20mgl -1 kinetin 5. 2.00mgl -1 auxin 0.02mgl -1 kinetin 6. 0.02mgl -1 auxin 2.00mgl -1 kinetin Natural auxin (IAA) 10 0 27 0 23 3 Synthetic auxin (2 - 4 D) 10 1 36 5 35 6 Compare your table with ours. One common error would be to label the media types just by the number i.e. 1, 2, 3, 4, 5, 6. If you used such a table in a report/publication there would not be enough information on the table for it to be understood without reference to the text. You need to make sure that your tables can stand alone. Finish your table before proceeding!