Critical Evaluation of Biological Research

Question 1

What standard format should scientific reports follow? (6)

Answer 1

1. Title - this should be descriptive and helpful.
2. Summary or abstract - short paragraph outlining the aims and findings.
3. Introduction - a concise account providing clear, relevant and unambiguous background information of a suitable depth and detail, whilst justifying the purpose of the study.
4. Methods - clear and detailed to allow easy repetition by a peer.
5. Results - these should be laid out in an appropriate format, e.g. tables with graphs.
6. Discussion - both procedures and results should be evaluated here, allowing valid conclusions to be formed.

Question 2

What should the introduction do? (7)

Answer 2

1. provide the reader with sufficient information to understand specific aspects of the methods, results and ultimately the discussion;
2. provide convincing justification for the study;
3. place the study in the context of what is already known and understood about the topic;
4. review any key points which both support and contradict the information provided;
5. contain several sources to support statements, and citations and references should be in a standard form;
6. give details about the ethical considerations behind the decisions made when selecting the particular study methods and organisms;
7. contain clear aims and hypotheses.

Question 3

In order to make a conclusion, the experiment procedure must be evaluated and deemed to be valid and reliable. What things should be considered? (5)

Answer 3

• procedures - these should test the aim or hypothesis;
• controls - should be present where appropriate to determine that any effects are the result of the treatment or show the effect in the absence of a treatment;
• controlled variables - the validity of an experiment may be compromised where factors other than the independent variable may have influenced the dependent variable. A good example of this is ensuring pH remains constant using buffers and temperature remains constant using a water bath;
• sample size - must be large enough to state without bias that any effect on the dependent variable was due to changing the independent variable. Of course we know from earlier in this unit that in some experiments there may be no effect, and that a negative result can be just as valid. When taking a sample this must be done randomly to ensure that the sample is representative of the entire population, thus preventing selection bias;
• repetition - experiments must then be repeated in full at a different time using new ingredients to determine reliability.

Question 4

Data can be further analysed through the appropriate use of simple statistical procedures. Give 7 examples of these procedures.

Answer 4

• Graphs
• Error Bars
• Mean
• Median
• Mode
• Range
• Standard Deviation

Question 5

What are statistical tests used to determine?

Answer 5

whether the results are likely or unlikely to have occurred by chance.

Question 6

In evaluating conclusions, what must be considered? (3)

Answer 6

• The aim of the study
• The results obtained
• The validity and reliability of the experimental design

Question 7

Describe positive correlation.

Answer 7

increase in the independent variable seems connected to the increase in the dependent variable.

Question 8

Describe negative correlation.

Answer 8

dependent variable decreases as the independent variable is increased.