Ch. 1 - A Practical Investigation

AS91601 (B3.1): “Carry out a practical investigation in a biological context with guidance”

$Goal:$

Develop a sound practical investigation
Present a report with a comprehensive discussion of the investigation

The investigation can involve:

The manipulation of variables - isolating a variable to investigate, and controlling the rest

eg. the effect of nutrient levels on plant growth

Investigation of a pattern or relationship
Use of models to predict or explain what might happen in a certain situation, drawing from current knowledge

eg. Predicting the spread of a new strain of COVID-19 based on knowledge on known strains

^^DEVELOPING + CARRYING OUT INVESTIGATION^^

==Select organism==

	Microorganisms*	Plants	Animals
WHAT	Bacteria, fungi, archaea or protistsCANNOT use microorganisms from animal or human sources**	Any plant with photoperiodic needs and life cycle that aligns with investigation period	Small invertebrates - slaters, snails, brine shrimps etc.
}}PROS}}	Allows investigations to carried out easily and quickly in a test tube, petri dish, or under a microscope	Easy to care for and grow	Easy to find and look after & can give very rapid responses; generally available all year round
[[CONS[[	Very strict guidelines for what can be used due to potential pathogenic effectie. CANNOT use microorganisms from animal or human sources**	Can be time consuming

*Strict guidelines for using certain bacteria due to potential pathogenic effect

**Except those found on skin - these can be used but must remain sealed

==Become familiar with the study organism(s)==

You will need to find out the organism(s)’s

Usual habitat/Lifestyle/ecological niche
* This will allow you to look after the organism correctly so the responses/behaviours are a result of investigation and NOT because of physiological stress
How the organism should behave or respond to your investigation and what responses you should keep an eye out for
* Doing pre-reading on typical behaviours of your organism will allow you to identify the causal relationship between the organism response & the factor you are investigating
* If the behaviour is out of the ordinary, you can identify it, and then discuss potential reasons why the organism exhibited such behaviour

Sources of information you can use:

Books or textbooks
Websites
Your experimental observations and/or other students’ experimental observation
Peer-reviewed studies

Aspects to guide your research

Abiotic factors	Biotic factors	Adaptations
Temperature, Light intensity, Humidity, Exposure, Substrate, Nutrients, Water	Distribution of resources, Density, Age structure, Competitors, Predators, Prey	Features that allow the organism to live successfully in its habitat
Gather both qualitative & quantitative data (descriptive & numerical) to:→ Know how to care for it→ Determine the appropriate range for IV*→ Correctly control other variables not under investigation	Important if the investigation involves an interaction or relationship	Important for the discussion of the report to explain your results and referenced results using relevant biological ideas & concepts

*Independent variable

==Formulating a purpose==

Purpose → hypothesis = prediction statement (if xyz happens, then abc will happen)

Checklist for a good hypothesis

[ ] Is the hypothesis easily testable by experimentation?
[ ] Has it specified both the independent and dependent variables (IV & DV)?

Examples

Increasing the intensity of light (independent variable) will increase the intensity of the kinesis response (dependent variable) exhibited by the woodlice

NOTE: When gathering data, you should be gathering data that either supports or rejects the hypothesis, not prove/disprove

It is important to have a precise and well-written hypothesis to develop an experimental plan

==Designing a method==

Rule of thumb - Keep it simple but precise

A good method will:

[ ] Be able to be replicated by someone else

→ This could mean adding diagrams so they know how to use

[ ] Use readily available equipment
[ ] Yield straightforward results to be analysed and interpret
[ ] Be clear about what is being measured - the dependent variable

→ What the DV is

→ How it is going to be measured or sampled

[ ] Be clear about what is being manipulated - the independent variable

→ Must be 1 variable only

→ The IV must have a range of values that are to be investigated

[ ] Indicate variables that need to be controlled to ensure an unbiased and valid experiment

→ How the CV will be controlled

[ ] Outline assumptions that need to be made with this study

→ These are variables outside your control despite your best efforts to control them

[ ] Have precise instructions on collection of data

→ What data will be collected?

→ When will it be measured?

→ What is the unit of measurement?

→ How will it be measured? ie. with what equipment?

→ How the raw data will be processed? ie. will it be averaged?

NOTE: Be prepared to trial and adjust your method. This can ensure that

Sufficient data can be collected from this method
The range for the IV is able to be worked with
Variables that need to be constant are adequately controlled

^^COLLECTING, RECORDING AND PROCESSING DATA^^

==Collecting==

Data should be collected the moment you start studying your organism

→ this could be general observations of its behaviour as well as other factors ie. abiotic or biotic, that are present

==Recording==

Raw data

Unprocessed data
Must still be recorded in a retrievable way
Usually presented in a table/chart format that has

→ A full and informative title

→ Each column or row has a full and informative heading with units where applicable

Process data

To process raw data you either calculate the averages and/or standard deviations
These are recorded and discussed in the results and discussion section of the report
After processing, data is used to draw a graph to identify a relationship between the IV and the DV - or the lack of
Examples: Averages, means, graphs drawn to illustrate patterns or trends, results of any statistical analysis
Two kinds of data

  1. continuous data → measurements where each piece of data can take on any value between the smallest and the largest value in the range
  2. discrete data → counts - ie. no intermediates between adjacent values. “You can’t have 2.5 people!!“

==Formats of data presentation==

[[Line graphs[[	[[Bar charts[[	[[Scattergrams[[
Used for continuous data and show how the IV affects the DV	Used for when there are no intermediates because it cannot be quantified or the data is discrete	Used to show if two variables are correlated. The stronger the correlation, the more the dots = clustered in a line. Randomly scattered if no correlation
[[Histograms[[	[[Kite diagrams[[	[[Pie charts[[
Used to show relative frequency of different measures. Continuous data only	Used to show abundance of organism changes along a chosen transect (line)	Used to indicate % of various constituents of a whole

For every graph make sure

[ ] Title
[ ] Labels
[ ] Units

^^REPORT STRUCTURE^^

Purpose
* Hypothesis linked to a biological concept/idea & meets above requirements
Method
* Final and refined method
* Clearly structured, and as precise & concise as possible without losing essential steps
Results
* Should only contain your processed data - raw data → appendix and logbook
* Should include an interpretation of processed data

→ What does the data presented indicate?

Conclusion: short paragraph
   * State outcome of investigation
   * Identify the relationship between DV and IV
   * Must refer back to hypothesis
   * DO NOT restate/describe results, or discuss the results in terms of the biology of organism
Discussion
   * Explain biological ideas or concepts relevant to investigation
   * Here is where you can synthesise all the information you have learnt together. Including
     * Your findings
     * Other studies and their findings*
     * Key biological concepts relevant to your organism

*try not to spend too much time describing their study, instead, use their studies to support your findings
* Must explain the significance of the results in terms of the biology, not just reiterate/describe

Justification - justify choices you made during the investigation
   * Justify your choice of control variables and how they were maintained
   * Justify your range of values for the independent variable
   * Justify the changes you made to your method
   * A good thing to consider is how all of these affect the validity of your study ie. do these affect the amount of error and bias in your study?
Appendix
* Raw data
* Logbook that was used to record all the observations, changes, and refinement of the investigation process to show the ongoing nature of the investigation
Referencing
   * Correctly use in-text citations or footnotes, and the correct format for the list
   * Reference list = only sources of information actually cited in the report
   * APA 7 is a common style