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Advanced Higher Biology: Unit 3 - Investigative Biology > Experimentation > Flashcards

Experimentation Flashcards

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1
Q

What is the independent variable ?

A

The factor we seek to change or control in a scientific experiment to test the effects on the dependent variable

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2
Q

What is the dependent variable?

A

The variable being tested and measured in a scientific experiment that will be affected by changing the independent variable

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3
Q

How can you determine that validity of any change in the dependent variable?

A

By using a control

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4
Q

What is a confounding variable?

A

Any factor which affects the dependent variable that is not the independent variable

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5
Q

What is important to consider with confounding variables?

A

The confounding variables must be held constant if possible or at least monitored so that their effect on the results can be accounted for in analysis

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6
Q

Give the 7 advantages of pilot studies

A

Allows a new protocol to be developed
Ensures an appropriate range of values for the independent variable
Allows practice of an established protocol
Avoids results for the dependent variable going ‘‘off the scale’’
Checks whether results can be produced in a suitable time frame
Allows the number of repeat measurements required to be estimated
Allows identification of confounding variables which can then be controlled

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7
Q

What are variables?

A

factors which can be changed, controlled or measured within an experiment.

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8
Q

What is a pilot study?

A

A pilot study is a small-scale investigation of a planned research project.

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9
Q

Why are pilot studies integral to the development of any research project?

A

due to their ability to flag up potential issues with a main study and therefore prevent costly mistakes, time wasting or even failure of the project as a whole.

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10
Q

What are discrete variables? Give example.

A

Discrete variables are distinct and unrelated to each other.
e.g. an experiment investigating the effect of different chemicals on Daphnia heart rate, the independent variable (the different chemicals) is discrete.

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11
Q

How are discrete variables are graphed?

A

Experiments where the independent variable is discrete display results using bar graphs.

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12
Q

What are continuous variables? Give example.

A

Continuous variables have a range of values.

e.g. an experiment investigating the effect of temperature on Daphnia heart rate, the independent variable (temperature) is continuous.

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13
Q

How are continuous variables graphed?

A

Experiments with a continuous independent variable display results using line graphs.

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14
Q

What are the 3 types of data?

A

Qualitative
Quantitative
Ranked

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15
Q

Explain qualitative data.

A

Descriptive and difficult to measure directly.
Recorded using direct counts or by observation. Difficult to analyse.
Presented using bar graph or pie chart.

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16
Q

Explain quantitative data.

A

Measured directly.
Recorded as numbers.
Easier to analyse.
Presented using a line or scatter graph, or a histogram.

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17
Q

Explain ranked data.

A

Data is put into order of magnitude (from smallest to largest or least common to most common).
Presented using a bar graph.

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18
Q

Give examples of qualitative data.

A

Colour of leaf, softness of fur, emotions

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19
Q

Give examples of quantitative data.

A

Concentration of solution, time and height.

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20
Q

Give examples of ranked data.

A

Abundance of plant, dominance hierarchies in animals.

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21
Q

What do observational studies use to carry out an investigation?

A

groups that already exist.

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22
Q

Describe the issue with observational studies.

A

Because observational studies use groups that already exist, the researcher is not able to tightly control the composition of the experimental groups.
This means there is the potential for bias in the groups to affect the results of the study and there is no truly independent variable.
As a result, these ‘observational’ studies are good at detecting correlation but, as they do not directly test the model, they are less useful for determining causation.

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23
Q

What is blocking?

A

Blocking is a practice whereby if confounding variables cannot be controlled their effects are minimised by selecting control and experimental groups in which the effects of confounding variables are equal.

24
Q

If it is not practical to test the control and experimental group at the same time of day and day of week, what should be kept the same in both the control and experimental groups?

A

the variance of testing times and number of participants

25
Q

What do simple experiments involve?

A

Simple experiments involve a single independent variable.

26
Q

What does a multifactorial experiment involve?

A

A multifactorial experiment involves a combination of more than one independent variable or combination of treatments.

27
Q

What does an in vitro experiment describe? Give example.

A

An in vitro experiment describes an investigation which is carried out using biological molecules or cells out with their normal biological system, e.g. cell culture.

28
Q

Give a negative of using in vitro experiments.

A

An in vitro experiment may be easily controlled but its relevance may be limited in vivo.

29
Q

What does an in vivo experiment describe? Give example.

A

An in vivo experiment describes an investigation which is carried out using a living organism, e.g. mouse model organism.

30
Q

What do In vivo experiments allow researchers to do?

A

researchers to investigate the overall effect of an agent on a living organism.

31
Q

Why must In vivo testing using an animal model be performed before advancing to human clinical trials?

A

as this will allow the investigators to assess the performance of the drug within a biological system.

32
Q

What are the 2 types of controls?

A

positive

negative

33
Q

What is a positive control?

A

A positive control is a treatment that is included to check that the system can detect a positive result when it occurs. This group is expected to have a positive result and proves to the researcher that the experimental design being used is capable of producing results.

34
Q

What is a negative control?

A

A negative control group provides results in the absence of a treatment. If a negative control yields an unexpected result this could suggest that there is an unknown confounding variable affecting the experiment and therefore the results would be considered invalid.

35
Q

What should a representative sample share?

A

the same mean and the same degree of variation about the mean as the population as a whole.

36
Q

How is the degree of variation within a population is often determined?

A

by calculating standard deviation (SD).

37
Q

What is standard deviation?

A

a measure which allows the amount of variation in a set of data to be quantified.

38
Q

What are the 3 types of sampling?

A

random sampling
systematic sampling
stratified sampling

39
Q

Describe random sampling.

A

Members of the population have an equal chance of being selected.
This reduces the possibility of bias in the sampling group. The individuals are numbered and selected at random to form the sample group.

40
Q

What are the advantages of random sampling?

A

It is a straightforward process and avoids bias in the sample group.

41
Q

What are the disadvantages of random sampling?

A

It can result in poor representation of the main population/area if certain things are not selected by the random numbers generated.
There may also be issues with accessing all the selected members of the population or sites from an area of study

42
Q

Describe systematic sampling.

A

Members of a population are selected at regular intervals.

In an environmental study, systematic sampling may involve samples being taken in a regular pattern.

43
Q

What are the advantages of systematic sampling?

A

It should provide a more representative sample of the population as a whole (compared to random sampling).

44
Q

What are the disadvantages of systematic sampling?

A

May be biased because all members (or areas) do not have an equal chance of being selected.

45
Q

Describe stratified sampling.

A

The population is divided into categories that are then sampled proportionally. This means the population is organised into groups according to some characteristic and the number of individuals sampled from each group is in proportion to the group’s size in the main population.

46
Q

What are the advantages of systematic sampling?

A

It should give a sample which is highly representative of the population as a whole.

47
Q

What are the disadvantages of systematic sampling?

A

The proportions of each group within the main population must be known.
In order to identify the relative proportion of each group, the researcher must have access to accurate, up-to-date population data and this is not always available.

48
Q

What does the term precision mean?

A

The closeness of repeated measurements to one another

49
Q

What does the term accuracy mean?

A

A measure of how close the data is to the actual true value

50
Q

What does the term validity mean?

A

Refers to whether conclusions drawn from a set of results are credible. Valid results rely on sound experimental design and execution

51
Q

What does the term reliability mean?

A

Refers to whether a procedure yields consistent results each time it is repeated

52
Q

Explain precision within an experiment

A

Precise results are obtained when the data has very little spread about the mean value.

53
Q

Explain accuracy within an experiment

A

Accuracy of measuring equipment can be improved by performing a calibration with a known standard. This can improve the accuracy of the data which is collected

54
Q

Explain validity within an experiment

A

Results are considered valid if all confounding variables have been controlled; therefore, only the independent variable affected the dependent variable.

55
Q

Explain reliability within an experiment

A

Carrying out repeat measurements within an investigation can improve the reliability of the results. A result is considered reliable if it can be re-produced both by the initial researcher and other scientists.

Advanced Higher Biology: Unit 3 - Investigative Biology (3 decks)

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