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Advanced Higher Biology 🧬🔬 > Experimentation 3.2 > Flashcards

Experimentation 3.2 Flashcards

1
Q

what does validity relate to?

A

variables that are controlled so that any measured effect is likely to be due to the independent variable

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2
Q

what can variables be?

A

continuous os discrete

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3
Q

what does reliability relate to?

A

the confidence in the data and obtaining consistent values in repeats and independent replicates

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4
Q

what does accuracy relate to?

A

how close to the true value data, or means of data sets, are

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5
Q

what does precision relate to?

A

how close measured values are to each other

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6
Q

what is a pilot study used for?

A
  • to help plan procedures
  • assess validity
  • check techniques
  • it is integral to the development of an investigation
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7
Q

what does a pilot study allow?

A

the evaluation and modification of an experimental design

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8
Q

what can the use of a pilot study ensure?

A

-an appropriate range of values for the independent variable
- can help establish the number of repeat measurements required to give a representative value for each independent datum point

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9
Q

what is the independent variable?

A

the variable that is changed in a scientific experiment

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10
Q

what is the dependent variable?

A

the variable that is being measured as the results of a scientific experiment

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11
Q

what do experiments involve?

A

the manipulation of an independent variable by the investigator

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12
Q

what is the experimental group compared to?

A

a control group

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13
Q

what is a simple experimental design?

A

one in which there is one independent variable

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14
Q

what is a multifactorial design?

A

has more than one independent variable or a combination of treatments

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15
Q

what happens if investigators use experimental groups that already exist?

A

there will be no truly independent variable

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16
Q

what does the control of laboratory conditions allow?

A

simple experiments to be conducted more easily than n the field

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17
Q

what are drawbacks?

A

findings that ay not be applicable to a wider setting

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18
Q

what are observational studies good at detecting?

A

correlation

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19
Q

what are observational studies not good at determining and why?

A

causation as they do not directly test a hypothesis

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20
Q

what is not being directly controlled by the investigator for ethical or logistical reasons in observational studies?

A

the independent variable

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21
Q

what may affect the dependent variable due to the complexities of biological systems?

A

confounding variables

22
Q

why must confounding variables be held constant if possible or at least monitored?

A

so that their effect on the result can be accounted for in the analysis

23
Q

what could be used where confounding variables cannot be controlled easily?

A

a randomised block design

24
Q

how can randomised blocks of treatments and control groups be distributed?

A

in such a way that the influence of any confounding variable is likely to be the same across treatment and control groups

25
Q

what are control results used for and what types of controls may be used?

A

the comparison with the results of treatment groups
- negative and positive controls may be used

26
Q

what does a negative control provide?

A

results in the absence of a treatment

27
Q

what is a positive control?

A

a treatment that is included to check that the system can detect a positive result when it occurs

28
Q

placebos lacking the independent variable being investigated can be included as a treatment in what?

A

human trials

29
Q

what is the placebo effect?

A

a measurable change in the dependent variable as a result of a human patient’s expectations, rather than changes in the independent variable

30
Q

what does in vitro refer to?

A

the technique of performing a given procedure in a controlled environment outside of a living organism

31
Q

what are examples of in vitro experiments?

A
  • cells growing in a culture medium
  • proteins in solution
  • purified organelles
32
Q

what are the advantages of in vitro studies?

A
  • controllable
  • repeatable
  • rapid
  • cheap
  • may avoid ethical and regulatory issues
33
Q

what are the disadvantages of in vitro studies

A
  • extrapolation is difficult
  • chronic effects are not tested
34
Q

what does in vivo refer to?

A

experimentation using a whole living organism

35
Q

what are the advantages of in vivo studies?

A
  • simulate real life
  • chronic effects can be tested
36
Q

what are the disadvantages of in vivo studies?

A
  • difficult to control
  • slow
  • expensive
  • may have ethical and regulatory issues
37
Q

when may a representative sample of a population be selected?

A

where it is impractical to measure every individual in a population

38
Q

what determines the appropriate sample size?

A

he extent of the natural variation within a population

39
Q

more variable populations require what?

A

larger sample sizes

40
Q

what should a representative sample share with the population as a whole?

A

the same mean and the same degree of variation about the mean

41
Q

what happens in random sampling?

A

members of the population have an equal chance of being selected

42
Q

what happens in systematic sampling?

A

members of a population are selected at regular intervals because of an environmental gradient

43
Q

what happens in stratified sampling?

A

a non-homogenous population is divided into categories called strata that are then sampled proportionally

44
Q

what may variation in experimental results be due to?

A

the reliability of measurement methods and/or inherent variation in the specimens

45
Q

how can the reliability of measuring instruments or procedures be determined?

A
  • by repeated measurements or readings of an individual datum point
  • the variation observed indicates the precision of the measurement instrument or procedure, but not necessarily its accuracy
46
Q

how can the natural variation in the biological material being used be determined?

A

by measuring a sample of individuals from the population

47
Q

what does the mean of repeated measurements indicate?

A

the true value being measured

48
Q

what us the rage if values measure of?

A

the extent of variation in the results

49
Q

what does it mean for the variation if there is a narrow range?

A

the variation is low

50
Q

what does the independent replication involve and why is it carried out?

A
  • repeating experimental procedures with a different investigator, or in a different laboratory, or at a different time
  • it is carried out to produce independent data sets
51
Q

how can overall results be considered reliable?

A

only if they can be achieved consistently

52
Q

why should independent data sets be compared?

A

to determine the reliability of the results

Advanced Higher Biology 🧬🔬 (19 decks)

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