unit 3: investigative biology KA 1-3: Scientific principles and process, Experimentation, and Reporting and critical evaluation of biological research Flashcards
scientific cycle definition
observation; connstruction of a testable hypothesis; experimental design; gathering, recording and analysis of data; evaluation of reults and conclusion; the formation of a revised hypothesis where necessary
what is a null hypothesis
the null hypothesis proposed that there will be no statistically significant effect as a result of the experiment treatment
what is peer review
specialists with expertise in the relevant field assess the scientific quality of a submitted manuscript and make recommendations regarding its suitability for publication
what are review articles
summarises current knowledge and recent findings in a particular field
what is a primary paper
a report on the results of an experiment by the person or group who performed it
describe the process of peer reveiw
other scientists, who are specialists with expertice in the relavent feild asess the scientific quality of a submitted manuscript & make recomendations regarding its sutability for publication
name the 3 R’s that must be considered when conducting animal studies
-reduction
-replacement
-refinement
what does reduction mean when conducting animal studies
reduce the number of animals in a study (without compromising the alidity or reliability)
what does replacement mean when conducting animal studies
avoid using animals when an alternitive cellular module system exists
what does refinement mean when conducting animal studies
techniques should be adjusted to minimise harm to animals
name the key points that must be followed when conducting human studies
-confidentiality
-the right to withdraw data
-informed consent (do they agree to take part and do they know what possible consequences could be)
what does the term valididty mean
variables controlled so that any measured effect is likely to be due to the independant variable
what does the term reliability mean
consistent values in repeats and independant replicates
what does the term accuracy mean
data, or means of data sets, are close to true value
what does the term precision mean
measured values are close to each other
what is a pilot study
a small scale study conducted to refine values for independent and controlled variables prior to conducting an experiment
what is an independent variable
an independent variable is the variable that is changed in a scientific experiment
what is a dependant variable
a dependant variable is the variable that is being measured in a scientific experiment
what is a discrete variable
the measurements fall into distinct groups/dont have a unit- ie blood type, yes/no, left/right, eye colour, hair colour
what is a continuous variable
measurements have a range of values between a minimum and maximum/have a unit- ie height, temperature, time
name the two types of studies
experimental and observational
what is an experimental study
an experiment that involves the manipulation of the independent variable by the investigator
what is a randomised block design
an experiment in which treatment and control groups can be distributed in such a way that the influence of any confounding variables are likely to be the same across the treatment control groups
(example- splitting up the groups into males and females before splitting again into the treatment and control groups)
what is a negative control
provides results in the absence if treatment
what is a positive control
a treatment that us included to check that the system or equipment can detect when positive results occur
define the placebo effect
a measurable change in the independent variable as a result of a patient’s expectations, rather than changes in the independent variable
definition of an in vitro study
preforming a given procedure in a controlled environment outside if a living organism (cells growing in culture or proteins in solution)
definition of an in vivo study
experimentation using a whole, living organism (a drug trial or environmental sampling)
advantages of an in vitro study
-can be tightly controlled
-this permits the use of simple experiments with clear & accurate findings
disadvantages of an in vitro study
the findings may not be applicable in a wider setting
advantages of an in vivo study
more true to life than studies done in a lab
disadvantages of an in vivo study
-more complex to account for the wider range of confounding variables
-the independent variable is often not under direct control & there is almost always something that cannot be controlled
describe the random sampling method
members of the population have an equal chance of being selected
describe the systematic sampling method
members of the same population are selected at regular intervals
describe the stratified sampling method
the population is divided into categories that are then sampled proportionately
what is selection bias
the selection of a sample in a non-random way, so that the sample is not representative of the whole population
describe how selection bias can be avoided when sampling
By sampling populations randomly
what do box plots not have
error bars and the mean
what is a positive corelation
where an increase in one variable is accompanied by an increase in another variable
what is a negative corelation
where an increase in one variable is accompanied by an decrease in another variable
describe a strong and weak correlation
strength of correlation is proportional to the spread of values from the line of best fit
define a statistically significant result
a result that is unlikely to be due to chance alone
how could you tell if a result was statistically significant from the error bars alone
if the error bars do not overlap, then the results are significantly different. if the error bars do overlap, then the results are not statistically significant
