authentication task Flashcards
accuracy
refers to how close the results are to the truth.
precision
refers to how similar the results are to each other.
repeatability
Repeatability refers to the closeness of agreement between the results of successive measurements of the same quantity being measured, carried out under the same conditions of measurement. eg same method, observer, loaction, measuring instrument
reproducibility
Reproducibility refers to the closeness of agreement between the results of the measurements of the same quantity being measured, carried out under changed conditions of measurement. eg different observers, time, laboatories. methods of measurements
validity
A measurement is ‘valid’ if it measures what it claims to be measuring. Both experimental design and the implementation should be considered when evaluating validity.
What are errors and the 2 types
Errors are caused by uncontrolled extraneous variables. The two types of experimental errors are systematic errors and random errors.
What are systematic errors?
Systematic errors occur consistently and affect the accuracy of the data. The data is affected in the same way.
What are random errors?
Random errors affect the precision of a measurement and are always present in measurements.
Know examples of systematic errors and how we can reduce them in an experiment. How do systematic errors affect the results?
They are caused by faulty equipment eg scale always reading 2g higher than true value
Systematic errors cause instrumental readings to differ from the true value by a consistent amount each time a measurement is made, so that all the readings are shifted in one direction from the true value.
Can be reduced by calibrating equipment
Example: A scale always reading 2g higher than the true value.
Know examples of random errors and how we can reduce them in an experiment. How do random errors affect the results?
These types of errors are unpredictable variations in the measurement process and result in a spread of readings or data points.
Examples- unpredictable changes eg in temp, inability to read an instrument,
The effect of random errors can be reduced by making more or repeated measurements and calculating a new mean and/or by refining the measurement method or technique..
What is a controlled experiment?
A controlled experiment is one where all variables are kept constant except for the independent variable.
what is a hypothesis?
A hypothesis is your prediction for the outcome of the experiment , based on your observations and should be testable.
If the beetroot cells are placed in a high concentration of ethanol, then they will be highly permeable seen by a higher reading on the colorimeter.
What are the main steps in the scientific method?
A series of steps employed by scientists to investigate a problem or research question
Formulate a question
Research the question
Form a hypothesis
Design controlled experiment which identifies sources of experimental errors
Analyse data
Draw conclusuins
Communicate results
What are qualitative and quantitative results?
Quantitative results are data represented by numbers, while qualitative results are data that cannot be represented by numbers.
What is an independent variable?
An independent variable is what we are changing in our experimental setup, represented on the x-axis.
What is a dependent variable?
A dependent variable is what we are measuring as being affected by the independent variable, represented on the y-axis.
What are controlled variables?
Controlled variables are factors we are keeping the same in our experiment to test the relationship between the independent and dependent variables.
Why must a control be included in an experiment?
A control is used as a comparison to see how the dependent variable is affected when there is no independent variable.
structure of plasma membrane
The plasma membrane consists of a phospholipid bilayer with proteins embedded in it. The phospholipid molecules have hydrophilic heads (which face outward toward the aqueous environment) and hydrophobic tails (which face inward, away from water). This arrangement helps create a semi-permeable barrier. Embedded proteins serve various functions like transport, signaling, and cell recognition. The membrane also contains cholesterol, which maintains fluidity, and carbohydrate chains attached to proteins and lipids, contributing to cell recognition.
function of plasma membrane
The plasma membrane is selectively permeable, meaning it regulates the movement of substances into and out of the cell. It allows essential molecules like oxygen and nutrients to enter and waste products to exit, while preventing the passage of harmful substances. This selective permeability is achieved through various mechanisms, such as passive transport (diffusion, osmosis) and active transport (requiring energy).
How was absorbance used in our investigation to determine membrane permeability?
In your investigation, absorbance was used to measure the amount of pigment (betacyanin) released from beetroot cells when the plasma membrane became more permeable. The greater the disruption to the membrane (e.g., from ethanol), the more pigment was released into the surrounding solution. Absorbance readings, taken using a colorimeter, were used to quantify the amount of pigment in the solution, which serves as an indicator of membrane permeability.
How does a colorimeter work?
A colorimeter measures the absorbance of light by a sample. It works by passing light of a specific wavelength through the sample and measuring the amount of light that is absorbed. The absorbance is proportional to the concentration of a substance, in this case, the pigment released from the beetroot cells. A higher absorbance indicates a higher concentration of pigment, suggesting greater membrane permeability.
Be able to summarise your findings about how your independent
variable affected membrane permeability.
As ethanol concentration increased, the permeability of the plasma membrane in beetroot cells also increased. This was indicated by higher absorbance values, meaning more pigment was released from the cells. Ethanol disrupts the lipid bilayer, making it more permeable to molecules like betacyanin.
What errors did you encounter in your investigation?
Random errors: Temperature fluctuations in the room and sunlight through the window could cause variations in the results due to their effects on membrane permeability. Inconsistent beetroot size
Systematic errors: The curvettes not being cleaned properly may have caused contamination or inaccuracies in absorbance readings. Additionally, parallax errors when reading measurements on test tubes could have resulted in incorrect volumes of ethanol being used.
