Maths/skills/stats Flashcards
How do you make a ratio x:1?
Divide first number by second number = x
What is the formula for calculating % change?
(difference/original) x 100
What is the formula for finding the unknown value for glucose concentration?
C1 x V1 (stock) = C2 x V2 (known)
C = concentration
V = volume
What is the formula for calculating Rf value?
distance travelled by solute/distance travelled by solvent
How is ratio converted to a percentage?
e.g. x:1
(x/1) x 100
What is standard deviation?
A measure of the spread of the data around the mean value
What does it mean if there is an overlap in standard deviations?
It is likely there is no significant difference
Why are small samples bad with standard deviation?
Aren’t representative or reliable
How do you calculate rate?
change in y/change in x
When is students T-test used?
When finding the difference between two mean values
When is correlation co-efficient used?
Looking for an association between x and y
When is the Chi squared test used?
When comparing frequencies within categories
What should you include in Evaluate questions?
- No stats test done?
- Small sample size?
- Only focuses on one thing? (e.g. question asks about cancer but data only provides information on LUNG cancer)
- Only starts to be a difference after a certain point? (e.g. drug only starts to have an effect after 5 arbitrary units)
How do you calculate pH when given the concentration of H+ ions?
-log[H+]
How do you calculate concentration of H+ when given the pH value?
10^(-pH)
What does “ln” mean?
Natural log (only used if specified in question)
How do you know whether to draw a tangent or triangle when calculating rate of reaction?
At = tangent
Between = triangle
What is the formula triangle for magnification?
I
A M
I = image size
A = actual size
M = magnification
Definition of resolution
Ability to distinguish between objects close together
Why do light microscopes have poor resolution?
Light has a longer wavelength than electrons
What is the disadvantage to electron microscopes?
Complex specimen preparation - needs to be dead and very thin (involves the use of a vacuum so specimen would burst if alive)
What are the differences between a transmission electron microscope (TEM) and a scanning electron microscope (SEM)?
TEM - highest resolution, electrons pass through specimen, can see detailed internal structure of cells/organelles
SEM - electrons bounce off surface of specimen, 3D image
What are the unit conversions when calculating sizes of cells/organelles?
m x 1000 –> mm
mm x 1000 –> μm
μm x 1000 –> nm
What is the equation for calculating mitotic index?
no. cells with visible chromosomes/total no. cells
