Maths/skills/stats

Question 1

How do you make a ratio x:1?

Answer 1

Divide first number by second number = x

Question 2

What is the formula for calculating % change?

Answer 2

(difference/original) x 100

Question 3

What is the formula for finding the unknown value for glucose concentration?

Answer 3

C1 x V1 (stock) = C2 x V2 (known)

C = concentration
V = volume

Question 4

What is the formula for calculating Rf value?

Answer 4

distance travelled by solute/distance travelled by solvent

Question 5

How is ratio converted to a percentage?

Answer 5

e.g. x:1

    (x/1) x 100

Question 6

What is standard deviation?

Answer 6

A measure of the spread of the data around the mean value

Question 7

What does it mean if there is an overlap in standard deviations?

Answer 7

It is likely there is no significant difference

Question 8

Why are small samples bad with standard deviation?

Answer 8

Aren’t representative or reliable

Question 9

How do you calculate rate?

Answer 9

change in y/change in x

Question 10

When is students T-test used?

Answer 10

When finding the difference between two mean values

Question 11

When is correlation co-efficient used?

Answer 11

Looking for an association between x and y

Question 12

When is the Chi squared test used?

Answer 12

When comparing frequencies within categories

Question 13

What should you include in Evaluate questions?

Answer 13

1. No stats test done?
2. Small sample size?
3. Only focuses on one thing? (e.g. question asks about cancer but data only provides information on LUNG cancer)
4. Only starts to be a difference after a certain point? (e.g. drug only starts to have an effect after 5 arbitrary units)

Question 14

How do you calculate pH when given the concentration of H+ ions?

Answer 14

-log[H+]

Question 15

How do you calculate concentration of H+ when given the pH value?

Answer 15

10^(-pH)

Question 16

What does “ln” mean?

Answer 16

Natural log (only used if specified in question)

Question 17

How do you know whether to draw a tangent or triangle when calculating rate of reaction?

Answer 17

At = tangent
Between = triangle

Question 18

What is the formula triangle for magnification?

Answer 18

I
A M

I = image size
A = actual size
M = magnification

Question 19

Definition of resolution

Answer 19

Ability to distinguish between objects close together

Question 20

Why do light microscopes have poor resolution?

Answer 20

Light has a longer wavelength than electrons

Question 21

What is the disadvantage to electron microscopes?

Answer 21

Complex specimen preparation - needs to be dead and very thin (involves the use of a vacuum so specimen would burst if alive)

Question 22

What are the differences between a transmission electron microscope (TEM) and a scanning electron microscope (SEM)?

Answer 22

TEM - highest resolution, electrons pass through specimen, can see detailed internal structure of cells/organelles

SEM - electrons bounce off surface of specimen, 3D image

Question 23

What are the unit conversions when calculating sizes of cells/organelles?

Answer 23

m x 1000 –> mm
mm x 1000 –> μm
μm x 1000 –> nm

Question 24

What is the equation for calculating mitotic index?

Answer 24

no. cells with visible chromosomes/total no. cells

Question 25

What is the equation for calculating how long cells spent in one stage of mitosis?

Answer 25

(number of cells in that stage/total number of cells) x time taken for 1 cell cycle

Question 26

How do you calculate the no. of chromosome combinations from meiosis?

Answer 26

2^n

Question 27

How do you calculate the no. of chromosome combinations from meiosis AND random fertilisation?

Answer 27

(2^n)^2

Question 28

What is the equation which links rate of diffusion, SA, conc. gradient and diffusion distance?

Answer 28

Rate of diffusion = (surface area x concentration gradient) / diffusion distance

Question 29

What is the cardiac output equation?

Answer 29

cardiac output = heart rate x stroke volume

Question 30

What is the pulmonary ventilation equation?

Answer 30

pulmonary ventilation = tidal volume x ventilation rate