equations 😟

Question 1

ADD ALL EQUATIONS HERE 😘

Answer 1

Yass

Question 2

(Add more) 🟡🟡
What is m1 x v1 = m2 x v2
(Finding v1 usually)

Answer 2

Concentration of orig sol. x vol of orig sol.
=
Conc by end (TOTAL) x vol by end (TOTAL)

10 represents m1 (unless otherwise)
The (eg. 5ml) solution is v2
Final conc is on table

Question 3

How do we use a calibration curve

Answer 3

1. Make different known sugar concentrations
2. Use colorimeter to measure absorbance/transmission
   Of each conc and plot cal curve on graph
3. Find conc of sample from calibration curve

Question 4

How to find uncertainties

Answer 4

Amount of uncertainty is
+/- half the smallest division on the scale measuring with

Eg. Smallest division is 5ml
+/- 2.5 ml
80ml +/- 2.5

…

With 2 or more uncertainties
1. Find all uncertainties
2. Add measured volumes
3. Add to get combined uncertainty
4. Combine answers from last 2 steps to get the total volume and uncertainty
NEEDED SAME UNITS

Question 5

How to work out percentage error

Answer 5

(Uncertainty/ measured value) x100

Question 6

How to describe using a calibration curve to find unknowns

Answer 6

• make different known sugar concentrations
• use colorimeter to measure absorbance of each conc
• plot calibration curve on graph
• find conc of sample from using curve

Question 7

Mitotic index

Answer 7

( Cells in mitosis / total cell no. ) x 100
= percentage of cells undergoing mitosis

Question 8

Why do we use percentages

Answer 8

Allows comparisons between different starting values

Question 9

What to put for evaluating questions (studies)

Answer 9

+ tends to be data fitting pattern (quote)

• no control
• untruthful/subjective response
• some data not fitting pattern(quote)
• done in animals not humans
• small sample is unrepresentative
• one group (eg. Male)
• correlation not causation

Question 10

What are statistical tests for and what are null hypotheses

Answer 10

Tell us whether patterns in data are due to chance or real differences
No statistical difference = due to chance (accept)

Eg. Will be no statistically significant difference/correlation
Between both variables

Question 11

Critical value and P value - what is it

Answer 11

It’s an estimate of probability that result occurred
By statistical accident

If p value is large, unlikely statistical significance (by chance)
If p value is small, likely statistical significance (not chance)
p value = 0.05 (means less than 5% chance that it’s due to chance)

,.

To work out if less than 5% chance it’s due to chance
The CRITICAL VALUE has to be greater/equal to TEST STATISTIC (given)
To be a statistically significant difference/correlation (reject)

The CRITICAL VALUE has to be lower that TEST STATISTIC
to be by chance (accept)

Question 12

What’s the degrees of freedom

Answer 12

Along y axis of table.
It’s the number in sample (in chi square, category number) MINUS 1

The x axis is the p value (0.05)

Find what they make when they meet = critical value

Question 13

Different types of stats tests

Answer 13

• T test
Finding if there’s a difference between means of two data sets
Two sets of data measure same thing (DV)
But are two conditions
—> distribution graph

• chi squared
Finding if there’s a difference between expected and observed data
Measure same things (DV) . Data’s from different conditions
—> bar chart

•spearman’s rank
Finding if correlationbetween two variables
Which are completely different (diff units)
Two sets of data measuring different things (see if correlation)
—> scatter graph

Question 14

What are logarithmic scales

Answer 14

Hard to plot large values on a graph, where data is so spread out
—> log scales go up in order of magnitude, so each mark on scale 10x bigger than last
- eg pH
- bacteria growth
- richter scale

How to do..
Using log then typing in value
Tells you how many times 10 has been multiplied by itself to get the value

Shift then log and then typing value
Tells the opposite (the original value from log)

Question 15

What are uncertainties

Answer 15

Uncertainty is +/- half the smallest division on a scale
You’re measuring with

Balance eg goes up in 10g so uncertainty is +/-5g
—> ie margin of error is 5g each side (10g)

Question 16

What are the key points in sampling

Answer 16

Always use random sampling, smallest as possible sample and analyse data appropriately

Question 17

What are key points in standard deviation

Answer 17

> is the spread of data around mean
If it overlaps has no significant difference
Always mention!