Practicals

Question 1

What is the null hypothesis

Answer 1

There is no significant difference between two variables

Question 2

T test

Answer 2

Comparing two means

Significant difference between two means

Question 3

Chi squared

Answer 3

Looks at difference between observed and expected
Compare to critical value
N-1 (N=number of data you are looking at)
>=significant

Question 4

Explain why rate of bubbling can measure photosynthesis

Answer 4

More o2 oxygen bubbles released per second

Higher rate of photosynthesis and greater rate of photolysis

Question 5

Paper chromatography

Answer 5

Pen ink would run with solvent

Question 6

What is the syringe used for
Why is it more accurate than measuring bubbles of gas
Don’t put leaf in blender

Answer 6

To fill with gas to measure air given off and measure phs
There is a scale and quantity of gas can be seen/quantitative

There are hardly any chloroplasts

Question 7

Control experiment

Answer 7

If there was a colour change without solution then colour change was not because of phs

Question 8

Why not shake the tubes

Answer 8

Oxygen gets in
Acts as a terminal electron acceptor
Turns blue
Methyl blue gains electrons from etc from aerobic respiration from glucose and yeast from produced reduced bad and fad from kerbs cycle

Question 9

Reason for selecting specific data

Answer 9

Remove selective bias
Random sample
Remove bias

Question 10

Transects

Answer 10

Measure with quadrat at intervals

Question 11

Told to wipe inside of maze between experiments. Explain why?

Answer 11

Maggots follow each other
Maggot particles for heat
Chemotaxis

Equal light at each turn
Low light because heat might be a factor
Dim and evenly distributed

Question 12

Keep temperature constant

Answer 12

Put temperaturethermometer in
Add hot/cold water

Use water bath
Air temperature fluctuates more than liquid temperature

Question 13

Why use a big sample

Answer 13

Large sample size to identify anomalies
Time constraints
Calculate a reliable mean

Question 14

Use maggots more than once

Answer 14

No, may have gone a different way . Show turn alternation

Question 15

Control

Answer 15

Set a base to get expected values

To allow comparison

Question 16

Reversing maggots direction affects movement of animal

Answer 16

Could artificially increase results
Not reliable
Can
Go over same part

Question 17

Observations

Answer 17

Dry and smooth/not spherical

Question 18

Why repeat

Answer 18

To standardise results
Can compare
Get standard deviation/means

Question 19

Variables for temperature

Answer 19

Time
Which hand used
Position of arm on surface

Question 20

Why people matched for factor

Answer 20

Older people have eye sight differences/stimuli so longer reaction times as muscles are weaker

Some races have different alleles so different reaction times

Body size the length of neurones are longer

More caffeine- quicker at synapses- drugs- sympathetic neurone

Humans have taxis? Taxis to music/warm environment- kinesis/ where they live

Brain involved so not protective mechanism

Question 21

Hydrogen carbon lit indicator

Answer 21

Colour change has no scale
Not impirical
No numerical value
Binary

Use colorimeter
Check light intensity

Question 22

Can you get an average from two values

Answer 22

No, some people hold for longer

Yes,can get concordant results

Question 23

Properties of co2

Answer 23

Forms carbonic acid with water (blow into limewater experiment)

Question 24

Hand variation can you roll your tongue

Answer 24

D

Question 25

Phenotype

Answer 25

Is the physical phenotype applied to organisms

Question 26

Why hardy Weinberg is not applied to human populations

Answer 26

There is migration Different alleles Higher mutation rate than animals

Question 27

Continuous and discrete data

Answer 27

Continuous-controlled by multiple alleles and environmental factors e.g.

Question 28

Why plot as scatter diagram

Answer 28

Easier to see correlation | One variable against another

Question 29

Things you | Compare

Answer 29

If means overlap in sd Size of sd If they do, no significant difference

Question 30

Why do you use leaves of same plant species

Answer 30

Different plants have different size and length and width | Less genetic variation

Question 31

Why don’t you cut the leaves

Answer 31

May damage shape/environment Ethics/damages habitat May shrivel up

Question 32

True length v measured length

Answer 32

Harder to measure true value | Standardise to compare

Question 33

Differences in standard error interpreted

Answer 33

When hw does not work

Question 34

Why not use mark release recapture on humans

Answer 34

Unethical to mark humans People don’t want to Hard to recapture

Question 35

Gel electrophoresis | Pcr

Answer 35

``` Make a gene machine/ select gene Heat to 95 so hydrogen bonds break Bases join complementary By DNA polymerase Annealed One strand can get other strand Is a chain reaction Cooked to 72 Cooled to 55 All split act as templates Exponential increase ```

Question 36

Spearmans rank

Answer 36

Association between two variables

Question 37

Not necessary to get pigments out

Answer 37

Crushing can get pigments out

Question 38

Aseptic techniques when transfers broth culture to agar plate

Answer 38

``` Keep lid on Petri dish -Open lid as little as possible -prevent unwanted bacteria contaminating the dish Wear gloves Prevent contamination from bacteria on hands/mouth Wash hands/wear mask Use sterile pipette by flaming the loop - to maintain a pure culture of bacteria ```