Practicals Flashcards
What is the null hypothesis
There is no significant difference between two variables
T test
Comparing two means
Significant difference between two means
Chi squared
Looks at difference between observed and expected
Compare to critical value
N-1 (N=number of data you are looking at)
>=significant
Explain why rate of bubbling can measure photosynthesis
More o2 oxygen bubbles released per second
Higher rate of photosynthesis and greater rate of photolysis
Paper chromatography
Pen ink would run with solvent
What is the syringe used for
Why is it more accurate than measuring bubbles of gas
Don’t put leaf in blender
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
Control experiment
If there was a colour change without solution then colour change was not because of phs
Why not shake the tubes
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
Reason for selecting specific data
Remove selective bias
Random sample
Remove bias
Transects
Measure with quadrat at intervals
Told to wipe inside of maze between experiments. Explain why?
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
Keep temperature constant
Put temperaturethermometer in
Add hot/cold water
Use water bath
Air temperature fluctuates more than liquid temperature
Why use a big sample
Large sample size to identify anomalies
Time constraints
Calculate a reliable mean
Use maggots more than once
No, may have gone a different way . Show turn alternation
Control
Set a base to get expected values
To allow comparison
Reversing maggots direction affects movement of animal
Could artificially increase results
Not reliable
Can
Go over same part
Observations
Dry and smooth/not spherical
Why repeat
To standardise results
Can compare
Get standard deviation/means
Variables for temperature
Time
Which hand used
Position of arm on surface
Why people matched for factor
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
Hydrogen carbon lit indicator
Colour change has no scale
Not impirical
No numerical value
Binary
Use colorimeter
Check light intensity
Can you get an average from two values
No, some people hold for longer
Yes,can get concordant results
Properties of co2
Forms carbonic acid with water (blow into limewater experiment)
Hand variation can you roll your tongue
D
Phenotype
Is the physical phenotype applied to organisms
Why hardy Weinberg is not applied to human populations
There is migration
Different alleles
Higher mutation rate than animals
Continuous and discrete data
Continuous-controlled by multiple alleles and environmental factors e.g.
Why plot as scatter diagram
Easier to see correlation
One variable against another
Things you
Compare
If means overlap in sd
Size of sd
If they do, no significant difference
Why do you use leaves of same plant species
Different plants have different size and length and width
Less genetic variation
Why don’t you cut the leaves
May damage shape/environment
Ethics/damages habitat
May shrivel up
True length v measured length
Harder to measure true value
Standardise to compare
Differences in standard error interpreted
When hw does not work
Why not use mark release recapture on humans
Unethical to mark humans
People don’t want to
Hard to recapture
Gel electrophoresis
Pcr
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
Spearmans rank
Association between two variables
Not necessary to get pigments out
Crushing can get pigments out
Aseptic techniques when transfers broth culture to agar plate
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
