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Bio A2 Level > Paper 5 > Flashcards

Paper 5 Flashcards

1
Q

2 calculations to do T test

A
  • Mean
  • SD
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2
Q

T test key phrases

A

-when comparing means of 2 sets of data/continous/quantative data
- If T value is GREATER than critical value, results are sig and NOT due to chance
- go with larger degree of freedom if its a range e.g if DOF is 19 and table range is 18-20, take 20

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3
Q

Degrees of freedom

A
  • N-1
  • if theres 2 samples then (n-1) + (n-1)
  • n= number of samples
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4
Q

Data needed to calc SD

A
  • Number of samples
  • Mean value
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5
Q

SD key phrases

A
  • spread of data from mean value
  • larger the value = less reliable results
  • if spread of data around mean is NARROW spread = more reliable than wide sp
  • Overlapping= no sig diff between means
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6
Q

Chi squared test

A
  • Shows data is discrete/discontinous
  • if chi sq value SMALLER than critical value at 0.05 theres is NO sig diff + results due to chance+ accept null
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7
Q

Standard error, Sm key phrase

A
  • SE = *calculate confidence limits + indicates how certain you can be that the “true” mean lies within the range of est mean sample *(like guessing the average height of all students in a school by measuring just a few. The SE tells you how good your guess might be. If the SE is small, your guess is likely to be very close to the true average height. If it’s large, your guess might be off)
  • Measure of accuracy of calculated mean value/closeness of sample to actual mean
  • The larger SE= less reliable the value
  • A close sample mean = shows results are close to actual mean
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8
Q

Error bars

A
  • If SE bars DON’T overlap = diff between samples, results are SIG and NOT due to chance
  • If SD values/SE bars overlap= no sig diff between data + due to chance
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9
Q

Spearmans correlationn use

A
  • If data NOT normall distributed
  • Data points indepent of each other
  • data can be converted to ordered data
  • if value closer to 0 = weak pos correlation between distribution of 2 species.
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10
Q

Pearson correlation

A
  • data collected is continous/normal distributed/linear
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11
Q

Microscope

A
  • Magnification of x400
  • use EPG
  • calibrate eye piece w stage micrometer
  • find value in mm of EPU
  • CONVERSION OF MM/EPU TO UM
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12
Q

PLANNING AN EXP

A
  • IV and how to vary it
  • DV and how to measure
  • 2 control V’s
  • What is the control e.g light vs no light
  • Risk, low/med/high and how to prevent injury
  • Reliability/repeats + stats test
  • Accuracy- range of solutions
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13
Q

If asked about inaccuracy

A
  • insufficent data
  • narrow range of conc w smaller intervals within range
  • more conc/temps
  • have control so comaprison can be made
  • inconclusive results if NO stats test carried out
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14
Q

CO2

A
  • Usually, most of the CO2 absorbants are with -OH eg: NaOH or KOH
  • Sources of CO2 are CaCO3, H2CO3
  • a non-chemical source: gas cylinder
  • the gas is supplied through a bubbler.
  • to measure CO2 concentration: use probe with meter/gas syringe
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15
Q

Measuring:

A
  • use mm calipers
  • a ruler- calibrated to cm or mm
  • measuring cylinders
  • syringe, pipette
  • weighing scale/ electronic balance
  • digital/mercury thermometer
  • MEASURING PLANT LENGTH
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16
Q

MOVEMENT AND TIME

A
  1. measure distance moved at a certain time (or)
  2. measure time taken for certain distance moved
17
Q

Control:

A
  • in an exp with living organisms, the control must be a dead organism
  • whatever factor is being used in the question is emitted from the control
  • For counting chromosomes and making them visible, the growing regions of the plant are cut
  • cut surface of the specimen
  • chromosomes are counted by placing cut surface under a high power light microscope(with high magnification)
  • How to make chromosomes visible?
  • > add dye/stain them
18
Q

outline how colorimters should be prepared before carrying out measurements

A
  1. calibrate colorimeter / set colorimeter (absorbance) to zero ;
  2. use distilled water (to, calibrate colorimeter / set to zero) ;
19
Q

for risk assesment what are the things you MUST state

A
  • the hazard e.g knife or reganet
  • the risk e.g injury/irritant etc
  • precaution e.g cut away from hand/wear gloves
20
Q

suggest why results of the exp should not be interpetredt as FINAL

A

1 investigation only, carried out once / not repeated ;
2 investigation only on one crop species
3 investigation only investigated, one / two, gene
4 investigation only, in one geographical area ;
6 no long-term data / no data over several generations ;

21
Q

CORMMS abt stomatal density

A
  • method of, random / systematic sampling of plants ;
  • (take leaves) from same species, that is present in both habitats ;
    -collect a minimum of 5 leaf samples (in both habitats) ;
    -same position / age, of leaf (on plant) ;
  • impressions to be taken from, lower / upper / both / same, surface(s) (of leaves) ;
  • (impressions viewed using) same, magnification / lens / size of field of view ;
    -count stomata (in field of view) ;
  • details of systematic counting / count only whole stomata / take a photograph and mark ;
22
Q

why extract fecal matter sample instead of plasma sample

A
  • no invasive
  • can be collecetd remotly
  • doenst harm organism
  • no risk if infection
23
Q

how to seperate liquid from solid

A
  • make suspension/liquidy X
  • centrifuge/filter to remove solid
24
Q

null hypothesis for chimps life expactcy w SIV and w/o SIV

A

no difference between the, life expectancy between SIV+ and SIV-

25
Q

explain whats meant by p<0.05

A
  • probability / it, is where null hypothesis is rejected ora ;
  • less than, 0.05 / 5% / 5 in 100, probability that the, result / it, is not significant / is due to chance ;
  • more than, 0.95 / 95% / 95 in 100, probability that the, result / it, is significant / is not due to chance
26
Q

how to calc percentage change

A
  • initial-final/inital x 100
27
Q

define percentage density

A
  • number of X per unit area
28
Q

Dilution formula: C1V1= C2V2

A

C1= Concentration of the stock solution (6.0%)
- V1 = Volume of the stock solution to use
- C2 = Desired concentration of the final solution
- V2 = Final volume of the solution (50 cm³)

29
Q

How to know if reuslts are sig or not

A

If the p-value is less than 0.05, = results are significant.
- reject the null hypothesis,
- not due to chance

30
Q

suggets why scientist calculated a 95% confidence interval

A
  • to get a measure of how close the, calculated /, mean is likely to be to the, true mean
  • if no overlap of error bars the results sig and vice versa
  • shorter, error bars show true mean is likley to be closer to the calculated mean

Bio A2 Level (8 decks)

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