working scientifically Flashcards
(62 cards)
1
Q
what is it called when you read the measurement not at eye level
A
parallax error
2
Q
how to overcome parallax error
A
use a digital measurer to get reading from a display
3
Q
what is it called when results vary randomly
A
random error
4
Q
examples of random error
A
- use equipment wrong
- misread reading
- reaction time eg stopwatch
- change in room temperature
5
Q
how to overcome random error
A
take more measurements and calculate mean
6
Q
what is it called when results vary consistently
A
systematic error
7
Q
examples of systematic error
A
- consistently use wrong conc
- different measuring device used e.g a different thermometer
- zero error
8
Q
how to overcome systematic error
A
- do experiment from scratch using different technique or equipment, then compare with original to see if systematic error did occur
- add/subtract inaccuracy from group of readings
9
Q
what is it called when a reading on equipment does not start at zero
A
zero error
10
Q
example of zero error
A
faulty thermometer - shows -10°in ice water
11
Q
how to overcome zero error
A
- record zero error when nothing is being measured
- subtract/add value of zero error
12
Q
prescision meaning
A
how small the range is surrounding the mean value
13
Q
7what errors can you evaluate using precision
A
random - they do not say whether data is accurate eg zero error
14
Q
how to find uncertainty
A
range/2
15
Q
how to write range
A
min value - max value
16
Q
repeatable meaning
A
measurements from when an experiment is repeated under the same conditions to get similar results
17
Q
reproducible meaning
A
measurements produced from different investigators with different equipment, with similar results
18
Q
G standard form
A
10^9
giga
19
Q
M standard form
A
mega
10^6
20
Q
k standard form
A
10^3
21
Q
d standard form
A
deci
10^-1
22
Q
c standard form
A
centi
10^-2
23
Q
m standard form
A
milli
10^-3
24
Q
upside down h standard form
A
micro
10^-6
25
n standard form
nano
10^-9
26
independent vs dependent vs control
independent: changes
dependent: measured
control: stays the same
27
what variable is room temp
control: however it is difficult to keep the same, so monitor temp with a thermometer
28
what is peer review
where other scientists check results and explanations before published, to validate and detect false claims
29
how are theories made
- hypothesis created from observations
- gather evidence from investigations to test hypothesis
- peer review, other scientists create own predictions and experiments, and repeat original experiments
- all evidence supports: accepted
- unexplainable result: modify or scrapped completely
30
issues with the media
not peer reviewed, over-simplified, inaccurate, biased
31
issues of scientific developments
economic: eg expensive alternate energy source
social: eg fossil fuel tax
personal: eg local wind farm
environmental: eg dam construction
ethical: eg genetic engineering
32
how to decide how hazardous something is
- chance of hazard occuring
- seriousness of hazard
33
what is resolution
smallest change of measuring instrument
34
examples of hazards
- microorganisms
- chemicals
- electricity
- fire
35
causes of correlation
- chance
- unaccounted 3rd variable
- change in one variable causes a change in another eg age,smoking and lung cancer
36
what to consider when evaluating
- method and controls
- multiple, repeatable, reproducible, accurate, precise results?
- anomalies and errors than caused them
- suggest change
- suggest further experiments
37
ionic equation meaning
only shows ions involved
38
different ways to heat something
bunsen burner
electric heater
water bath
39
why does a singular measurement not prove the precision of readings
repeat reading needed to show results are close together
40
what is not an independent variable
time intervals between recordings
41
precise meaning
results show little variation
42
how to show that two things are directly/indirectly proportionate on graph
find constant
statement *** x/ *** = constant
and give three examples
43
how to convert tonnes to kg
x 1000
44
when investigating effect of one factor, how can you change investigation to investigate another factor
- keep first dependent variable (first factor) constant
- then alter new dependent variable (new factor)
- test range of values of new variable
45
factors to control when investigating a sample of people
- gender
- age
- no health issues
- number of people (min 5)
- intensity of test
- obesity
- smoking/drinking
- diet
- medication/drug use
- family history of disease
- fitness level
-
46
what can cause data to be considered valid
- large sample
- long term sample
- many controls
- peer review
47
what can reduce validity of data from investigation of a large sample of people
- people may not be honest
- people may over/under estimate
- people may change (habit/variable) over time
- timing may be different for each subject
48
why are small animals tested on
cheap
easy to breed
49
when making a conclusion from data what measurements should you compare
percentages
50
when calculating from a table what measurements should you not use
percentage
- use percentage when making conclusion
- question asks number of stomata in (area) for 0.4 mol/dm3, use 4/area, not percentage of area
51
how do guard cells open stomata
- water moves into guard cell via osmosis
- inner wall is less flexible than outer wall as it is thicker, meaning it swells unevenly, causing stomata to open
52
how do ions moving into guard cells cause them to open
- more ions = decrease concentration of water
- water moves in via osmosis
- inner wall is less flexible than outer wall as it is thicker, meaning it swells unevenly, causing stomata to open
53
why is too many stomata bad
- more water lost
- plant will wilt (collapses as cells are not full of water, so cell wall can no longer support the plant
54
why are there fewer stomata in high co2 conc
more co2 so not as many stomata needed to obtain amount of co2 needed
55
what actually is stomata
the pore (gap) that controls water loss (vapour) and gas exchange
56
how to describe trends in tables with two categories eg men and women
compare seperately
57
how to present data with more validity if categories are different eg female population and male population
show percentages
show per 100 000
58
why might media be biased
financial gain/competition
59
why is a mean imporant
reduce random error, closer to true value
60
why do you leave time before recording temperature after turning heater on
so reading is same as temperature of heater
61
why can you not change two variables in an investigation
cant see effect of one
62
cause of anomalies in transformer investigations
too few/many coils
