Pract Flashcards
(27 cards)
Things to take note while writing tables
- Indicate +- for increase, decrease
- Standardise d.p.
https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 Page 1
For anything regarding reaction speed, temperature round off to wat? why?
nearest second
(reaction time est 0.3s, impossible read, nearest 0.1s)
nearest 1deg celc
smallest division, thermometer
Draw line graph if got obvious outlier then
- plot (if within axes)
- circle
- label as (outlier)
https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 2
axes need units?
no.
Marking Scheme
Axis
Scale
Coordinates
Line
bar chart
things 2 take note
- centralise label w/ bar
- spaces btwn bars
- same bar width
- MUST START 0,0
https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 3
histogram what to take note
- X coord no need start w/ 0, Y coord MUST START 0
- distinct categories
- no data, dont plot anything
https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 4
Specimen Errors
g__ v__
genetic variability
1. when obtained from different env
2. may be genetically different (diff conc. catalase)
3. cause inaccuracies in measurement and results
4. inaccuracies in final observation
obtain specimen, single organism/genetic lineage
Use when involve living organisms
- When (experiment name), (?) obtained from different (?), that may be genetically different, result different (?, e.g. conc. of sucrose), causing inaccuracies in (what ure measuring), inaccuracies (final observation)
Specimen Errors
o__ g__ d__ e__
- format
- how2 fix
- When obtained from different organism,
- may have grown diff env, varying (water availability)
- cause inaccuracies in measurement and results (water potential)
- inaccuracies in final observation
obtain specimen, single organism growing similar env
Use when involve living organisms
Specimen Errors
s__ n__ h__
format
how2 fix
Suspension not homogeneous
1. When investigating (),
2. describe how suspension is used in experiment
3. suspension may not uniform, different density/conc/? of suspension.
4. inaccuracies measurement inaccuracies, final observation
stir stock b4 using
Use when involve suspensions
analyse type qns
- quote data
- explain data
application qns
> 1 mark -> must have link 2 syllabus
draw enzyme-temp graph
label optimum temp, show your thinking
https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 5
subjectivity
d__ o__ e__ p___
example
how 2 fix
format
definition of end point
1. change instrument/add apparatus, improve def, end point
2. in investigating (), end point determined by (),
3. (change in indicator not obvious),
end pt cannot determine accurately
Use when involve indicator
surroundings errors
- confounding factors, env
- variability, env factors
no 1: use when investigating external factors affect rate of ___
no 2: use when investigating external factors affect rate of __
surroundings errors
confounding factors, env
example
how 2 fix
format
change instrument, add apparatus, remove confounding factor
- in investigating (),
- (what cause confounding factor)
- cause (variability of other variable)
- hence over/underestimation, inaccuracies in
i.e. place beaker, water in front of lamp, absorb heat from lamp, allow light pass thru
surroundings errors
variability, env factors
example
how 2 fix
format
change instrument, add apparatus, stabilise env factors
1. investigating (),
2. what caused variable factor
3. variability in other variable
hence overestimation, inaccuracies in ()
i.e. evaporation of water -> water potential decrease over time
set-up error
example
how 2 fix
format
i.e. yeast gas bubbles not all collected
investigating (),
(what cause inaccuracies)
hence under/overestimation of ()
planning
- aim/hypothesis (investigating…)
- independant
- dependant
- 3 factors, constant
- steps to be taken
- desc interpret result, record result, table, dependant variable against independant, rej null hypothesis
how improve accuracy vs improve reliability
accuracy
change apparatus/method
reliability
repeat expt. few times, obtain avg, improve reliability
movement of water molecules, visking tubing
things to take note
error
1. visking tubing, tied, prevent leakage, liquid
2. open end, visking tubing, above liquid lvl, beaker
use of apparatus
- partially permeable visking tubing, allow smaller molecules i.e. water pass thru, larger molecules i.e. sucrose cannot
- distance moved, meniscus/mm per minute
effect of conc., rate, osmosis on vegetable strip
things to take note
error
1. plant tissue, cut, identical dimension, keep sa:vol ratio constant
2. all plant tissue, submerge, liquid
3. petri dish cover, prevent evaporation
improvement
1. different plants
2. diff env
3. varying water availability
4. cell sap, tissues, diff conc.
5. inaccuracies, rate, osmosis
6. change, diameter, strips
use of apparatus
- estimate, conc., plant cell sap
- intersection of graph, no net movement of water
caloric content of food sample (fire under food sample)
things take note
errors
1. same vol, water used
2. same mass, food sample burnt
3. food sample, complete burnt
higher caloric content, burn larger flame, longer period time, more thermal energy released, increase temp, water, more
how improve reliability
- repeat experiment 3x or more
- identify outliers, exclude them, calculation, mean
- calculate mean, each data pt
reduce effect outliers, increase reliability
how improve accuracy
change instrument, measurement
- data logger, temperature probe more accurate, mercury thermometer
- syringe more accurate, measuring cylinder
improve method, measurement
- change over small time intervals instead longer time intervals
