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Pract Flashcards

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1
Q

Things to take note while writing tables

A
  1. Indicate +- for increase, decrease
  2. Standardise d.p.

https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 Page 1

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2
Q

decimal pt

A

reaction time - nearest second

thermometer - nearest 1dp

vol nearest 1dp

everything else to 1dp, even magnification

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3
Q

Draw line graph if got obvious outlier then

A
  1. plot (if within axes)
  2. circle
  3. label as (outlier)

https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 2

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4
Q

axes need units?

A

no.

Marking Scheme

Axis
Scale
Coordinates
Line

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5
Q

bar chart
things 2 take note

A
  1. centralise label w/ bar
  2. spaces btwn bars
  3. same bar width
  4. MUST START 0,0

https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 3

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6
Q

histogram what to take note

A
  1. X coord no need start w/ 0, Y coord MUST START 0
  2. distinct categories
  3. no data, dont plot anything

https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 4

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7
Q

Specimen Errors
g__ v__

A

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

  1. 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)

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8
Q

Specimen Errors
o__ g__ d__ e__

  1. format
  2. how2 fix
A
  1. When obtained from different organism,
  2. may have grown diff env, varying (water availability)
  3. cause inaccuracies in measurement and results (water potential)
  4. inaccuracies in final observation

obtain specimen, single organism growing similar env

Use when involve living organisms

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9
Q

Specimen Errors
s__ n__ h__

format
how2 fix

A

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

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10
Q

analyse type qns

A
  1. quote data
  2. explain data
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11
Q

application qns

A

> 1 mark -> must have link 2 syllabus

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12
Q

draw enzyme-temp graph
label optimum temp, show your thinking

A

https://docs.google.com/document/d/1sG942E4hsSUUBupFIWxzIaSQnrfX67mZtqmS5qHr5Cg/edit?tab=t.0 page 5

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13
Q

subjectivity
d__ o__ e__ p___

example
how 2 fix
format

A

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

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14
Q

surroundings errors

A
  1. confounding factors, env
  2. variability, env factors

no 1: use when investigating external factors affect rate of ___
no 2: use when investigating external factors affect rate of __

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15
Q

surroundings errors
confounding factors, env
example
how 2 fix
format

A

change instrument, add apparatus, remove confounding factor

  1. in investigating (),
  2. (what cause confounding factor)
  3. cause (variability of other variable)
  4. hence over/underestimation, inaccuracies in

i.e. place beaker, water in front of lamp, absorb heat from lamp, allow light pass thru

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16
Q

surroundings errors
variability, env factors
example
how 2 fix

A

evaporation, gravity, heat

change instrument, add apparatus, stabilise env factors

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17
Q

set-up error
example
how 2 fix
format

A

i.e. yeast gas bubbles not all collected

investigating (),
(what cause inaccuracies)
hence under/overestimation of ()

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18
Q

how improve accuracy vs improve reliability

A

accuracy
change apparatus/method
reliability
repeat expt. few times, obtain avg, omit any outliers from avg calculation

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19
Q

movement of water molecules, visking tubing
things to take note

A

error
1. visking tubing, tied, prevent leakage, liquid
2. open end, visking tubing, above liquid lvl, beaker
3. osmosis occur, when outside visking tubing was washed, distilled water
4. gravity slows down mensicus
5. evaporation, water, sucrose soln. gradually decrease conc.

use of apparatus

  1. partially permeable visking tubing, allow smaller molecules i.e. water pass thru, larger molecules i.e. sucrose cannot
  2. distance moved, meniscus/mm per minute

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20
Q

effect of conc., rate, osmosis on vegetable strip
things to take note

error
improvement

A

error
1. plant tissue, cut, identical dimension, keep sa:vol ratio constant
2. all plant tissue, submerge, liquid
3. petri dish cover, prevent evaporation
4. time each strip separately, avoid some strips submerged, slightly longer

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

  1. estimate, conc., plant cell sap
  2. intersection of graph, no net movement of water

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21
Q

caloric content of food sample (fire under food sample)
things take note

A

ensure
1. same vol, water used
2. same mass
3. food sample, complete burnt
4. stopwatch, equal time, food sample allowed, burn

error
1. heat loss, surroundings -> not all heat energy released, increase temp, water, underestimation
2. distance between food sample, flame, always different
3. ignite flame, need transfer time

prevent source of error
1. insulate wall, boiling tube, fire resistant foam
2. weigh food sample
3. leave no gap between tip of flame, hemisphere of boiling tube, ensure flame always in direct contact, glass

higher caloric content, burn larger flame, longer period time, more thermal energy released, increase temp, water, more

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22
Q

how improve reliability

A
  • repeat experiment 3x or more
  • identify outliers, exclude, calculation, mean
  • calculate mean

reduce effect outliers, increase reliability

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23
Q

how improve accuracy

A

change instrument, measurement
mercury thermometer -> data logger w/ temp probe
measuring cylinder -> syringe

improve method, measurement
change, small time intervals instead longer time intervals

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24
Q

enzymes expt. source of error

A

errors
1. pH buffer soln. 1cm^3, active enzymes, desired pH
2. bubbles may not stick, potato
3. conc. of h2o2 decrease
4. mass potato slices different, different amt o2 req float
5. temp not controlled
6. not same SA (dimensions)

improvement
1. potato tubers, diff plants
2. genetically different
3. different conc., catalase, potato discs

2h2o -(catalase)-> 2h2o + o2

catalase: many plant, animal tissues, break down hydrogen peroxide, simpler, less toxic substance

hydrogen peroxide: breakdown, produce o2, layer of froth, measure height, froth

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25
effect of (temp/pH/parameter) on rate of (enzyme) digestion expt. source of error
**iodine test error** 1. test carried out, __ minute intervals 2. could have been completely digested, any time btwn interval 3. overestimation, time taken 4. underestimation, rate, digestion **protein test error** never stir mixture **lipid test error** 1. change in colour, methyl orange indicator, gradual 2. end point not determined accurately 3. inaccuracies, measurement, time taken, digestion 4. use pH meter, indicate pH when indicator turn colourless, stop stopwatch when pH meter read exact pH **apparatus usage** **starch, iodine** extract 1 drop reacting mixture, mix w/ one drop iodine soln, time where iodine soln. no longer turn blue black, completely digested **pepsin/trypsin** protein insol. water, cloudy suspension reacting mixture clear, protein completely digested **lipase** fatty acids acidic, reduce pH methyl orange, orange -> red ## Footnote never stir mixture for test for sugar/starch e.g. involving leaf - leaves exposed to light, already photosynthesised before expt. begun
26
plant immersed in sodium hydrogencarbonate soln. light intensity expt. error apparatus sodium hydrogencarbonate soln for what?
**error** - reduce distance lamp, - increase temp, - (**place beaker of water, absorb heat energy, heat shield**) - surrounding light affect results, overestimation ## Footnote **other errors** - over time, co2 (g) used up, can be limiting factor - same no. of leaves count **apparatus** sodium hydrogencarbonate: source of co2, adjust mass, sodium hydrogencarbonate powder dissolve, more hydrogen carbonate ions
27
algal bead expt. what to count, rate of photosynthesis? what cause algal beat float? how light intensity limiting factor?
**what to count to determine rate of photosynthesis?** water plant: gas bubbles formed per unit time algal bead/leaf disc: time taken, half no., algal bead/leaf disc float **what cause algal bead float?** o2 gas released, photosynthesis, increase buoyancy **how light intensity limiting factor?** - light intensity low, light intensity limiting factor, rate of photosynthesis, - light intensity increases, rate photosynthesis increases - light intensity high, photosynthesis nvr further increase, light intensity no longer limiting factor ## Footnote limiting factor may be... **if use (aq) KMno4, can say color change subjective
28
algal bead source of error
- not all beads formed may be same mass - no stirring, suspension, not homogenous
29
destarch a plant
keep plant, dark cabinet, 48h
30
decolourise leaf, test 4 starch
- heat leaf, boiling water 5min (denature enzymes) - warm leaf, ethanol, 10min, leaf turn colourless (dissolve lipids, cell surface membrane, chloroplasts diffuse, see iodine test results clearer) - transfer leaf, warm water (soften leaf, disrupt cuticle, cell wall, easier spread out, white tile) - transfer **white tile**, iodine soln.
31
transport of dyed water, xylem expt. what dyed water used for? how water move up?
**dyed water** allow visualisation, position of xylem vessels, movement of water thru it **move up** capillary movement
32
production of co2 during respiration (germinating seeds) expt control set-up?
**control** - small pebbles, prove change in pH not due to atmospheric co2 dissolve, pH indicator - boiled seeds, prove co2 not produced, seeds dead/enzymes denatured ## Footnote muslin cloth, pH indicator
33
yeast respiration expt. (plunger submerged in water bath) source of error how does yeast respire? optimum temp?
**error** - nozzle syringe sealed, prevent gases, yeast leak out - yeast, glucose mixture submerged, thermostatically controlled water bath - no stirring, not homogenous soln - no stirring, not aerated, not enough o2, rate of aerobic respiration lower, expected **respire** anaerobically and aerobically **optimum temp** 40 deg celc like mammals
34
test urine sample for nutrients expt. healthy individual? what if glucose, proteins found?
healthy individuals: negligible glucose/protein glucose: diabetes mellitus protein: kidney disease, kidney cortex damaged, basement membrane lost integrity
35
thermometer, hot water and wrapping tissue paper around can rate of heat loss expt. source of error
**source of error** - initial temp, vol water same - freq wetting - vol water used, wetting - no heat source near ## Footnote draw tangent to curve to find gradient
36
nervous system expt. pins which part most sensitive to touch?
palm most sensitive, highest density, touch receptors, elbow least sensitive
37
blind spot expt. why dot disappear when one eye open? why dot wont disappear when both eye open?
1. image fell, blind spot, __ eye no photoreceptors 2. both eyes open,dot wont disappear, two blind spots do not coincide, image, one blind spot, fall on photoreceptors, other eye
38
cont, discont variation, use bar graph or histogram represent?
cont: histogram discont: bar chart
39
how to calculate rate of reaction
**check time** 1(0 * Ans+1 digits times)/t = Ans i.e. 100/t = 21 1000/t = 200
40
planning
1. independant variable, how adjust (range of 5) 2. dependant variable, how measure 3. 2 variables constant, how keep constant 4. repeat 3x, **calculate avg, dependant variable** 5. plot graph of __ against __ (**units**) 6. If... then... (**interpret result**) 7. bonus: shake well to mix (**suspensions,need shaking**) 8. bonus: in the dark, make sure clamp nvr cover plant (**photosynthesis**) ## Footnote **ALWAYS ADD CONSTANT VARIA**
41
planning when involve temp
put into water bath of (deg), wait for 5min ## Footnote need time for set-up to cool/heat to desired temp
42
how to improve counting bubble
connect to calibrated gas syringe ## Footnote DONT USE: DISPLACEMENT OF WATER - must explain if uw use
43
when use syringe when use cylinder
syringe: precise volumes, small volumes MC: water bath
44
sodium hydrogencarbonate + hydrilla and syringe expt. why mensicus move
- oxygen produced, photosynthesis, increase volume air, syringe - decrease pressure, liquid, capillary tube, result in movement
45
sodium hydroxide absorb co2?
yes react w/ co2
46
submerge leaf in warm water observation
- bubbles appear, both surface, leaf - warm water cause air in intercellular air spaces expand - more appear, lower surface, more stomata of leaves, lower side
47
best fit line
https://docs.google.com/document/d/1LQacTU0A416kWYxp3Du0-mVf9HBosNswJ_jQ2zTk5X0/edit?tab=t.0 page 39
48
graph paper
- each small square 1mm - draw margin of () - count squares making up, area, which occuoy more than () of squares ## Footnote measure if can
49
when to quote highest, lowest data points when to quote highest/lowest difference relative to other differences? when to quote outlier?
**highest/lowest data** - curves **highest/lowest difference** - line - describe data - must talk relative to other points - 0.6 million increase in year 1 (**largest**), but all other years 0.4million increase **outlier** - when very very off
50
cont. variation discont. variation e.gs
cont: diameter, fruit, mass, seedling discont: colour, flower
51
how prepare microscope slide
- cut thin slice - drop, iodine soln - stain sample, make it easier to see () - use cover slip, cover the slide - remove air bubbles - clean excess stain - focus lens, microscope
52
how tell something is cell wall/CSM
cell wall: double line, perimeter CSM: single line, perimeter
53
why put everything in water bath for 5 min before expt.
reach equilibrium of temp. **incubate in separate test tube
54
variables kept constant
- temperature - conc. (of soln., of indicator) - volume (no of drops, indicator) - mass - surface area - time - same (living sample, includes people) - pH - level of agitation/activity level (living) - age, species - thickness
55
variation expt. source of error
sample size small - results not representative, whole population - increase sample size same species, same age ## Footnote repeat with other plants of same species
56
accuracy for burette measuring cylinder electronic balance ruler syringe
0.05cm^3 0.5cm^3 1dp OR 2dp 1dp 1dp
57
density rate units
g/cm^3 /s
58
describe 2 ways, how you use syringe, ensure dilutions made accurately
- remove bubbles, syringe, invert syringe, tap it - use syringe, slightly larger volume
59
proper handling of apparatus
- dont cross contaminate - wash all apparatus, distilled water
60
why calculate percentage, length
- different __, different initial lengths - %tage change, accurately reflect, how much ____, shrunk, increase in size, compare how they were like, beginning
61
table first column is always
independant variable subsequent columns, dependant ## Footnote i.e. investigating how conc. of sucrose affect length of potato conc. of sucrose soln occupies first column
62
hydrogencarbonate indicator usage
usage: indicate level of co2 conc. in soln.
63
safety hazards
- ethanol: flammable - hydrogen peroxide: corrosive - acids, alkalis, indicator: irritant - hot water bath: danger of scalding - scalpel: cut
64
how improve accuracy when involving soln.
conduct expt. w/ soln. that have closer conc. to each other ## Footnote - intervals are too large - carry out expt with () conc. of (nearer intervals)
65
how to minimise safety hazard
- point test tube away when heating - use lab coat - wear goggles - wash off any split chemical - use forceps, test tube holder (**prevent indicator/chemical/hot water e.g.**) - use scalpel, stable surface, white tile - handle sample w/ forceps, avoid contact w/ scalpel ## Footnote no direct heating
66
why leave expt. at (condition except for temperature) for 5min?
Allow () to get used to (condition) ## Footnote i.e. allow hydrilla to get used to new light intensity
67
prepare solution must do...
shake mixture
68
planning involving live object
use the **SAME** ()
69
when use magnifying glass
closer look, specimens (but not cellular level)
70
how turgidity -> flexibility and describe a turgid vs a flaccid tissue
more turgid, more turgor pressure, limit movement, contents decrease flexible ## Footnote When using grid, ref **area** **turgid**: firm ,rough **flaccid**: soft, smooth
71
how improve expt. that has very close results to each other
use more time, more obv difference
72
leaf discs why rise when sucked
- force out air from intercellular air spaces - o2 produced firstly enter intercellular air spaces
73
common variables, how to adjust conc temp pH co2 conc light intensity
**conc**: dilution, add distilled water **temp**: thermostatically controleled water bath, incubation, reach same temp + acclimatisation, living organism **pH**: 1ml buffer soln **co2 conc**: mass of sodium hydrogencarbonate, higher conc. of sodium hydrogencarbonate ions **light intensity**: distance, lamp
74
how to record data (besides table, graph)
number of...
75
besides starch what else cause rise in temp of water (burn popcorn)
fats
76
data logger with (temperature probe/colorimeter/pH meter) why is better?
measure () w/o lag
77
improvement when measuring decrease/increase in something.
larger mass, larger sample size, larger starting temp
78
leaf disc / algal bead **improve** cannot determine exact time when leaf disc start rise
record time taken leaf disc reach surface, water
79
base area of beaker is large (photosythesis)
each leaf disk exposed, different light intensity
80
how range of temp too small affect result
- must repeat w/ extended range temp
81
can do nesting in bio
yes use styrofoam cup instead of beaker
82
**agar expt.** how conc/different type of agar affect
**higher conc.** -> higher rate of diffusion, underest time taken **diff agar** -> diff density, inaccuracy, rate of diffusion, slow down hydrogen ion diff.
83
source of error: stopwatch only started when...
add acid to last test tube - other test tube alr started
84
why agar expt. may not be entirely accurate for cells rate of diffusion
- different shapes - organelles slow down diffusion, increase desnity - partially permeable membrane control movement of substances
85
celery expt. SoE
**different no. of vascular tissues** - count manually, same diameter **stain move up even after expt.** conduct expt with each stalk separate ## Footnote cut longitudinaly
86
chlorophyll conc. expt why use syringe why eye level
**why use syringe** - prevent air bubbles trap **eye level** reduce parallax errors ## Footnote chloroplast suspension different conc. due to being from different plants
87
homeostasis planning
- stir contents - lid w/ hole, thermometer remain in place, measuring - equal vol ## Footnote greater starting temp
88
dilution related expt. how to improve accuracy
- conduct expt/test w/ dilutions in between () and () - check colours, compare with...
89
bicarbonate indicator improvement
- bubble gas until atmospheric co2 as indicated by (colour)
90
explain why students placed setup in a dark room
ensure lamp was the only light source, control light intensity
91
if in counting squares, it is counting a removed area or not clearly defined area
draw margins of () area
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