Experimental Design and Data

Question 1

Diffusion (non-living) practicals (not detailed)

Answer 1

• potassium permanganate in water
• methylene blue in agar
• air freshener

Question 2

Diffusion living

Answer 2

• beetroot and effect of temperature

- ⬆️ temp = ⬆️ pigment released from beetroot as there is ⬆️ KE

Question 3

osmosis non living

Answer 3

Osmometer

• visking tubing = partially permeable (water can move through membrane but glucose/sucrose cant)
• when sugar solution is in water, level rises in tube as water moves in, tube swells
• (other way around) water moves out, tube shrivels

Question 4

osmosis living

Answer 4

potato cylinder

• 0.0/0.5/1.0 sucrose solution
• % change in length

Question 5

CORMMSS

Answer 5

C - change (give values)
O - organism (details about age/gender etc)
R - repeat (3-5 x, mean)
M1 - what you measure (BE SPECIFIC units)
M2 - WHEN you measure (realistic timeframe)
S1 - biotic (living)
S2 - abiotic (non-living, temp, light intensity etc)

Question 6

investigate breathing in humans, including the release of carbon dioxide and the effect of exercise on breathing in humans

Answer 6

• hydrogen carbonate indicator (orange neutral, yellow acid, purple alkaline). shows CO2 is acidic
• limewater = shows us it is CO2

Question 7

conditions needed for germination

Answer 7

water, O2 and warmth are needed for germination (light not needed)

Question 8

VALIDITY of conclusions

Answer 8

HOW TRUE RESULTS ARE

• give arguments for and against
• look for repeats (if none, results may be anomalous
• look for controlled variables (if not comment on these)

Question 9

adapting apparatus

Answer 9

STATE WHAT EQUIPMENT IS

• how to measure -> eg scale/ruler, thermometer/water bath to change temperature
• if rate -> need stop watch

Question 10

RELIABILITY

Answer 10

• repeat and calculate mean
• similar results
• identify and discard anomalies

Question 11

VALIDITY

Answer 11

• repeats included
• variables controlled
• appropriate method (eg random/systematic)

Question 12

ACCURACY

Answer 12

• use more precise apparatus eg temp probe instead of thermometer
• do more intermediate values eg around optimum temp on enzyme experiemt
• state controlled variables

Question 13

CONTROL EXPERIMENT

Answer 13

for comparison

Question 14

controlled variables

Answer 14

• things that are kept same (so only independent variables change.)
• fair test —> valid conclusion

Question 15

QUADRATS- population size of an organism in 2 different areas

Answer 15

• random number generator = avoid bias
• quadrat (fixed size)
• sample, count number if plants per quadrat
• key to identify species
• repeat x 10 => mean number per quadrat
• multiple up for whole area

Question 16

QUADRATS- sample the distribution of organisms in their habitat

Answer 16

• transect = systematic sampling, not random
• line = sample at regular intervals on tape
• belt = use quadrat and put at regular intervals next to tape
• often linekd to environmental factor eg distance from road/stream

Question 17

SLAAPUK

Answer 17

SCALE
LINE
AXIS
AXIS
POINTS
UNITS
KEY

Question 18

what is the role of yeast in anaerobic respiration in different conditions?

Answer 18

• change temp (use water bath)
• pH (use buffer solutions)
• sugar concentration
• type of sugar eg. sucrose
• yeast concentration
• record time taken to go cloudy
• count bubbles per min
• collect gas + measure volume per minute

Question 19

destarching plant

Answer 19

• dark 24 hours

- stored starch used up in respiration

Question 20

starch test

Answer 20

• boiling water kills leaf
• boiling ethanol removes chlorophyll (ethanol flammable so use a water bath)
• warm water softens leaf
• add iodine stains starch blue black