Paper 2 RQPs

Question 1

what is the aim of the reaction time practical?

Answer 1

investigate the effect of a factor (e.g. caffeine, background noise, practice) on human reaction times

Question 2

what is the equipment list for the reaction time practical?

Answer 2

ruler
chair
table

Question 3

describe the method for the reaction time prsctical?

Answer 3

Work with a partner. Person A holds out their hand with a gap between their thumb and first finger. Person B holds the ruler with the zero at the top of person A’s thumb
Person B drops the ruler without telling Person A and they must catch it.
The number level with the top of person A’s thumb is recorded. Repeat this 10 times.
Swap places, and record another 10 attempts.

Question 4

what are some sources if error in the reaction time practical?

Answer 4

participants may be practised in this task; sample size may be too small to make a valid conclusion

Question 5

what is the aim of the plant responses practical?

Answer 5

investigate effect of light/gravity on growth of seedlings

Question 6

describe the equipment list for the plant responses practical

Answer 6

White mustard seeds
Petri dishes, cotton wool, water
Ruler
Window with exposure to light, dark cupboard

Question 7

describe the method for the plant responses practical

Answer 7

Put cotton wool into 3 petri dishes, and add same volume of water to each
Add 10 seeds to each and place in a warm place
Allow seeds to germinate, and add more water if cotton wool dries out.
Once germinated, ensure petri dishes each contain same number of seeds; remove any extra seeds if necessary.
1 petri dish will sit in full light on a windowsill; 1 will be in a dark cupboard; 1 will be in partial light.
Every day for 1 week, measure height of each seedling and record the results
Calculate mean of seedlings each day and plot a graph of ‘mean height of seedling’ against ‘day’

Question 8

what are some error sources for the plant respnses practical?

Answer 8

seedlings in the same petri dish may not experience the same exposure to light; sample size for each environmental condition may be too small; temperature may be another factor

Question 9

what are the safety precautions for the plant responses practical?

Answer 9

seeds may be a biohazard - wash hands after handling

Question 10

what is the aim for the field investigation practical?

Answer 10

to use random sampling to estimate population size of a plant species. To use continuous sampling to investigate effect of variation in a factor on distribution of species.

Question 11

what is the equipment list for the field investigation practical?

Answer 11

Frame quadrat (25cm x 25cm)
Tape measures
Clip board, pen, and paper

Question 12

describe the method of random sampling

Answer 12

randomly generate 2 numbers to be used as coordinates to find a location on the 2 tape measures set up
Set down quadrat at coordinates
Count and record number of required plants in quadrat
Repeat 1-3 to take 9 more samples
Estimate population size [area sampled / total area * number of plants counted]

Question 13

describe the method of line transect sampling

Answer 13

Lay a tape measure along a location with an ecological gradient
Place quadrat along ‘0’ end of tape, with 1 corner touching ‘0’ mark
Count number of plants and record
Repeat 3 at 5m intervals until reach end
Repeat nearby along same gradient and find mean no. plants at each point along transect
Plot a graph for ‘no. plants’ against ecological gradient

Question 14

what are some error sources for the field investigation practical?

Answer 14

without repetitions, results from only 1 transect may be anomalous and unreliable

Question 15

what is the aim of the decay pracxtical?

Answer 15

investigate effect of temperature on rate of decay of fresh milk by measuring pH change

Question 16

what is the equipment list for the decay practical?

Answer 16

Full fat milk
250cm3 beakers
Marker pen
Thermometer
pipette
pH indicator
incubator

Question 17

describe the method of the decay practical

Answer 17

Place 20 cm3 of fresh milk into 3 beakers
Decide the three temperatures you will investigate. Write these onto the sides of the beakers.
Use universal indicator to determine pH of the milk in the beakers
Cover each beaker in cling film and incubate at appropriate temperature
Use universal indicator paper or solution to determine the pH of the milk in the three beakers after 24, 48 and 72 hours

Question 18

what are the results for the decay practical?

Answer 18

As milk decays its pH reduces because bacteria present in milk carry out a chemical process to provide them with energy. This process converts lactose sugar in the milk to lactic acid, and producing this acid reduces the pH of the milk.