Required Practicles Paper 2 Flashcards
RP7: Reaction time- Method
Person 1 will measure the reaction time of Person 2
Person 1 sits on a stool with a good upright posture
He then places the forearm of him dominant arm across the table
Person 2 hold the ruler vertically so that person 1’s is on 0cm
Person 2 tells person 1 to prepare to catch the ruler
Person 2 drops the ruler at a random time
Person 1 has to catch the ruler with their thumb and first finger as quickly as possible
Person 2 records the measurement on the ruler that is level with the top of person 1’s thumb
The test is repeated several times and a mean is calculated
They then swap places
RP7: Reaction time-variables
IV: the person having their reaction time tested
DV: the reaction time
CV: the starting distance between the thumb and the finger, measure the ruler at the top of the thumb, lighting and background noise
RP 8: Plant Responses-light intensity method
Place cotton wool in three Petri dishes and soak them with equal volumes of water
Place ten mustard seeds in each dish
Leave the dishes in a warm place and allow seeds to germinate
Water the seeds everyday with the same volume of water
When the seeds germinate make sure each dish have the same number of seedlings
Use a ruler to measure the height of each seedling and do this while holding the stems to make sure they are straight
Place one dish in full sunlight, place the other dish in partial light, and the last dish in darkness
Measure the height of each seedling everyday for at least 5 days and record results on a table
Calculate a mean seedling height for each day
RP8: Plant responses- gravity method
A dish of seedlings is place on its side in the dark
The shoots will grow upwards against the direction of gravity
Roots have grown downwards towards the direction of gravity
RP 9: Sampling microorganisms -total population size
Use random sampling by using a quadrat
Place two tape measures 20m in length at right angles
We then need two bags and each bag contains the numbers 1 to 20
The first student removes a number from the bag and moves to that point on one of the tape measures
The second student selects a number from their bag and moves to that point on the other tape measure
The third student places a quadrat on the ground at person 1s point by person 2s point
The student records the number of daisies in the first quadrat
The students repeat this process nine more times for 10 samples
Use the equation to find the total population size:
(Total are/area sampled) x number of organisms of that species counted in sample
RP 9: Sampling microorganisms-effect of a factor on the distribution of a species
Use a transect line to see how the number of daisies changes from the tree outwards
Place a tape measure at the tree and use a quadrant to count the number of daisies at the start of the transect
Record the light intensity using a light meter
Move the quadrant one meter down the tape measure and repeat the measurements
Continue doing this all the way down the tape measure
RP 10: Decay-affect of temperature on decay of milk
Start by labeling a test tube “lipase”
Use a pipette to place 5cm3 of lipase solution into the test tube
We now label another test tube “milk”
Add 5 drops of Cresol red into the milk
Add 5cm3 of milk and 7cm3 of sodium carbonate solution to the milk test tube
The solution should be purple as sodium carbonate solution is alkaline
Place a thermometer into the test tube containing milk
Place both test tubes into a beaker of water at our first chosen temperature
Wait until the temperature of the solutions is the same as the water in the beaker
Use a pipette to transfer 1cm3 of lipase solution to the test tube containing milk and stir the solution
At the same time start a timer
Once the solution turns yellow stop timing and record the results
Repeat at a range of different temperatures
