P2- Required Practicals

Question 1

1) Reaction time

Answer 1

1. Sit down, place forearm of weaker hand on table with hand hanging over the edge of table
2. Have partner hold ruler with bottom end in between your fingers so you can practice holding the ruler with 2 fingers
3. Have partner hold ruler and remove your fingers
4. Have partner hold ruler in line so the 0 mark is level with top of your thumb
5. Partner drops ruler not saying, catch ruler as quick as you can
6. Record number level with top of your thumb after you catch ruler in a table
7. Repeat 5 times and then swap with partner
8. Find reaction times using conversion table

Question 2

2) Plant responses

Answer 2

1. Pour fixed volume of water in 3 petri dishes, add cotton wool
2. Place 10 seeds in each petri dish
3. Place dishes in warm location (incubator) not to be disturbed
4. Allow time for seeds to germinate
5. If not all seeds have germinated into seedlings remove excess ones so all dishes have the same number of seedlings
6. Place 1 dish in full sunlight by a window, place 2nd in partial sunlight and 3rd in darkness in a cupboard
7. Use ruler,measure height of each seedling every day for 1 week
8. Record in table, find mean height each day, plot a graph

Question 3

3a) Field Investigation/Quadrats (A)

Answer 3

1. Use random generator to get 2 numbers to be used as coordinates to find a location on 2 tape measures set up
2. Set down the quadrat at the coordinates
3. Count and record number of required plant species in quadrat
4. Repeat 1-3 to take 9 more samples
5. Estimate population size using equation: area sample/ total area x number of plant species counted

Question 4

3b) Field Investigation/Quadrats (B)

Answer 4

1. Write down a hypothesis of the effect of a change in an abiotic factor (eg light intensity) on the distribution of the plant species
2. Lay down tape measure from base of a tree to open area of ground
3. Place quadrat along ‘0’ end of tape measure, with one corner touching ‘0’ mark
4. Count number of plants and record in a table
5. Place quadrat 5m up tape measure and repeat s3
6. Repeat s4 at 5m intervals until you reach end of transect line
7. Gather data, find mean number of plants at each point along transect
8. Plot a graph and compare results to hypothesis

Question 5

4) Decay

Answer 5

1. Write down hypothesis for the effect of temperature on rate of decay of milk
2. Fill 1/2 of beaker with hot water from kettle or water bath
3. Transfer 5cm3 lipase solution into boiling tube using syringe
4. Add 5 drops of phenolphthalein into another tube, label ‘milk’
5. Use pipette to transfer 5cm3 of milk into ‘milk’ tube
6. use another pipette to transfer 7cm3 sodium carbonate solution to ‘milk’ tube to make purple/pink solution
7. Place thermometer into ‘milk’ tube
8. Place both boiling tubes into water bath
9. Give time for solutions in tubes to reach same temp as bath
10. Use new pipette, transfer 1cm3 lipase from ‘lipase’ tube into ‘milk’ tube and start timer immediately
11. Record time required for colour change to white in a table
12. Repeat at same temp twice to record a mean
13. Repeat at different temps and plot a graph of time against temperature