Required practicals- paper 2

Question 1

reaction times

Answer 1

1. 2 groups → 1 drinks water the other coffee
2. hold ruler between their fingers so they’re at 0cm
3. without warning drop the ruler
4. participant catches by squeezing fingers
5. do 3 times for mean
6. calculate mean reaction time for each group
7. square root mean drop distance and divide by 490

Question 2

plant horomones and responses

Answer 2

1. sut hole in cardboard box to allow light in
2. two petri dishes lined with cotton wool
3. scatter some cress seeds on both sets
4. wet wools with a pipette
5. one petri dish inside the box, one on top
6. water regularly for one week
7. remove and record observations

Question 3

distribution and abundance

Answer 3

1. find total area of habitat being measured
2. carefully place 0.25m2 quadrat randomly in habitat and record daisy distribution
3. multiple times in random places
4. multiply avg number of daisies in quadrat by number of quadrats that fit in the area

Question 4

rates of decomposition

Answer 4

1. 6 test tubes, 5cm3 full fat milk
2. another 6 and fill with 3cm3 lipase
3. 5 drops of phenolphthalein to milk and then 7cm3 of sodium carbonate solution (alkali) → turns pink
4. put the milk and lipase solutions in a shared waterbath (different temperatures of waterbaths)
5. once they are the same temp mix together and time for change from pink to clear