Practicals

Question 1

Decay rate required practical

Answer 1

.First label a test tube lipase and add 5cm3 using a pipette , this enzyme used because decay is a long process and it speeds it up

.Then label a test tube milk , add 5 drops cresol red indicator and then add 7cm3 sodium carbonate, then 5cm3 milk , the solution should now go purple as its alkaline

.After this add a thermometer to the milk and then place it in a water bath at a starting temperature

.Then once the temperatures in each test tube is the same as the water , then add 1cm3 of the lipase to the milk solution using a pipette , and then stir and start a timer

.The enzymes break down the fat molecules in the milk and this causes fatty acids to be released and therefore the milk becomes acidic and in acidic conditions cresol red turns yellow , and record the time to get to this colour and repeat

Question 2

reaction time RP

Answer 2

1. Have person put arm on table with hand leaning over – reduces movement of forearm
2. Drop ruler from constant height; person should catch using thumb are forefinger
3. Record number above thumb/forefinger
4. Repeat and calculate mean distance and compare
5. Repeat all steps again but with person consuming caffeine
6. Record, average and compare results

· Ensure people tested have not consumed caffein recently or are under any influences (alcohol)
· Same hand should be used to catch
· Using a computer would provide more precise results

Question 3

plant growth response

Answer 3

1. Place 10 water seeds into three petri dishes , fixed vol with cotton wool on base , incubate in warm undisturbed place and then control amount of germinated seedlings
2. Shine light directly above one and in other directions on the other two, in
3. Leave for one week; observe plants grow towards light by measuring before and after with ruler , take care when holding them up to measure
   · Control no of seeds, type of seed, temp., water, LI
   for gravity ,

Question 4

Quadrats practical

Answer 4

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

or moving further away from somewhere , use a transect line