Paper 1 Required Particles

Question 1

5 Stages of the Microscope Practicle

Answer 1

1) Place slide on stage with clips
2) Select lowest power objective lens (4x)
3) slowly turn coarse focussing dial, objective lens needs be a almost touching slide. Look from the side to prevent damage
4) look down eyepiece and turn coarse focussing dial, increase distance between slide
5) calculate magnification (eyepiece lens x objective lens)
5) use the fine focusing to bring image into focus

Question 2

6 Stages of Effect of antibiotics on bacterial growth practicle

Answer 2

1) Get an agar plate with agar gel on a petri dish
2) Sterilise all petri dishes and agar to stop contamination
3) Sterilise the inoculation loop passing through a flame and add the microorganisms to the agar plate
4) Attach lid quickly with adhesive tape
5) add the plates with different antibiotics
5) Place Agar plate upside down into an incubator at 25c
6) Calculate area (circle) of zone of inhibition

Question 3

7 Stages of the effect of osmosis on plant tissue practical

Answer 3

1) Peel potato to get the skin and use a cork borer to produce 4 cylinder of potato with same diameter
2) Use a scalpel to trim cylinders to the same length (3cm)
3) Measure the length and mass of each cylinder on a balance
4) place into test tubes adding 10cm^3 of 0.5 then on different 0.25 molar sugar solution and on another distilled water
5) leave overnight for osmosis to take place
6) dry on paper towel to remove surface moisture and measure mass and length again
7) Calculate percentage change (actual/original then x100)

Question 4

3 Stages of Food Tests practical (part 1)

Answer 4

1) Take food sample and grind with distilled water with mortar and pestle to get paste
2) transfer paste to beaker and add more distilled water and stir to dissolve the foods
3) filter solution to remove suspended food particles

Question 5

4 Tests to see if foods are present for Food Tests practical (part 2)

Answer 5

Starch- add 2cm^3 of solution, add few drops of iodine this turns from orange to blue back

Sugars- add 2cm^3 of solution, add 10 drops of Benedict solution, put in cylinder half filled with boiled water for 5 mins and changes colour to green, yellow, or red depending on sugar content

Proteins- add 2cm^3 of solution, add 2cm^3 of biuret solution and change colour from blue to purple/pink

Lipids- 2cm^3 on unfiltered solution, ad 3 drops of Sudan III, shake gently and will see a red stained layer on top

Question 6

7 Stage of effects of Ph on amylase Practical

Answer 6

1) Place one drop of iodine solution into each well on spotting tile
2) Take 3 test tubes with 2cm^3 of Starch solution, 2cm^3 of amylase solution and 2cm^3 of pH 5 buffer solution
3) Place all 3 in water bath at 30c leaving for 10 mind
4) combine all and mix with stirring rod then return to bath and start timer
5) every 30s use stirring rod to add drops to iodine spotting tiles
6) add until iodine remains orange to see when starch is’t present and record time
7) repeat using different Ph buffers to compare

Question 7

7 Stages of Photosynthesis Practicle

Answer 7

1) Take boiling tube and place 10cm away from LED light source (less heat)
2) fill boiling tube with sodium hydrogen solution to release the CO2
3) Place pondweed into tube with cut end at the top
4) leave for 5 mins to acclimatise with conditions of the boiling tube
5) start stop watch and count number of bubbles (O2) produced in 1 min
6) repeat 2 more times to find mean bubbles or use measuring cylinder to find volume of bubbles
7) repeat whole experiment with different lengths away (20, 30, 40, 50cm) and plot graph with inverse square law as distance doubles, bubbles fall by factor 4