Required Practicals

Question 1

B1: Microscopes

Answer 1

-set up microscope
-observe
-draw + label eg of animal cells and plant cells
-always show scale of magnification on drawings

Question 2

B1: Osmosis basis of experiment

Answer 2

-to put plant tissue into diff concentrations of salt/sugar solutions

Question 3

B1: Osmosis - results

Answer 3

• hypotonic solution = water moves in
  -hypertonic = water moves out
  -measured by effect on tissue sample

Question 4

B1: microscopes safety (4)

Answer 4

-careful when handling glass slides
-avoid iodine on skin
-wear eye protection
-don’t break slide by moving objective lens too far downwards

Question 5

B1: microscopes equipment (5)

Answer 5

-light microscope
-microscope slide and cover slip
-samples
-dilute iodine solution
-dropper pipette

Question 6

B1: microscopes method (5)

Answer 6

-collect sample of cell
-remove inner skin layer of onion
-place thin slice onto glass slide
-add two drops of iodine onto sample
-lower cover slip onto slide so liquid spreads out

Question 7

B1: Osmosis safety

Answer 7

-careful when handling sharp knives

Question 8

B1: Osmosis equipment (9)

Answer 8

-plant tissue
-range of concentrations of sugar/salt solutions
-distilled water
-apple corer
-sharp knife
-white tile
-filter paper
-boiling tubes
-measuring cylinder

Question 9

B1: Osmosis method (7)

Answer 9

-cut plant tissue + place in tile
-place tissue in range of solution 1-5
-measure starting mass of sample
-leave sample in solution for at least 20 mins
-remove samples and dab dry
-measure ending mass
-calculate percentage mass change + plot graph

Question 10

B3: Food tests safety

Answer 10

-biuret solution is corrosive
-wear eye protection
-gloves

Question 11

B3: Food tests - carbohydrates starch

Answer 11

-iodine test
-yellow to black

Question 12

B3: Food tests -carbohydrates sugar

Answer 12

-benedict’s solution with a heat bath
-blue to red

Question 13

B3: Food tests - proteins

Answer 13

-biuret test
-blue to purple

Question 14

B3: Food tests - lipids

Answer 14

-ethanol - highly flammable/harmful
-clear to cloudy

Question 15

B3: Effect of pH on rate of reaction on enzymes - safety (2)

Answer 15

-wear eye protection
-avoid contact with iodine on skin

Question 16

B3: Effect of pH on rate of reaction on enzymes - equipment (8)

Answer 16

-amylase solution
-starch
-iodine
-buffer solution
-syringes
-pipette
-spotting tile
-water baths

Question 17

B3: Effect of pH on rate of reaction on enzymes - method (8)

Answer 17

-place 2cm3 of amylase into test tube
-add 1cm3 of buffer solution too
-place tube in water bath
-add a drop of iodine in each dimple of spotting tile
-after 5 mins add starch to amylase solution
-after 30 secs add one drop to iodine tile
-repeat with diff pH buffer
-record results/time taken

Question 18

B5: effect of antibiotics on bacteria - equipment (6)

Answer 18

-bunsen burner
-filter paper discs
-disinfectant
-agar plate
-disinfectant solution
-sterile forceps

Question 19

B5: effect of antibiotics on bacteria - method (5)

Answer 19

-Wash your hands and surfaces
-work close to bunsen burner - kills pathogens in air
-using forceps = dip disc A into antibiotic A etc
-Dry and place in agar gel - tape lid
-store dish upside down and incubate

Question 20

one of inhibition calculation

Answer 20

πr 2, where r is the radius of the zone of inhibition .