practicals

Question 1

starch

Answer 1

iodine

Question 2

reducing sugar (e.g. glucose/all monosaccharides)

Answer 2

benedicts

Question 3

non-reducing sugar

Answer 3

hcl and benedicts

Question 4

test for proteins

Answer 4

biuret

Question 5

fats/lipids

Answer 5

ethanol and water

Question 6

result of iodine test

Answer 6

colour change from orange to blue/black

Question 7

result of reducing sugar test

Answer 7

colour change from blue to green to yellow to red/orange

Question 8

result of non reducing test

Answer 8

colour change from blue to green to yellow to red/orange

Question 9

result of biurets test

Answer 9

colour change from blue to lilac

Question 10

result of emulsion test (ethanol test)

Answer 10

white emulsion formed

Question 11

procedure of non-reducing sugar test

Answer 11

add hcl, place in water bath 90 degrees, add sodium hydrogencarbonate then benedicts

Question 12

food test for reducing sugars

Answer 12

add benedicts and place in water bath 90 degrees

Question 13

procedure of emulsion

Answer 13

add ethanol, shake, add water, shake

Question 14

what’s the equation for magnification

Answer 14

magnification = image size / actual size

Question 15

how do you calculate the actual size of something (calibration of microscope)

Answer 15

• convert stage micrometre units to nm
• convert EPU to SMU
• find out 1 EPU and convert to micrometers (mm–>micrometre = x1000)

Question 16

what is the hazard, risk and control measure in the microscope calibration practical

Answer 16

hazard: the microscope slide and coverslip are sharp is broken
risk: cuts to skin
control measure: care when using, if breakage occurs, sweep up and dispose of broken glass carefully

Question 17

explain how you would do the onion slide practical

Answer 17

• place water droplets on the slide
• take one epidermal layer of onion (using forceps)
• lay it flat on the surface of the slide
• add 3 drops of iodine
• add cover slip and lower it gently using a mounted needle (no air bubbles)
  (can also dab with a paper towel)
• then place under the microscope
  (calculate actual size of a cell)

Question 18

give 3 hazards, risks and control measures for the onion slide practical

Answer 18

1. iodine solution is an irritant, risk is contact with eyes/skin, control measure is flood with tap water if gets in contact
2. microscope slide and cover slip are sharp if broken, risk is cuts to skin, control measure is care when using so not to break
3. scalpel, risk is cuts to skin, control measure is cutting downwards and away from body

Question 19

how do you do the water potential practical (potatoes)

Answer 19

1. prepare potato cylinders with same length
2. dry each potato cylinder
3. record starting mass of each potato cylinder
4. fill tubes with different concentrations (add potato cylinder to each tube) and leave for a certain amount of time
5. remove cylinders and dry
6. record final mass and calculate % change in mass = change in mass/original mass x100

Question 20

whats the conclusion of the potato water potential practical

Answer 20

the more concentrated the sucrose solution, the more negative the mean % change in mass is

Question 21

how to do beetroot permeability practical

Answer 21

1. prepare beetroot cylinders
2. rinse to wash away pigment leakage
3. dry
4. prepare boiling tubes with distilled water
5. label each tube with different temperatures
6. place a beetroot cylinder into every tube, wait 15 mins then remove
7. place in colorimeter
8. plot a graph of mean % absorbance against temperature

Question 22

how to do the effect of temperature/pH on enzyme activity practical

Answer 22

1. place beaker of lipase solution in 25 degrees
2. place milk into a test tube and add drops of phenolthalein and sodium carbonate
3. place the test tube in 25 degrees for 10 mins then add lipase and start a timer
4. repeat for different temperatures