practicals

Question 1

what is the process to do the antibiotics core practical

Answer 1

-spread bacteria culture on agar plate
-place antibiotic disc and negative control disc
-incubate
-measure the zone of inhibition and calculate effectiveness

Question 2

what are the asceptic techniques when doing the antibiotics core practical

Answer 2

-sterilise using alchahol and flame
-work under bunsen burner
-sanitise surface
-use autoclave to sterilise equipment

Question 3

what is a hypertonic solution

Answer 3

this is a highly concentrated solution

Question 4

what is an isotonic solution

Answer 4

this is an equally concentrated solution

Question 5

what is a hypotonic solution

Answer 5

this is a low concentration solution

Question 6

how do you do the osmosis practical

Answer 6

-measure the initial mass of potato strip
-place each strip in different concentrations
-remove them after a certain time and dry them
-measure final mass
-calculate mass change

Question 7

what are the controls in the osmosis practical

Answer 7

-potato strips must be the same size
-volume of the solution must be same
-age of potato must be the same
-amount of time it was in solution

Question 8

how do you do the practical for the effect of pH on enzyme activity

Answer 8

1)drop one drop of iodine into each “well” in the dimple spotting tile
2) use a gas syringe to transfer 2cm3 of amylase to a test tube
3) add 1cm3 of your chosen pH into the same test tube
4) note the pH
5) add 2cm3 of starch solution to the same test tube
6) start the stop clock for 20 seconds
7) add a drop of mixture into first well of iodine
8) after 10 seconds if remains blue-black, add some to the next well
9)record when the colour is no longer blue-black
10) repeat with different pH

Question 9

how do you test for starch

Answer 9

1)place one spatula of powdered food on a spotting tile
2)place a few drops of iodine solution onto food powder
3) if it turns blue-black, starch is present

Question 10

how do you test for protein

Answer 10

1) place a spatula of the powdered food in a test tube
2) add 1cm3 of water and mix
3) add biuret solution and stir
4) if it contains protein, it will turn purple

Question 11

how do you test for lipids

Answer 11

1) place a spatula of powdered food in a test tube
2) add 2-3cm3 of ethanol
3) place a bung and shake
4) pour liquid from the top of the mixture into a boiling tube half filled with water
5) if it turns cloudy, lipids are present

Question 12

how do you test for reducing sugars

Answer 12

1) place a spatula of powdered food into bioling tube
2) add 1cm3 of water and 1cm3 of benedicts solution and mix
3) place them in a water bath at 70 degrees
4) if reducing sugars are present, colour turns orange-red