Practicals

Question 1

How to Uncontaminated cultures of microorganisms are required for
investigating the action of disinfectants and antibiotics.

Answer 1

• Petri dishes and culture media must be sterilised before use
• inoculating loops used to transfer microorganisms to the media must be sterilised by passing them through a flame
• the lid of the Petri dish should be secured with adhesive tape

Question 2

Osmosis in potatoes

Answer 2

Cut 3 cm long thin slices of potato (skin off) or roughly and then record lengths and mass in a table put a potato slice and 10ml of distilled water in a boiling tube do this three times
Get three different concentrations of sucrose solution and add to each boiling tube, leave for 5 mins and record results in results table

Question 3

How to find out percentage change

Answer 3

Change in mass/ initial mass

Question 4

Ph effect on enzymes, how do you know if starch still present and if starch is gone

Answer 4

Starch is present iodine solution darkblue and starch gone solution orange