Lab exam (med sci)

Question 1

How long to boil agar

Answer 1

1 minute

Question 2

When to pour agar

Answer 2

At 55 degrees Celsius

Question 3

Which side do you pour agar into

Answer 3

Smaller circle

Question 4

Testing for starches

Answer 4

-1-2 drops of water to well
-1 drop gram’s iodine
*Positive is blue-black

Question 5

Testing for mono/disaccharides

Answer 5

-Beaker filled half way w/ water at 80-90 degrees Celsius
-2-3mL water to test tube
-Food sample
-15-30 drops benedict’s solution
-heat test tubes for 5 minutes
*green = slightly positive
*yellow = medium
*red/brown = very positive

Question 6

Testing for polypeptides

Answer 6

-2-3 mL water to test tube
-Add sample and mix well (wash stirring rod between each)
-3 pipet squirts of biuret’s solution
-shake to mix well
-sit for 5 minutes
*pink = slightly positive
*purple = very positive

Question 7

What to record for calorimetry

Answer 7

-Water mas (50g)
-Initial temp
-Initial food mass
-Highest temp while/after burning —> final temp
-Final mass of food
-Difference in food mass
-Difference in temp

Question 8

C in calorimetry

Answer 8

4.186J/j (degrees Celsius)
or
1.0 cal/g (degrees Celsius)
*Convert final answer to kJ/kCal

Question 9

How to make table calorimetry

Answer 9

Group like value
e.g
[Temperature (degrees Celsius)]
[Initial][Final][Difference in temp]