Lab 2 bio PDF

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Exercise 1 1. The specifics of positive and negative controls must reflect the experiment. What would be the simplest positive and negative controls for a Benedict’s test experiment? - Positive control contains the variable for which you are testing. The negative control does not contain the variable for which you are searching Tube 1 2 3 4 5 6 7

Tube Onion juice Potato juice Sucrose solution Glucose solution Distilled water Reducing sugar solution Starch solution

Colour Orange red Green Blue Orange red Blue Orange Blue

3. What was the purpose of testing water? To see the cleanliness of the water and make sure there are no particles in the solution 4. Would you predict all monosaccharides to react with Benedict’s reagent? Why or why not? Yes all monosaccharides react with benedict’s reagent since they are considered reducing sugars for having a free aldehyde and a free ketone group 5. Would you expect all polysaccharides to react? Why or why not? No not all polysaccharides react with benedict’s reagent because not all of them have free aldehyde or a free ketone group Exercise 2 Tube 1 2 3 4 5 6 7

Tube Onion juice Potato juice Sucrose solution Glucose solution Distilled water Reducing sugar solution Starch solution

Colour Yellow Blue -black Yellow Yellow Yellow Yellow Blue-black

How would you predict that an onion stores its carbohydrates? What expected result from a Benedict’s and Iodine test would support your prediction? - Carbohydrates are stored as a reducing sugar in onions since they tested positive for the Benedict’s reagent test (orange-red) and negative for the iodine test (yellow) How would you predict that a potatoes stores its carbohydrates? What expected result from a Benedict’s and Iodine test would support your prediction? - Carbohydrates are stored as starch in potatoes since they tested very low levels of sugar for the Benedict’s reagent test (Green) and positive for the iodine test (blueblack)

Exercise 3 1. What would be the simplest positive and negative controls for a Biuret test experiment? - Using Egg albumin as the positive control for a Biuret test since it tests positive showing a purple colour and distilled water as the negative control for the Biuret test since it test negative showing a blue colour Tube 1 2 3 4 5

Solution Egg albumin Corn syrup Amino acid Distilled water Protein

Resultant colour Violet Purple Purple Blue Purple

Which would you predict would have more peptide bonds, egg albumin or corn syrup (honey)? What expected result from a Biuret test would support your prediction? - Egg albumin since it has a more intense colour than corn syrup when using the Biuret test Exercise 4 1. Describe the meaning of the term solubility? - solubility the ability for the solute to dissolve in a solvent Tube Solution 1 Salad oil + water 2 Salad oil + Sudan IV 3 Corn syrup + Sudan IV 4 Distilled water + Sudan IV 5 Lipid + Sudan IV

Resultant colour Orange Red Orange Orange Red

3. Which of the solutions was the negative control? Which was the positive control? - salad oil + Sudan IV was the positive control and distilled water + Sudan IV was the negative control 4. Which other substance listed in the table above would you expect to show a positive reaction? - lipid + Sudan IV . Lipids supply more than twice as many calories per gram as do carbohydrates. Which would you predict would contain contains more calories, oil or corn syrup (honey)? What expected result from a Sudan IV test would support your prediction? - Oil contains more calories than honey since salad oil tested positive when mixed with Sudan IV (red) whereas the corn syrup when mixed with Sudan IV turned out negative (orange) Exercise 5 Tube 1 2 3

Solution 2 ml DNA 1 ml DNA + 1 ml water 2 ml water

Colour Blue Light blue No colour

From the video, what other types of tests can be done to support the presence of DNA in a solution? Are these other tests as effective as the Dische diphenylamine test for identifying the presence of DNA? Why or why not? -

You can use a phosphate test, which isn’t as reliable as the Dische diphenylamine test since the sugars in both DNA and RNA have a phosphate group which doesn’t eliminate that it could be an RNA solution rather than a DNA solution...