Question

c: if you test a substance that has a lot of large proteins using the iodine test what would you expect to see?

• a blue to red color change
• an orange/brown to black color change
• a blue to purple/violet color change
• the iodine will remain yellow/orange since this test is not for proteins

question 7
1 pts
part 2;
d: you are trying to identify an unlabeled container of yellowish jelly - like substance from your refrigerator. it is either

• an aspic (jello type stuff made from gelatin which is solid protein ), or
• a fruit chutney (contains reducing sugar and starch), or
• a meat glaze (contains protein and starch).

you test the substance with some of the tests you learned in the lab, and the results are shown below. fill in the blanks in the table and identify the substance.

test used	result observed	explain the result
iodine	select	starch present
biuret	remained blue	select

the substance is select

Explanation:

Step1: Understand iodine - starch reaction

Iodine reacts with starch to form a blue - black complex.

Step2: Analyze Benedict's test result

Benedict's test turns red in the presence of reducing sugars. Since it turned red, reducing sugars are present.

Step3: Analyze Biuret test result

Biuret test is for proteins. Remaining blue means no proteins are present.

Step4: Identify the substance

Since there are reducing sugars and starch but no proteins, the substance is a fruit chutney.

Answer:

For question C: the iodine will remain yellow/orange since this test is not for proteins
For question D - Benedict's test explanation: Red color indicates presence of reducing sugar
For question D - Iodine test result: Blue - black (because starch is present)
For question D - Biuret test explanation: Blue color indicates no proteins present
For question D - The substance is: a fruit chutney