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Does cellulose test positive or negative with iodine solution?
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Why would a negative iodine test for starch indicate a positive result for the enzymatic degradation of starch by amylase?
Perhaps the iodine solution was old and gave a false negative.
Why did a solution of saliva and oats test positive with benedict's test and iodine test if the oats alone tested positive only in the iodine test and the saliva alone was negative for both?
polysaccharides and simple sugar
What substance is used to test for starch?
The presence of starch can be tested with the help of Iodine. Similarly Benedict's test solution is also used to detect the presence of starch.
Why doesn't cellulose give a positive iodine test?
cellulose is derived from D-glucose units, which condensed through beta(1->4)-glycosidic bond. This give cellulose to be a straight polymer therefore, it can't coil around iodine to produce blue color as starch does.
What color is gram negative stain and gram positive stain if you forget to apply iodine?
If iodine is not applied, both the gram-positive and gram-negative stains will appear to be gram-negative. The iodine acts as a mordant that helps to fix the crystal violet stain in the gram-positive bacteria, making them appear purple. Without iodine, the crystal violet stain can be easily washed out of both gram-positive and gram-negative bacteria, resulting in a pink or red color.
Is iodine a positive or negative charge?
No, nitrogen is more electronegative than iodine. Electronegativity of nitrogen= 3.04 Electronegativity of Iodine = 2.66
What solution is use to test starch?
Iodine-KI reagent. Add to the substance being tested directly. Result: If positive, Turns Blue/Black If negative, (absence of starch) Solution remains orange/yellow.
Would the iodine solution change colour when it is tested on a slice of bread?
negative
What type of food will give a negative Iodine test and a positive Biuret Solution test?
An iodine test is used to test for the presence of starch (or polysaccharides, specifically amylose or amylopectin). A Biuret solution test is used as an indicator for peptide bonds within proteins. Therefore, if you get a negative iodine test and a positive Biuret test, you would probably be testing a animal food source (beef, chicken, pork). Overall, any food that doesn't have starch present within it would be appropriate to use. Hope this helps!
What does lugol's iodine?
it is iodine and potassium iodide solution It's a orange colored solution that consists of Iodine and Potassium Iodide and is used to test a substance for starch. If the color of the solution turns black when put on/in the substance, then the substance is positive for starch.
Why do you use iodine to stain a cell?
Iodine stains starch contained in cells. Iodine is also used to distinguish between Gram negative and Gram positive bacteria. The Gram stain contains iodine.
Which colour indicate a negetive test when starch is absent?
If you're using iodine, a negative test will be the color of the iodine solution, which should be a brownish color.
