Glucose does not give a positive result with the iodine test because iodine specifically binds to the helical structure of amylose, a component of starch, forming a blue-black complex. Glucose, being a monosaccharide, does not possess this helical structure, and therefore does not interact with iodine in the same way. In contrast, starch, which is a polysaccharide made up of multiple glucose units, presents the necessary structure for the iodine to react and produce a visible change.
Yes, glucose is expected to give a positive iodine test. Iodine reacts with glucose to form a blue-black color, indicating the presence of reducing sugars in the sample.
Starch can give a negative iodine test when starch is mixed with iodine in water. The iodine gets stuck in the coils of beta amylase molecules and the starch forces the iodine atoms into a linear arrangement in the central groove of the coil.
Starch turns blue when Iodine is introduced. Added: Though it's not quite a chemical reaction, Iodine will give starch a bluish purple color but it stays chemically UNchanged. Iodine stays reddish brown with glucose and many other oligosaccharides (up till about 10 to 15 monomeric glucose units)
Multiplying a positive and negative number will give a negative result. The result is a negative number.
Yes, proteins can give a positive iodine test. When iodine reacts with proteins, it forms a complex that results in a brown color change, indicating a positive test for proteins.
Saliva contains the enzyme amylase which breaks down starches in oats into simple sugars like glucose, which can then react with Benedict's solution to give a positive test result. The iodine test detects the presence of starch, which is in oats but not in saliva, explaining why the combination tested positive in both tests.
Positive controls : an experimental treatment that will give the desired result Negative controls: An experimental treatment that will NOT give the dersired result.
No, glucose would not give a positive result with the Biuret test. The Biuret test is specific for detecting proteins, not sugars like glucose. It works by reacting with peptide bonds in proteins to form a colored complex.
Yes, glucose gives a positive result for the anthrone test. The anthrone reagent reacts with the carbohydrates present, including glucose, producing a blue-green color that can be detected spectrophotometrically.
No
Cellulose does not give a blue color with iodine because it is a polysaccharide composed of glucose units linked together by beta-1,4-glycosidic bonds. Iodine reacts with the helical structure of starch, forming a blue-black complex due to the presence of amylose chains. Cellulose lacks the necessary structure for this reaction to occur.