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Why glucose does not give positive result with iodine test but not starch?
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.
Is glucose expected to have a positive iodine test?
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.
How starch can give a negative iodine test?
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.
Which reacts to iodine glucose or starch?
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)
When multiplying two numbers with different signs the result will be?
Multiplying a positive and negative number will give a negative result. The result is a negative number.
Do proteins give positive iodine tests?
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.
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?
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.
What are positive and negative controls in an experiment?
Positive controls : an experimental treatment that will give the desired result Negative controls: An experimental treatment that will NOT give the dersired result.
Would glucose give a positive result with the Biuret test?
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.
Do glucose give a positive result for anthrone test?
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.
Can drinking too much water give a negative result for infection?
No
Why doesn't the cellulose give blue color with iodine?
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.
