Biology, 04.08.2019 23:30, zekiyekaya0571

Asample of a white powder is given to you to identify. you can use the benedict test, the lugol test, the biuret test, and the sudan red test to identify it. if the white powder was an starch, how would each of the tests turn out

Answers: 1

Show answers

Answers

Benedicts test is used for testing reducing sugar in urine and food samples. Biuret test is used for testing proteins in a sample. Sudar Red test is used to detect lipids in a sample. For starch The Lugol test is carried out. when Lugols iodine is added to sample to the powder it will turn deep bluish black color showing the sample contain starch. The other tests will not give positive results with starch powder.

answered: AreYouMyNewDad

The test to confirm the presence of starch is Benedict's test

Explanation:

Benedict solution is used to test for simple carbohydrates (reducing sugars such as monosaccharides and some disaccharides). It has a blue colour because of the presence of copper (in the form of CuSO₄) in the benedict solution.

The white powder can be dissolved in water to make a saturated solution. When few drops of benedict's solution (blue colour) is added to about 1 ml of the white powdered solution and then subjected to heat (perhaps in a water bath), a green/yellow/orange/red precipitate will indicate the presence of starch (reducing sugar).

Biuret test is used to test for protein. It also has a blue colour which is also due to the presence of copper (in the form of CuSO₄) in the biuret solution.

When few drops of biuret solution is added to about 1 ml of the white powdered solution, there will be no colour change to violet/pink/purple which would have signified the presence of protein.

Sudan red test is used to identify/test for lipids. It has a red colour as evident from the name. It is a fat-soluble dye and would not dissolve in water. It basically stains lipids.

If few drops sudan red dye is added to the white powdered solution, the solution will not dissolve/stain the solution since it is not soluble in water.

From the above, it can be deduced that Benedict test will confirm the white powder to be starch

answered: Guest

Um can u take a picture of the work

answered: Guest

answer: carbon 14 can only be used to determine the age of the organisms that were once living, and igneous rocks are non living.

explanation:

carbon 14 dating is used to determine the age of the sample by estimating the amount of carbon 14 present in the sample and then comparing it with a reference standard.carbon 14 is a isotope of carbon which is radioactive and unstable. carbon 14 is assimilated by all plants and animals throughout their life from carbon dioxide. however, one the organisms die they stop this assimilation and the carbon 14 content starts to decrease.by knowing how much of carbon 14 is left in an organism after his death, one can estimate the age of the organism. the materials whose age can be estimated by carbon 14 method are the organic compounds. however, some inorganic compounds such as aragonite shell can also be dated.however, if we consider the igneous rocks it is a non living component which never accumulated carbon 14 in it and thus, we cannot use carbon 14 dating method to estimate its age.