Life Science(Biology)

Detection of Fe from the HCl extract of Plant Ash solution  Presence of Fe(lll) ions is determined by Thiocyanate Test.    Principle:-   It is a very sensetive test in which Fe(lll) ions convert to Fe(ll) ions when treated with Thiocyanate ions/ (SCN)- . Experiment  Observation  Inference To about 10 ml of HCl extract of Plant Ash solution , a drop of 5% Ammonium Thiocyanate is added. The solution turns blood red immediately. Blood red colour is formed due to the foation of a compound by Fe(ll) ions.   So, Fe is present in the given solution. Reaction: Fe(H2O)63+ + (SCN)- (aq) →Fe(SCN)(H2O)52+ Test 2 Experiment: 2 ml of acidic solution is heated in a test tube, to it 2% potassium ferrocyanide soln. is added. Observation: A purplish blue ppt. appears due to the formation of ferric ferrocyanide complex. Inference: Fe present in the given acid solution. Reaction: Fe(3+) + K4[Fe(CN)6]3-->Fe4[Fe(CN)6]3 +4K(+)

  Detection of Magnesium in HCl extract of Plant Ash General Test   To detect Mg from  an unknown sample Disodium Hydrogen Phosphate test is performed. Experiment  Observation  Inference  To about 20 ml of HCl extract of Plant Ash filtrate a drop of dil.NH4OH is added to make the solution alkaline.  The mixture is heate for 2-5 minutes and then cooled.     Finally 10% Disodium Hydrogen Phosphate is added to it. A white ppt is formed.The ppt is of insoluble Ammonium Magnesium Phosphate. Mg is present in the solution. Reactions:- MgCl2+Na2HPO4+NH4OH →Mg(NH4)PO4 (white ppt) + 2NaCl +H2O       Or, MgSO4+ Na2HPO4 + NH4OH → Mg(NH4)OH (white ppt) + Na2SO4 +H2O Confirmatory Test   Mg may be detected by the following experiments:-   At first Ammonium Oxalate Test is performed. Experiment  Observation  Inference  To about 20 ml of HCl extract of Plant Ash solution a drop of...

Ammonium Oxalate Test  In Plant Biochemistry Ammonium Oxalate Test is used to detect the presence of Ca in the HCl extract of Plant Ash. Experiment  Observation  Inference  To about 20 ml of HCl extract of Plant Ash extract filtrate , a drop of dil. NH4OH is added to make the sample alkaline.   Finally saturated Ammonium Oxalate (NH4)2C2O4 solution is added. A white ppt is forme in the test tube. It indicates that Ca is present in the supplied sample, as the white ppt fromed if of Calcium oxalate(CaC2O4). Reaction: Ca2+(aq) of the sample + NH4C2O4(aq) → CaC2O4 (s) white ppt + 2NH4+      

Barium Chloride Test      Barium Chloride Test is used to determine the presence of Sulphur in HCl extract of Plant Ash.     Principle:            Barium Chloride performs double displacement reactions i.e.ionic reaction. Experiment  Observation  Inference  To about 5-10 ml of HCl extract of  Plant Ash , a few drops of 5% BaCl2 is added. A white crystalline ppt. is formed. Presence of Sulphur is indicated in the Ash extract.  Reactions:- X2 SO4 (aq)+  BaCl2(aq) →BaSO4(white ppt) + 2 XCl(aq)

Barfoed's Test            Barfoed's Test is used to detect the presence of monosaccharides in an unknown sample solution. Principle: In this reaction copper (ll) acetate reduces to copper(I) oxide (brick red ppt.). Only reducing  sugar responses in this test, not by the non -reducing sugar. Experiment  Observation  Inference  To about 1 ml of sample solution, 2 ml Barfoed's reagent was added and the mixture was boiled in a water bath  for 1- 2 minutes. Brick red ppt or crimson red ppt appeared within 2 minutes of boiling. Reducing sugar present in the sample.Since brick red ppt of copper(ll) oxide appeared within 2  minutes of heating the sample contains glucose/ fructose/galactose ( monosaccharides). If there is no response within 3 minutes of boiling , then it the boiling continued upto 10 minutes. Brick red ppt of copper (ll) oxide settled at the bottom of the test tube very slowly. The sample contai...

Seliwanoff'sTest Purpose:           Seliwanoff'sTest is performed to distinguish between ketose sugar and aldose sugar.  Composition of the Reagent:          0.1 gm resorcinol in 100 ml of 0.5 N HCl i.e., 50%(v/v) HCl.   Principles: (i) In Conc. HCl , ketoses dehydrated and produce hydroxymethylfurfural rapidly. (ii) This furfural derivative reacts with the resorcinol and produced deep-red /cherry red ketooses (of fructose). Experiment  Observation  Inference  1 ml sample solution + 3 ml Seliwanoff's reagent. The mixture is heated over the flame for 30 seconds. The mixture solution turns cherry red rapidly. Ketoses (of fructose) present in the sample solution.   Note:  Hydrolysed sucrose also responses in this test as fructose is one of the product of the hydrolysed sucrose. Reactions:- D-glucose of the sample + HCl (H+) --->Hydroxymethylfurfural + 3 ...

Benedict's Test It is a Reduction Test in Alkaline Medium to know the nature of an unknown Carbohydrate.     Benedict's reagent contains dissolved Sodium citrate , Sodium carbonate and  Copper sulphate.     Preparation: Add 86.5 gm sodium citrate and  50 gm sodium carbonate in 350 ml distilled water to make solution 'A'. Add 8.6 gm copper sulphate in 50 ml distilled water to make solution 'B'. Mix 'A' and 'B' together and add 100 ml distilled water to make 500 ml Benedict's qualitative reagent. Experiment  Observation  Inference To a dry-clean test tube 3ml sample solution is taken, then 2-3 ml of Benedict's qualitative reagent is added and finally boiled for 5 minutes. Green,Yellow or Brick-red ppt.,is formed depending upon the amount of reducing sugar present in the sample. Presence of Reducing sugar in the supplied sample soln. Green ppt. indicates about 0.5 g% concentration. Yellow ppt. indicates about  1 g % concentra...