BIOLOGY - 4.2 food tests and graphs
IODINE
BIURET TEST
BENEDICT'S TEST
ETHANOL
INITIALLY YELLOW
BLUE / BLACK --> STARCH
2/3 DROPS
EXTRACT IN SOLUTION
DCPIP
5/6 DROPS
INITIALLY BLUE
PURPLE / VIOLET / LILAC --> PROTEIN
WATER BATH THE EXTRACT
ADD SAME QUANTITY AS THE EXTRACT
REDUCING SUGARS --> GREEN < YELLOW < ORANGE < BRICK RED PRECIPITATE
ADD DROPS OF EXTRACT WHILE SHAKING
(VIOLET - ACIDITY) COLORLESS --> VITAMIC C
CHOPPED EXTRACT IN ETHANOL (2 cm^3) AND SHAKE
ADD DISTILLED WATER (2 cm^3) AND SHAKE
WHITE CLOUDY EMULSION --> FATS
40 POINTS PAPER 2 + 15 POINTS FROM PAPER 4 EXTENDED THEORY + 25 POINTS FROM PAPER 6
SEMI-QUANTITATIVE TEST --> NOT A NUMBER BUT HOW MANY
POSITIVE TEST --> STARCH POWDER
TESTS
POSITIVE
NEGATIVE
TO SEE IF THE REAGENT WORKS PROPERLY
TO COMPARE THE RESULTS
REDUCING SUGARS
NO SUCROSE
MONOSACCARIDES
GALACTOSE
FRUCTOSE
GLUCOSE
DISACCARIDES
MALTOSE
LACTOSE
THERMOSTATICALLY CONTROLLED WATER BATH
SEMI - QUANTITIVE TEST
COUNT DROPS TILL THE END
HIGHER CONCENTRATION --> FEWER DROPS
OPPOSITE EXPERIMENT
DCPIP ADDED TO THE EXTRACT
FEWER DROPS --> FEWER VITAMIC C
FINAL RESULT --> DCPIP REMAINS BLUE
THERE IS NO MORE VITAMIC C TO REACT
ERRORS
CROSS CONTAMINATION
3 TIMES
DROPS --> SYRING PREFERABLE ON PIPETTE
COLUR
CHANGE SUBJECTIVE
COMPARE THEM WITH NEGATIVE AND POSITVE TEST (STANDARD CONTROL)
AGAINST A WHITE BACKGROUND
DECOLOURISE THE EXTRACT
SPECTROPHOTOMETER OR COLORIMETER
GRAPHS
DESCRIBE THE GENERAL TREND
GIVE STATISTICS FOR EVIDENCE
INTIAL - FINAL VALUES
EXPLAIN
USE A TABLE
GIVE MORE STATISTICS IF YOU CAN