University of Texas, San Antonio BIOLOGY 1404 Lab 1- Macromolecules Post-Lab Assignment

Results of Carbohydrate Tests


Table 1. Reactions for Reducing Sugars and Starch

Benedict’s Reaction
Tube Solution
Final color and conclusions

1 1ml onion juice Cloudy Yellow


2 1ml potato juice Cloudy Blue


3 1ml 1% sucrose solution Clear Blue


4 1ml 1% glucose solution Cloudy Brown


5 1ml distilled water Clear Blue


1ml 1% reducing sugar (fructose)
6 Cloudy Red
solution


7 1ml 1% starch solution Cloudy Green


8 1ml of your unknown solution Dark Blue



Which one of the solutions is the positive control, and which one of the solutions is the negative
Question 1 reaction?
The solution that had postive control was fructose, and the solution that had a negative cont
Benedict's reaction.




Question 2 Which contains more reducing sugars, potato juice or onion juice? How do you know?
The juice that contained more reducing sugars was the onion juice because the reaction was

, Which one of the solutions is the positive control, and which one of the solutions is the negative
Question 3 reaction?
The solution that had postive control was starch, and the solution that had a negative contro
Iodine reaction.




Question 4 Which colors more intensely for the Iodine Reaction, onion juice or potato juice? Why?
Potato juice colored was more intense for the Iodine Reaction because it had a greater color

,gars and Starch

Iodine Reaction
Final Color and Conclusions

Yellowish Brown ( - , 0.01 )


Bluish Black ( + , 0.1 )


Yellow ( -, 0.0% )


Yellow ( -, 0.0% )


Yellow ( -, 0.0% )


Yellow ( -, 0.0% )


Bluish Black ( + , 0.1 )


Yellow ( -, 0.0% )



utions is the negative control for the Benedict's

had a negative control was distilled water for the




you know?
use the reaction was a yellowish color.