Problem 19.91 Apple slices and peeled potatoes rapidly brown in open air due to
ID: 549947 • Letter: P
Question
Problem 19.91 Apple slices and peeled potatoes rapidly brown in open air due to the presence of phenolases. Phenolases cause the oxidation of phenolic molecules like tyrosine to quinones, colored molecules responsible for the brown colors seen. An experiment comparing the time it took for a change to occur in the color of apple slices versus potato slices was done to test for phenolase activity. Then, a second experiment was done with new apple and potato slices with H202 measuring time until bubbles appeared EnzymeApplePotato Phenolase 180 sec. 150 sec Catalase 10 sec. 20 sec. Part A Which sample contains more phenolase? Why? O An apple contains more phenolase because the rate of reaction is faster for apples than it is for potatoes A potato contains more phenolase because the rate of reaction is faster for potatoes than it is for apples. Submit My Answers Give Up Part B Which sample contains more catalase? Why? O A potato contains more catalase because the rate of reaction is faster for potatoes than for apples. O An apple contains more catalase because the rate of reaction is faster for apples than for potatoes. Submit My Answers Give Up Part C What variable(s) in the experiment would affect your answers to parts A and B? O the variety of apple or potato, the size of slices and potato peel thickness O the variety of apple or potato O season of the year, when the experiment was conducted the size of slices and potato peel thickness Submit My Answers Give Up Part D Which enzyme has the higher turnover rate? O Phenolase has a higher turnover number because the time for the reaction to occur is shorter for phenolase than for catalase O Catalase has a higher turnover number because the time for the reaction to occur is shorter for catalase than for phenolase O Catalase and phenolase have an equal turnover number because the time for the reaction to occur depends on the amount of the enzyme, not the turnover rate. Submit My Answers Give UpExplanation / Answer
Part A As we know the rate of a reaction is inversely proportional to the time and enzyme make the rate of reaction faster. From the above sentence, we can understand that the reaction which is taking less time has higher amount of enzyme. So from the above result, we can say that the a potato contain more phonelase compared to an apple because rate of the reaction is faster in case of potato (taking 150 sec.) compared to rate of reaction of an apple (taking 180 sec.). Hence,
Ans: A potato contains more phenolase because the rate of reaction is faster for potatoes than it it is for apples.
Part B Same explanation as in case of Part A. According to that we can say that an apple takes 10 sec. to complete the reaction while a potate takes 20 sec. So, rate of the reaction is faster in case of apple compared to that of a potato. So, here trend is opposite. An apple has more catalase compared to a potato. Hence,
Ans: An apple contains more catalase because the rate of reaction is faster for apples that for potatoes.
Part C As we know that the enzyme activity also depends upon the amount of substrate present in the compound. If we have less amount of phenolic compounds in one compared to second. So, we will get the wrong results of enzyme activity. Here the valid statements which indicate the amount of substrate in the compounds (apple and potato) are the variety of apple or potato and size of silices and potato peel thickness. Hence,
Ans: the variety of apple or potato, the size of silices and potato peel thickness.
Part D As we know different enzymes have different turnover number and turnover number depend on the maximum number of substrate converted to product per unit of time and per unit of concentration of enzyme.
So, as the time taken to maximum conversion of substrate to product for catalalase (10 and 20 sec.) is lower than that of phenolase (180 and 150 sec.). So turnover number for the catalase is higher than that of phenolase. Hence,
Ans: Catalase has a higher turnover number because the time for the reaction to occur is shorter for catalase than for phenolase.