Enzyme (temp)

In an experiment to investigate the effect of temperature on the activity of a digestive enzyme X, the time taken for the digestion of a fixed amount of substrate by this enzyme was recorded. Which of the following graphs shows the most likely results of the experiment?

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• B

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• D

Tags

NGSS.HS-PS1-5

The graph below shows the effect of temperature on enzyme activity:

Which of the following statements correctly describes the enzyme reaction?

• The enzyme is denatured at 0^oC and 60^oC.

• The reaction taking place at 50^oC is faster than that at 20^oC.

• There are more collisions between substrate and enzyme molecules at 40^oC than 60^oC.

• The amount of product collected at the end of the reaction is greatest if the reaction takes place at 40^oC.

Two boiling tubes containing 5 cm³ of hydrogen peroxide solution and 1 cm³ of catalase solution respectively were kept at 25^oC for 10 minutes. The contents of the two tubes were then mixed and maintained at the same temperature, and the amount of oxygen released was recorded for 5 minutes. The results are shown in the graph below:

The line levels off at the 3^rd minutes. Which of the following is a correct explanation for this?

• The reaction stops at the 3^rd minutes because catalase has been used up.

• The reaction stops at the 3^rd minutes because hydrogen peroxide has been used up.

• The reaction rate reaches the maximum at the 3^rd minutes because the amount of oxygen released is highest.

• The reaction rate reaches the maximum at the 3^rd minutes because there is no more increase in the amount of oxygen released.

The same experiment was repeated but the contents were kept at 35^oC. Which of the following would best indicate the results of this experiment?

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Which of the following graphs correctly shows the changes in the amount of products in a reaction catalysed by a human enzyme at different temperatures?

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Two test tubes containing 5 cm³ of hydrogen peroxide solution and 1 cm³ of catalase solution respectively were kept at 30°C for 30 minutes. The content of the two tubes were then mixed and maintained at the same temperature, and the amount of oxygen released was recorded for 5 minutes. The same experiment was repeated at 40°C. The results are shown in the graph below:

The initial rate of oxygen production at 40°C is higher than that at 30°C because

• catalase is denatured at the lower temperature.

• oxygen is less soluble at the higher temperature.

• more active sites are present in the enzyme molecules at the higher temperature.

• the substrate molecules have more kinetic energy at the higher temperature.

A third experiment was carried out as before but the contents were kept at 90°C. Which of the following would best indicate the result of this experiment?

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