BIOCHEM C785 TEST PAPER 2026
COMPLETE QUESTIONS AND CORRECT
ANSWERS
◍ Salivary amylase, an enzyme responsible for partial digestion of
carbohydrates, has optimum activity at a pH value of 6.8.
What is the impact on the activity if the pH is decreased to 4.0?
Significantly increase
Significantly decrease
Slightly decrease
Slightly increase. Answer: Significantly decrease
A drop in pH from 6.8 to 4.0 is a significant change in pH. Recall that
the hydrogen bonds and ionic bonds that hold protein structures
together can be broken by changes in pH. The disruption in protein
structure due to this pH change will also significantly decrease
amylase activity.
◍ Low levels of glutathione are associated with certain types of
ovarian and breast cancers. In the synthesis of glutathione, glutathione
accumulates in the cell, binding to an enzyme in the pathway and
,temporarily preventing the synthesis of glutathione. Which type of
inhibition is described by this scenario?
Feedback
Competitive
Allosteric
Uncompetitive. Answer: Feedback
The keywords here are that glutathione accumulates and binds to an
enzyme in the pathway to prevent synthesis. Feedback inhibition
occurs when a product of a pathway turns into an inhibitor of an
enzyme earlier in the pathway.
◍ Lipase is an enzyme with an optimum temperature of 98.6°F and
an optimum pH of 7.0 in the duodenum in the human body. If a
person is experiencing a fever of 99.8°F, what will increase the
activity of the lipase enzyme?
Decrease in temperature
Increase in temperature
Decrease of the substrate of the enzyme
,Increase of pH of duodenum to 8.0. Answer: Decrease in temperature
An enzyme will have the highest activity when it is under optimal
conditions. In this case, the fever of 99.8 is above the optimal
temperature, so lowering the temperature will increase activity.
◍ The enzyme glucokinase only binds its substrate glucose and
converts glucose into the product glucose-6-phosphate. Which
property of enzymes is described by this scenario?
Specificity
Activation energy
Induced fit
Reaction rate. Answer: Specificity
Enzymes have a high degree of specificity. They will bind to one
specific class of molecules and usually catalyze only one type of
reaction.
◍ Low levels of glutathione are associated with neurological,
immunological, and cardiovascular impairments. Two enzymatic
reactions are involved in the synthesis of glutathione. In the second
, enzymatic reaction, glutathione synthetase converts glycine to
glutathione. What would potentially decrease risks associated with
low levels of glutathione?
Increasing the amount of glycine in the diet
Noncompetitive inhibitor of glutathione synthetase
Uncompetitive inhibitor of glutathione synthetase
Decreasing the amount of glycine in the diet. Answer: Increasing the
amount of glycine in the diet
One way to increase glutathione levels is to increase the activity of
glutathione synthetase. Glutathione synthetase activity can be
increased by increasing the amount of substrate, or glycine available.
◍ Which class of enzymes impacts protein function by temporarily
removing a phosphate?
Kinase
Phosphatase
Polypeptide
COMPLETE QUESTIONS AND CORRECT
ANSWERS
◍ Salivary amylase, an enzyme responsible for partial digestion of
carbohydrates, has optimum activity at a pH value of 6.8.
What is the impact on the activity if the pH is decreased to 4.0?
Significantly increase
Significantly decrease
Slightly decrease
Slightly increase. Answer: Significantly decrease
A drop in pH from 6.8 to 4.0 is a significant change in pH. Recall that
the hydrogen bonds and ionic bonds that hold protein structures
together can be broken by changes in pH. The disruption in protein
structure due to this pH change will also significantly decrease
amylase activity.
◍ Low levels of glutathione are associated with certain types of
ovarian and breast cancers. In the synthesis of glutathione, glutathione
accumulates in the cell, binding to an enzyme in the pathway and
,temporarily preventing the synthesis of glutathione. Which type of
inhibition is described by this scenario?
Feedback
Competitive
Allosteric
Uncompetitive. Answer: Feedback
The keywords here are that glutathione accumulates and binds to an
enzyme in the pathway to prevent synthesis. Feedback inhibition
occurs when a product of a pathway turns into an inhibitor of an
enzyme earlier in the pathway.
◍ Lipase is an enzyme with an optimum temperature of 98.6°F and
an optimum pH of 7.0 in the duodenum in the human body. If a
person is experiencing a fever of 99.8°F, what will increase the
activity of the lipase enzyme?
Decrease in temperature
Increase in temperature
Decrease of the substrate of the enzyme
,Increase of pH of duodenum to 8.0. Answer: Decrease in temperature
An enzyme will have the highest activity when it is under optimal
conditions. In this case, the fever of 99.8 is above the optimal
temperature, so lowering the temperature will increase activity.
◍ The enzyme glucokinase only binds its substrate glucose and
converts glucose into the product glucose-6-phosphate. Which
property of enzymes is described by this scenario?
Specificity
Activation energy
Induced fit
Reaction rate. Answer: Specificity
Enzymes have a high degree of specificity. They will bind to one
specific class of molecules and usually catalyze only one type of
reaction.
◍ Low levels of glutathione are associated with neurological,
immunological, and cardiovascular impairments. Two enzymatic
reactions are involved in the synthesis of glutathione. In the second
, enzymatic reaction, glutathione synthetase converts glycine to
glutathione. What would potentially decrease risks associated with
low levels of glutathione?
Increasing the amount of glycine in the diet
Noncompetitive inhibitor of glutathione synthetase
Uncompetitive inhibitor of glutathione synthetase
Decreasing the amount of glycine in the diet. Answer: Increasing the
amount of glycine in the diet
One way to increase glutathione levels is to increase the activity of
glutathione synthetase. Glutathione synthetase activity can be
increased by increasing the amount of substrate, or glycine available.
◍ Which class of enzymes impacts protein function by temporarily
removing a phosphate?
Kinase
Phosphatase
Polypeptide
