Enzymes

Question 1

When a reaction is performed in zero-order kinetics
a. The rate of the reaction is independent of the substrate concentration
b. The substrate concentration is very low
c. The rate of reaction is directly proportional to the substrate
concentration
d. The enzyme level is always high

Answer 1

a. The rate of the reaction is independent of the substrate concentration

Question 2

Activation energy is
a. Decreased by enzymes
b. The energy needed for an enzyme reaction to stop
c. Increased by enzymes
d. Very high in catalyzed reactions

Answer 2

a. Decreased by enzymes

Question 3

Enzyme reaction rates are increased by increasing temperatures until they
reach the point of denaturation at
a. 40–60°C
b. 25–35°C
c. 100°C
d. 37°C

Answer 3

a. 40–60°C

Question 4

An example of using enzymes as reagents in the clinical laboratory is
a. The hexokinase glucose method
b. The diacetyl monoxime blood urea nitrogen (BUN) method
c. The alkaline picrate creatinine method
d. The biuret total protein method

Answer 4

a. The hexokinase glucose method

Question 5

Activity of enzymes in serum may be determined rather than concentration
because
a. The amount of enzyme is too low to measure
b. The temperature is too high
c. There is not enough substrate
d. The amount of enzyme is too high to measure

Answer 5

a. The amount of enzyme is too low to measure

Question 6

The isoenzymes LD-4 and LD-5 are elevated in
a. Liver disease
b. Pulmonary embolism
c. Renal disease
d. Myocardial infarction

Answer 6

a. Liver disease

Question 7

Which CK isoenzyme is elevated in muscle diseases?
a. CK-MM
b. CK-BB
c. CK-MB
d. CK-NN

Answer 7

a. CK-MM

Question 8

Elevation of serum amylase and lipase is commonly seen in
a. Acute pancreatitis
b. Acute appendicitis
c. Gallbladder disease
d. Acid reflux disease

Answer 8

a. Acute pancreatitis

Question 9

The saccharogenic method for amylase determinations measures
a. The amount of product produced
b. The amount of substrate consumed
c. The amount of iodine present
d. The amount of starch present

Answer 9

a. The amount of product produced

Question 10

Elevation of tissue enzymes in serum may be used to detect
a. Tissue necrosis or damage
b. Inflammation
c. Infectious diseases
d. Diabetes mellitus

Answer 10

a. Tissue necrosis or damage

Question 11

Which of the following enzyme patterns is MOST diagnostic of Duchennetype muscular dystrophy?
a. Total CK level that is 5 to 10 times the ULN
b. Total CK level that is 25 times the ULN
c. Total CK level that is 50 to 100 times the ULN
d. Total CK level that is 1,000 times the ULN

Answer 11

c. Total CK level that is 50 to 100 times the ULN

Question 12

Which of the following preanalytical errors most commonly causes false
increases in serum enzyme measurements?
a. The patient was not fasting prior to blood draw.
b. The blood sample was not maintained on ice upon collection and
during transport to the laboratory.
c. The serum was not separated from red blood cells within 1 hour.
d. The patient smoked three cigarettes just prior to blood collection.
e. The blood sample was not protected from light upon collection and
during transport to the laboratory.

Answer 12

c. The serum was not separated from red blood cells within 1 hour.