Multiple forms of the same enzymes are also referred to as
Απάντηση
(B)
Isoenzymes
2
In a scenario of non-competitive enzyme behavior
Απάντηση
(C)
Apparent km decreases
3
How does an allosteric enzyme influence enzymatic activity?
Απάντηση
(C)
By changing the enzyme's conformation through binding at a site other than the catalytic site
4
Which regulatory process involves a reversible change to an enzyme through a covalent modification?
Απάντηση
(A)
Phosphorylation of serine OH on the enzyme
5
What characterizes a competitive enzyme inhibitor?
Απάντηση
(D)
It prevents the substrate from binding to the enzyme
6
When [s] equals K, which of the following statements is correct?
Απάντηση
(A)
Half of the enzyme molecules are bound to substrate
7
Which statement is incorrect concerning an enzyme demonstrating allosteric kinetics with cooperative interaction?
Απάντηση
(D)
Removing an allosteric inhibitor might result in a hyperbolic V vs. [s] plot
8
Pantothenic acid plays a crucial role in the function of
Απάντηση
(B)
NADPH
9
Which of the following is not a vitamin deficiency associated with fatty liver?
Απάντηση
(C)
Retinoic acid
10
In which type of enzyme is an inducer not required?
Απάντηση
(D)
Constitutive enzyme
11
Which type of enzyme facilitates the addition of water to a carbon-carbon double bond without breaking the bond?
Απάντηση
(B)
Hydratase
12
The 'Lock and Key' model of enzyme action, proposed by Fisher, suggests that
Απάντηση
(C)
The active site shape matches the substrate
13
In enzyme action competitive inhibition, what is the impact?
Απάντηση
(B)
The apparent Km is increased
14
What is the correct kinetic effect during competitive inhibition?
Απάντηση
(D)
Increases Km without affecting Vmax
15
How do enzymes accelerate reaction rates?
Απάντηση
(B)
Decreasing the energy of activation
16
What is the most helpful test for diagnosing acute hemorrhagic pancreatitis in the initial days?
Απάντηση
(D)
Serum amylase
17
Which test is best for diagnosing acute pancreatitis if mumps is also present?
Απάντηση
(D)
Serum lipase
18
Which condition often shows an increase in the slow-moving fraction of LDH in the pancreas?
Απάντηση
(D)
Acute viral hepatitis
19
Which enzyme is often elevated in individuals with alcoholism?
Απάντηση
(C)
Serum γ-GT
20
Compared to those with purely obstructive jaundice, individuals with hepatocellular jaundice are likely to have
Απάντηση
(B)
Lower serum ALP, Higher LDH and AST activity
21
If results from serum bilirubin, serum ALP, LDH, and AST tests indicate potential obstructive jaundice, what is the most effective test to confirm the diagnosis?
Απάντηση
(B)
Serum 5' nucleotidase
22
Which enzyme test is most useful for distinguishing between elevated serum ALP levels caused by obstructive jaundice versus bone disorders?
Απάντηση
(D)
Serum γ-GT
23
What CK isoenzyme is primarily found in cardiac muscle?
Απάντηση
(D)
MM and MB only
24
What LDH isoenzyme fraction typically shows a proportionate increase in liver and skeletal muscle disorders?
Απάντηση
(C)
LDH-3 and LDH-4
25
Following an acute myocardial infarction, what enzyme test provides the best predictive value on the third day?
Απάντηση
(D)
Serum LDH
26
Which of the following conditions is NOT typically associated with elevated serum AST activity?
Απάντηση
(D)
Peptic ulcer
27
When is the estimation of serum AST most significant following an acute myocardial infarction?
Απάντηση
(B)
Second day
28
In which of the following organ diseases would LDH-1 and LDH-2 isoenzymes be released into the plasma?
Απάντηση
(B)
Heart, Kidney and R.B.C
29
What is true about non-functional enzymes in plasma?
Απάντηση
(D)
All of these
30
Which of the following is NOT a component of pyruvate dehydrogenase?
Απάντηση
(A)
Biotin
31
Elevated levels of LDH-5 are typically observed in all of the following conditions EXCEPT:
Απάντηση
(D)
Pulmonary embolism
32
What substance is broken down by the enzyme diastase?
Απάντηση
(B)
Starch
33
Which of the following statements accurately describes enzymes?
Απάντηση
(B)
Enzymes are highly specific in their action
34
What factors influence the activity of an enzyme?
Απάντηση
(E)
All of these
35
Which statement about enzymes is INCORRECT?
Απάντηση
(C)
They are destroyed after the completion of the reaction they catalyse
36
Approximately how many distinct enzymes have been identified?
Απάντηση
(C)
50
37
What type of compound is nicotine, found in tobacco?
Απάντηση
(A)
Alkaloid
38
The toxic alkaloid found in hemlock oil is:
Απάντηση
(A)
Cocaine
39
What solvent is commonly used to extract alkaloids during purification?
Απάντηση
(B)
Dil HCl
40
Which reagent is most useful for estimating the number of N-MC groups in alkaloids?
Απάντηση
(A)
HI
41
In the context of enzyme kinetics, a competitive inhibitor
Απάντηση
(A)
Raises the Km value while leaving the Vmax unchanged
42
Regarding the Michaelis constant (Km), which statement is accurate?
Απάντηση
(D)
It represents the substrate concentration at which the reaction velocity is half of its maximum
43
When assessing an enzyme-catalyzed reaction with substrate concentrations significantly below Km, what best describes the relationship between reaction velocity and substrate concentration?
Απάντηση
(D)
Directly proportional to the substrate concentration
44
What is the impact of a non-competitive inhibitor?
Απάντηση
(B)
It causes a reduction in the observed Vmax
45
Which characteristic is NOT generally associated with allosteric enzymes?
Απάντηση
(C)
They adhere to Michaelis-Menten kinetics
46
An atypical isoenzyme does NOT necessarily
Απάντηση
(A)
Function as an oxidoreductase
47
LDH assays are most valuable in diagnosing conditions affecting the
Απάντηση
(A)
Cardiac muscle
48
What type of chemical interactions are primarily responsible for the binding of coenzymes and substrates to enzymes like LDH?
Απάντηση
(D)
Covalent bonds
49
How many distinct protein forms can be found in normal LDH?
