etea medical mcqs

Category: Biology etea medical mcqs

No.	Topics.	No.	Topics.
1.	1ST YEAR BIO RANDOM MCQs KP TEXT BOOK	2.	ACELLULAR LIFR
3.	BIOENERGETICS	4.	BIOLOGICAL MOLECULES
5.	Biotechnology	6.	CELL STRUCTURE & FUNCTION
7.	Circulation	8.	COORDINATION & CONTROL/ NERVOUS & CHEMICAL COORDINATION
9.	DIVERSITY AMONG ANTMALS (THE KTNGDOM ANIMALIA)	10.	ENZYMES
11.	EVOLUTION	12.	Form and Function in Plants
13.	Homeostasis ( Mainly Kidney Portion )	14.	INHERITANCE
15.	lmmunity	16.	PROKARYOTES (KTNGDOM MONERA)
17.	REPRODUCTION	18.	Respiration
19.	Respiratory system	20.	SUPPORT & MOVEMENT

The effect of increasing enzyme concentration on the rate of an enzyme-catalyzed reaction, assuming abundant substrate, is typically:

A decrease in reaction rate
No change in reaction rate
A proportional increase in reaction rate
An initial increase followed by a plateau

The optimal pH range for most human digestive enzymes operating in the small intestine is around 7.0-8.0. Pepsin, an enzyme in the stomach, however, functions optimally at pH 2. This variation highlights enzymes’:

Sensitivity to substrate concentration
Specificity to temperature
Adaptability to environmental conditions
Ir Requirement for cofactors

A non-competitive inhibitor reduces the rate of an enzymatic reaction by:

Binding to the active site directly
Increasing the enzyme's optimal temperature
Altering the shape of the active site indirectly
Competing with the substrate for binding

The observation that increasing the concentration of a substrate beyond a certain point does not further increase the rate of an enzyme-catalyzed reaction suggests:

The enzyme has been denatured.
The activation energy has become too high.
All active sites are saturated with substrate.
Product inhibition has occurred.

An enzyme’s ability to facilitate a specific biochemical reaction relies heavily on the precise fit between its active site and the reactant molecule, a concept fundamental to the:

Allosteric regulation model
Induced fit model
Lock and key model
Feedback inhibition mechanism

The selective nature of enzyme action, where each enzyme typically acts on a single substrate or a small group of related substrates, is best explained by its:

Ability to lower activation energy
Three-dimensional structure
Sensitivity to temperature changes
High molecular weight

During enzymatic catalysis, the formation of a transient, unstable intermediate structure, where the substrate’s bonds are strained, is referred to as the:

Product complex
Substrate complex
Transition state
Active site

A defining characteristic of biological catalysts is their capacity to significantly alter reaction rates without undergoing permanent chemical change, allowing for their continuous participation in cellular processes.

Enzymes become part of the final product.
Enzymes are consumed in the reaction.
Enzymes remain unchanged chemically.
Enzymes increase the activation energy.

The protein nature of enzymes means they are essentially polymers of:

Monosaccharides
Fatty acids
Amino acids
Nucleotides

The enzyme carbonic anhydrase rapidly converts carbon dioxide and water into carbonic acid. This high turnover rate highlights the enzyme’s:

Reusability
Specificity
Catalytic efficiency
Sensitivity to pH

When the temperature of an enzymatic reaction is gradually increased from a very low value, the reaction rate typically:

Decreases linearly
Remains constant
Increases until an optimum, then decreases
Increases indefinitely

In a scenario where a patient has a genetic disorder causing an enzyme to be synthesized with an altered non-active site region, but still affecting its function, this might suggest:

Competitive inhibition
Allosteric regulation impairment
Irreversible active site modification
Substrate deficiency

The crucial difference between reversible and irreversible enzyme inhibition is that irreversible inhibitors typically:

Compete with the substrate at the active site.
Form strong, often covalent, bonds with the enzyme.
Are easily removed by increasing substrate concentration.
Only reduce enzyme activity temporarily.

Why is it crucial for an enzyme’s active site to have a precise three-dimensional shape?

To ensure it can bind to any molecule.
To allow for non-specific catalysis.
To facilitate specific substrate binding and effective catalysis.
To prevent denaturation at high temperatures.

The rate of an enzyme-catalyzed reaction decreases if the enzyme concentration is kept constant but the substrate concentration is severely reduced. This is because:

Enzyme molecules start to denature.
Product inhibition becomes dominant.
There are fewer enzyme-substrate collisions.
The activation energy increases.

The formation of the enzyme-substrate complex is temporary, allowing the enzyme to be released unchanged after product formation, illustrating its:

Specificity
Sensitivity
Reusability
Saturation

The specific region on an enzyme molecule where catalysis takes place is the:

Allosteric site
Regulatory site
Binding site
Active site

An enzyme’s catalytic activity is attributed to its unique spatial arrangement, which allows it to:

React with all available substrates.
Form a stable complex with the product.
Provide a microenvironment conducive to bond rearrangement.
Increase the kinetic energy of reactants.

If an enzyme’s optimal temperature is 37?C, then incubating it at 25?C would likely result in:

Denaturation
No activity
Reduced activity
Optimal activity

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