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BIO NMDCAT

1785 questions found

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📁 ACELLULAR LIFR 20 📁 AIDS and HIV Infection 50 📁 and nerve impulse Reflexes and reflex arc 0 📁 Arthritis 0 📁 axon 0 📁 BIOENERGETICS 0 📁 Biological Importance of Water 95 📁 BIOLOGICAL MOLECULES 126 📁 Biotechnology 0 📁 Biotechnology and Health Care 0 📁 Blood Vessels 0 📁 Brain 25 📁 Carbohydrates 100 📁 Cardiac cycle and phases of Heartbeat 0 📁 cell body 0 📁 cell membrane 70 📁 CELL STRUCTURE & FUNCTION 100 📁 Chromosomes 76 📁 Circulation 0 📁 Concept of Evolution 50 📁 Conjugated molecules 100 📁 COORDINATION & CONTROL NERVOUS & CHEMICAL COORDINATION 0 📁 Cytoplasmic Organelles 75 📁 Darwinism 50 📁 dendrites 0 📁 DIVERSITY AMONG ANTMALS (THE KTNGDOM ANIMALIA) 0 📁 ENZYMES 108 📁 EVOLUTION 0 📁 Factors that Affect the Rate of Enzyme Reactions 60 📁 Form and Function in Plants 0 📁 Gene linkage and crossing over 0 📁 Homeostasis (kidney specifically) 0 📁 Homeostasis Mainly Kidney Portion nmdcat etea 0 📁 Human Heart 0 📁 Human Reproductive system 0 📁 Human Reproductive system-Menstrual cycle 0 📁 Human skeleton 0 📁 INHERITANCE 0 📁 Inhibitors 40 📁 Joints 0 📁 Lamarckism 50 📁 Lipids 45 📁 lmmunity 0 📁 Lymphatic system 0 📁 Mendel's laws of Inheritance 0 📁 Menstrual cycle 0 📁 Mode of Enzyme Action 60 📁 Muscle contraction 0 📁 Muscles 0 📁 myelin sheath 0 📁 Neurons 41 📁 PROKARYOTES (KTNGDOM MONERA) 0 📁 Prokaryotic and Eukaryotic cell 0 📁 Proteins 95 📁 Receptors 40 📁 REPRODUCTION 0 📁 Respiration 15 📁 Respiratory system 0 📁 Ribonucleic acid (RNA) 100 📁 Sexually transmitted diseases 50 📁 Skeletal muscles 0 📁 Specific Defense Mechanism 0 📁 Structure of DNA 98 📁 SUPPORT & MOVEMENT 0 📁 Viruses 46 📁 X-linked Recessive inheritance 0

Practice Questions

A decrease in enzyme concentration while keeping substrate concentration constant causes

A. An increase in Vmax
B. A decrease in the number of available active sites
C. Increased substrate affinity
D. Greater thermal stability of the enzyme

Fewer enzyme molecules mean fewer active sites are available for catalysis, reducing the reaction rate.

nmdcat.online BIO NMDCAT
Jul 11, 2026

During enzyme-catalyzed reactions, extremely alkaline conditions generally lead to

A. Improved substrate binding
B. Disruption of ionic and hydrogen bonds within the enzyme
C. Increased enzyme synthesis
D. Increased activation energy of the substrate

Highly alkaline conditions alter the tertiary structure by disrupting weak bonds, leading to reduced catalytic activity or denaturation.

nmdcat.online BIO NMDCAT
Jul 11, 2026

Most human intracellular enzymes function best near neutral pH because this reflects the physiological environment of body cells.

nmdcat.online BIO NMDCAT
Jul 11, 2026

During an experiment, increasing temperature from 35°C to 40°C causes a higher reaction rate. The most appropriate explanation is

A. More enzyme molecules are synthesized immediately
B. Increased molecular collisions between enzyme and substrate
C. Substrate molecules become permanently activated
D. The enzyme changes its amino acid sequence

Higher temperature increases kinetic energy, producing more frequent effective collisions until the optimum temperature is reached.

nmdcat.online BIO NMDCAT
Jul 11, 2026

A decrease in reaction rate at temperatures above the optimum is primarily associated with

A. Reduced substrate concentration
B. Loss of the enzyme's tertiary structure
C. Increased enzyme concentration
D. Formation of additional active sites

Excessive heat disrupts the three-dimensional conformation required for catalytic activity, resulting in denaturation.

nmdcat.online BIO NMDCAT
Jul 11, 2026

A temperature increase beyond the optimum value causes enzyme activity to decline primarily because

A. Substrate molecules become inactive
B. The active site loses its specific three-dimensional shape
C. More enzyme-substrate complexes are formed
D. The activation energy becomes zero

High temperature disrupts hydrogen bonds and other weak interactions responsible for maintaining enzyme structure, causing denaturation and loss of catalytic function.

nmdcat.online BIO NMDCAT
Jul 11, 2026

During enzyme-catalyzed reactions, extremely low temperatures generally produce

A. Complete destruction of the enzyme
B. Reduced reaction rate without permanent damage to the enzyme
C. Permanent inactivation of the active site
D. Increased catalytic efficiency

Low temperature decreases molecular motion and collision frequency. The enzyme usually regains normal activity when returned to its optimum temperature.

nmdcat.online BIO NMDCAT
Jul 11, 2026

An increase in substrate concentration while enzyme concentration remains constant initially results in

A. A proportional increase in reaction rate until saturation occurs
B. Immediate denaturation of the enzyme
C. Continuous decrease in reaction rate
D. Complete inhibition of enzyme activity

Initially, more substrate molecules increase enzyme-substrate complex formation. Once all active sites become occupied, the reaction reaches maximum velocity (Vmax).

nmdcat.online BIO NMDCAT
Jul 11, 2026

Regarding enzyme concentration, doubling the enzyme concentration while substrate remains abundant results in

A. Approximately doubling the reaction rate
B. No measurable change in reaction rate
C. A decrease in substrate affinity
D. Permanent denaturation of enzymes

With excess substrate available, more enzyme molecules provide additional active sites, increasing the overall reaction rate nearly proportionally.

nmdcat.online BIO NMDCAT
Jul 11, 2026

The characteristic feature of optimum pH is

A. Complete denaturation of all proteins
B. Maximum catalytic activity of the enzyme
C. Highest substrate concentration
D. Lowest enzyme concentration

Each enzyme functions best within a specific pH range because proper ionization of amino acid residues in the active site is maintained.

nmdcat.online BIO NMDCAT
Jul 11, 2026

A decrease in pH far below the optimum value causes reduced enzyme activity because

A. The substrate completely disappears
B. Ionic and hydrogen bonds maintaining enzyme structure become disrupted
C. The activation energy becomes negative
D. Product concentration becomes zero

Extreme pH alters the ionization of amino acid side chains and disrupts the interactions maintaining the enzyme's tertiary structure.

nmdcat.online BIO NMDCAT
Jul 11, 2026

In enzyme kinetics, the reaction reaches a maximum rate when

A. Every enzyme molecule has an occupied active site
B. Product concentration becomes zero
C. Temperature reaches freezing point
D. The enzyme becomes denatured

At substrate saturation, all available active sites are occupied, so adding more substrate cannot further increase the reaction rate.

nmdcat.online BIO NMDCAT
Jul 11, 2026

During laboratory investigation of enzyme activity, maintaining constant temperature is essential because

A. Temperature directly influences molecular collisions and enzyme structure
B. Temperature changes substrate identity
C. Temperature changes enzyme concentration
D. Temperature eliminates activation energy

Temperature affects both reaction kinetics and enzyme stability. Even small deviations from the optimum can alter experimental results.

nmdcat.online BIO NMDCAT
Jul 11, 2026

In living organisms, an increase in temperature from 20°C to the optimum value generally results in

A. A gradual decrease in enzyme activity
B. An increase in enzyme activity due to greater kinetic energy
C. No change in enzyme activity
D. Permanent denaturation of the enzyme

As temperature rises toward the optimum, enzyme and substrate molecules move faster, increasing successful collisions and enzyme-substrate complex formation. Denaturation usually occurs only above the optimum temperature.

nmdcat.online BIO NMDCAT
Jul 11, 2026

Regarding enzyme activity, the optimum temperature represents the condition at which

A. Enzyme molecules are permanently stable
B. The rate of enzyme-catalyzed reaction reaches its maximum
C. The enzyme becomes resistant to pH changes
D. The substrate concentration becomes limiting

Every enzyme has an optimum temperature where catalytic activity is highest. Above this temperature, the enzyme's three-dimensional structure begins to lose stability.

nmdcat.online BIO NMDCAT
Jul 11, 2026

Donation of a proton from hydronium ion (H?O?) in solution to the substrate is an example of

A. General acid catalysis
B. Specific acid catalysis
C. Covalent catalysis
D. Metal ion catalysis
nmdcat.online BIO NMDCAT
Jul 11, 2026

The hydrophobic effect contributes to enzyme catalysis primarily by

A. Dissolving the enzyme in membranes
B. Driving substrate binding into the hydrophobic active site
C. Preventing substrate entry
D. Causing enzyme denaturation
nmdcat.online BIO NMDCAT
Jul 11, 2026

An enediolate intermediate is most likely stabilized by

A. A hydrophobic pocket
B. A positively charged metal ion or lysine residue
C. A negatively charged aspartate residue
D. A neutral cysteine residue
nmdcat.online BIO NMDCAT
Jul 11, 2026
nmdcat.online BIO NMDCAT
Jul 11, 2026
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