What is the sum of all biochemical reactions that occur in a living organism called?

• Metabolism

• Anabolism

• Catabolism

• Glycolysis

Answer explanation

The sum of all biochemical reactions in a living organism is called metabolism. It encompasses both anabolism (building up) and catabolism (breaking down) processes, making it the correct choice.

Which process is characterized as an energy-requiring process where small molecules are joined to form larger molecules?

• Hydrolysis

• Anabolism

• Isomerization

• Catabolism

Answer explanation

Anabolism is the process that requires energy to synthesize larger molecules from smaller ones, contrasting with catabolism, which breaks down molecules. Therefore, the correct answer is anabolism.

What is the primary energy currency of the cell?

• ATP

• ADP

• FADH2

• NADH

Answer explanation

ATP (adenosine triphosphate) is the primary energy currency of the cell, providing energy for various cellular processes. ADP, FADH2, and NADH are involved in energy transfer but do not serve as the main energy currency.

What type of reaction involves the transfer of a chemical functional group from one molecule to another?

• Group-Transfer

• Hydrolysis

• Isomerization

• Oxidation-Reduction

Answer explanation

The correct answer is 'Group-Transfer' because this type of reaction specifically involves the transfer of a chemical functional group from one molecule to another, distinguishing it from other reaction types.

What is the Gibbs free energy change (ΔG) if the products are more stable than the reactants?

• ΔG = 1

• ΔG > 0

• ΔG = 0

• ΔG < 0

Answer explanation

When the products are more stable than the reactants, the reaction is spontaneous, leading to a negative Gibbs free energy change (ΔG < 0). This indicates that the process can occur without external energy input.

Which of the following is a coenzyme used in redox reactions?

• ADP

• NAD+

• Coenzyme A (CoA)

• ATP

Answer explanation

NAD+ is a coenzyme that plays a crucial role in redox reactions by accepting electrons and becoming reduced to NADH. This process is essential for cellular respiration and energy production, unlike ADP, CoA, and ATP.

What type of reaction uses water to split a single molecule into two separate molecules?

• Nonhydrolytic cleavage

• Group-Transfer

• Isomerization

• Hydrolysis

Answer explanation

Hydrolysis is the reaction that uses water to break down a molecule into two separate molecules. This process involves the addition of water, which cleaves the bonds in the original molecule.

Which metabolic pathway is both anabolic and catabolic?

• Glycolysis

• Krebs cycle

• Citric acid cycle

• Oxidative phosphorylation

Answer explanation

The Krebs cycle, also known as the citric acid cycle, is both anabolic and catabolic. It breaks down acetyl-CoA to produce energy while also providing intermediates for biosynthesis, making it a key metabolic hub.

What is the standard free energy change (ΔG^o') used for?

• To predict the spontaneity of biochemical reactions

• To determine enzyme activity

• To assess temperature changes

• To calculate pH levels

Answer explanation

The standard free energy change (ΔG°') indicates whether a biochemical reaction is spontaneous. A negative ΔG°' suggests the reaction can occur without external energy, making it crucial for predicting reaction spontaneity.

Which of the following is NOT a category of biochemical reactions?

• Fermentation

• Non-hydrolytic cleavage

• Oxidation-Reduction

• Bond formation

Answer explanation

Fermentation is a specific type of biochemical reaction, while non-hydrolytic cleavage, oxidation-reduction, and bond formation are broader categories. Therefore, fermentation is NOT a general category of biochemical reactions.