AP Bio Unit 6 Practice Quiz

Mitochondria generate most of the cell's ATP through cellular respiration. Their role in energy production is critical for cellular function.

Glycolysis is the initial step of cellular respiration where glucose is broken down into pyruvate. This process occurs in the cytoplasm and produces a small amount of ATP.

Enzymes act as catalysts that reduce the activation energy required for biochemical reactions. This speeds up the reaction rates allowing vital processes to occur under physiological conditions.

Oxygen acts as the final electron acceptor in the electron transport chain during aerobic respiration. This role is critical in the process that ultimately produces water and drives ATP synthesis.

During glycolysis, although 4 ATP molecules are produced, 2 ATP molecules are consumed in the early steps of the process. This results in a net gain of 2 ATP per glucose molecule.

The electron transport chain is located in the inner mitochondrial membrane. This location is essential for establishing the proton gradient used in the synthesis of ATP.

Oxidative phosphorylation is responsible for generating the majority of ATP during cellular respiration. The process utilizes the proton gradient created by the electron transport chain to drive ATP synthesis.

Acetyl-CoA is the key molecule that enters the citric acid cycle for the complete oxidation of carbon compounds. It is produced from pyruvate following glycolysis.

Uncoupling proteins allow protons to re-enter the mitochondrial matrix without passing through ATP synthase. This process reduces the proton gradient, leading to a decrease in ATP production as energy is released as heat instead.

Fermentation regenerates NAD+ from NADH under anaerobic conditions, allowing glycolysis to continue. This pathway is essential when oxygen is not available for aerobic respiration.

As substrate concentration increases, the reaction velocity increases because more enzyme active sites are occupied. Once all active sites are saturated, the reaction reaches its maximum rate (Vmax).

Allosteric regulators bind to regions of the enzyme distinct from the active site, inducing conformational changes that affect enzyme activity. This regulation can either activate or inhibit the enzyme, playing a key role in metabolic control.

Feedback inhibition is a regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme that acts early in the pathway. This helps to prevent the overaccumulation of the product and maintain metabolic balance.

NAD+ is required by dehydrogenase enzymes in the citric acid cycle to accept electrons. Its reduction to NADH is a critical step in transferring energy to subsequent stages of cellular respiration.

During electron transport, complexes in the inner mitochondrial membrane actively pump protons from the matrix to the intermembrane space. This establishes an electrochemical gradient known as the proton motive force, which is vital for ATP synthesis via chemiosmosis.

Upon release into the cytosol, cytochrome c binds with apoptotic protease activating factor-1 (Apaf-1) to form the apoptosome, which then activates caspases. This cascade ultimately leads to the execution of programmed cell death.

In substrate-level phosphorylation, a phosphate group is directly transferred from a phosphorylated substrate to ADP to form ATP. Oxidative phosphorylation, however, uses the energy from a proton gradient established by the electron transport chain to drive ATP synthesis through ATP synthase.

A competitive inhibitor binds to the enzyme's active site, competing with the substrate. This leads to an increase in the apparent Km since a higher substrate concentration is needed to achieve half of Vmax, though the maximum rate (Vmax) remains unchanged.

Complex I is essential for oxidizing NADH and pumping protons into the intermembrane space. A mutation in a key subunit would impair these functions, resulting in a weakened proton gradient and consequently decreased ATP synthesis during oxidative phosphorylation.