Question 1

Which of the following molecules is not a carrier of electrons in the electron transport system (ETS)?

Accepted Answer

Copper-nickel compounds are not involved in the electron transport system. The other choices listed are all known carriers of electrons in the ETS.

Question 2

Which of the following would not be used as a final electron acceptor in anaerobic respiration?

Accepted Answer

Anaerobic respiration occurs in the absence of oxygen, so oxygen cannot be used as a final electron acceptor in this type of respiration. Instead, other molecules such as sulfur, iron, or nitrogen may serve as the final electron acceptor in various anaerobic respiratory pathways. Protons, on the other hand, are not molecules that can act as electron acceptors, but rather are involved in creating an electrochemical gradient that drives ATP synthesis in both aerobic and anaerobic respiration.

Question 3

The chemiosmotic model of ATP synthesis is based on several lines of experimental evidence.Which of the following statements is not correct experimental evidence to support the chemiosmotic model?

Accepted Answer

This statement is not correct experimental evidence because the chemiosmotic model is based on the requirement of a membrane-enclosed compartment for oxidative phosphorylation to occur. In fact, the model proposes that the proton gradient established across the membrane is essential for driving ATP synthesis. Therefore, the fact that oxidative phosphorylation does not require a membrane-enclosed compartment contradicts the chemiosmotic model rather than supporting it.

Question 4

Of the carrier molecules in the electron transport chain,which has heme as part of its prosthetic group?

Accepted Answer

Cytochromes have heme as part of their prosthetic group. Flavoproteins contain flavin and iron-sulfur proteins contain iron-sulfur clusters, while copper-containing cytochromes have a copper atom in their prosthetic group. Coenzyme Q does not contain heme in its structure.

Question 5

In electron transport,which respiratory complex is not involved in the flow of electrons from NADH?

Accepted Answer

Complex II, also known as succinate dehydrogenase, accepts electrons from FADH2 rather than NADH. Therefore, it is not involved in the flow of electrons from NADH.

Question 6

The form of fatty acid that is transported into the mitochondrion is

Accepted Answer

Fatty acids are transported into the mitochondrion as fatty acyl CoA via the carnitine shuttle system. This process involves the conversion of fatty acids into fatty acyl CoA in the cytosol, and then the transfer of fatty acyl CoA into the mitochondrion with the help of the carnitine shuttle system.

Question 7

Which of the numbered respiratory complexes is not correctly paired with its name?

Accepted Answer

Complex IV is actually known as cytochrome c oxidase, not cytochrome c reductase.

Question 8

The overall efficiency of aerobic respiration in eukaryotes is about

Accepted Answer

The overall efficiency of aerobic respiration in eukaryotes is about 55%, as a significant portion of energy is lost as heat during the process.

Question 9

Pyruvate dehydrogenase is regulated by all of the following except

Accepted Answer

Pyruvate dehydrogenase is regulated by NADH, ATP, AMP, and acetyl CoA, but not directly by CO₂.

Question 10

Crista junctions

Accepted Answer

Crista junctions are narrow openings that limit the movement of molecules between the intracristae space (inside the folds of the inner mitochondrial membrane) and the intermembrane space, helping to maintain distinct environments within the mitochondrion.

Question 11

In electron transport,which respiratory complex is not involved in the flow of electrons from FADH₂?

Accepted Answer

The answer of In electron transport,which respiratory complex is not...

Question 12

Of the following sequences,which shows the correct molecules through which electrons flow when delivered to the electron transport system by NADH?

Accepted Answer

NADH delivers electrons to complex I, which then passes them on to coenzyme Q (ubiquinone). The electrons then move to complex III, which passes them on to cytochrome c before reaching complex IV and then reacting with oxygen. Therefore, the correct sequence is complex I, coenzyme Q, complex III, cytochrome c, complex IV, and oxygen, which is represented by option D.

Question 13

The condition known as ketosis is characterized by

Accepted Answer

The answer of The condition known as ketosis is characterized...

Question 14

The Q cycle

Accepted Answer

The Q cycle allows for the movement of protons between the intermembrane space and the matrix without additional electrons.

Answer: E 
 The Q cycle is not only associated with complex III but also mediates transfer of electrons to oxygen and generates superoxide, making choice E the correct answer.

Question 15

In brown fat,________ present in the inner mitochondrial membrane uncouples ATP synthesis from electron transport in infants and other newborn mammals.

Accepted Answer

Thermogenin, also known as uncoupling protein 1 (UCP1), is present in the inner mitochondrial membrane of brown fat cells and plays a critical role in generating heat through uncoupling of ATP synthesis from electron transport. This process is especially important for infants and other newborn mammals that require heat production to maintain body temperature. Choices B, C, D, and E are not involved in the uncoupling process in brown fat cells.

Question 16

The TCA cycle and glyoxylate cycle are similar in many respects.Which of the following statements accurately describes these cycles?

Accepted Answer

The statement that accurately describes both cycles is that "In the glyoxylate cycle, two acetyl CoA molecules are used to generate succinate." This is because both the TCA cycle and the glyoxylate cycle start with the breakdown of acetyl CoA and utilize a series of reactions to generate energy intermediates. In the TCA cycle, the intermediates are used for further energy production, while in the glyoxylate cycle, they are used for biosynthesis. However, the key difference between the two cycles is that the TCA cycle generates CO2 as a byproduct through a series of decarboxylating reactions, while the glyoxylate cycle has only a single decarboxylation step. Additionally, the glyoxylate cycle is used by some organisms to bypass the decarboxylation steps of the TCA cycle in order to synthesize carbohydrates from acetyl CoA.

Question 17

In prokaryotes,aerobic respiration generates ________ ATP molecules.

Accepted Answer

Aerobic respiration in prokaryotes generates 38 ATP molecules through the complete breakdown of glucose or other organic molecules. This is achieved through glycolysis, the Krebs cycle, and oxidative phosphorylation. Choice A is incorrect because it only represents the ATP produced in glycolysis. Choices B and D are too high and do not accurately reflect the ATP yield of aerobic respiration in prokaryotes. Choice E is incorrect because prokaryotes are capable of aerobic respiration.

Question 18

Multiple protein complexes associated with the cellular respiration are known as

Accepted Answer

The protein complexes associated with cellular respiration are known as respirasomes. These respirasomes contain multiple protein complexes, including complex I, II, III, and IV, that are involved in the electron transport chain and ATP synthesis.

Question 19

Proton gradients are generated by all of the following complexes except

Accepted Answer

Complex II (succinate dehydrogenase) does not pump protons across the inner mitochondrial membrane. It participates in the respiratory chain by passing electrons to coenzyme Q, but does not contribute to proton pumping. On the other hand, Complexes I, III, and IV all pump protons, and coenzyme Q serves as a shuttle for both electrons and protons within the respiratory chain.

Question 20

Of the following electron carriers of the electron transport system,which transfers protons in addition to electrons?

Accepted Answer

Coenzyme Q transfers both protons and electrons during the electron transport system.

Quiz 10: Chemotrophic Energy Metabolism: Aerobic Respiration

Which of the following molecules is not a carrier of electrons in the electron transport system (ETS) ?