Respiration in Plants MCQs

Consider the components of Respiratory Complex I:

I. Complex I is NADH Dehydrogenase complex.
II. It accepts electrons from NADH + H⁺ produced in the mitochondrial matrix.
III. It transfers electrons to Ubiquinone (UQ) located within the inner membrane.
IV. It contains FAD and Cytochrome c oxidase.

Which statements are correct?

Read the following statements about Complex II of the Electron Transport System:

I. It is known as the Succinate Dehydrogenase complex.
II. It accepts reducing equivalents via FADH₂ generated in the TCA cycle.
III. It pumps protons across the inner membrane into the intermembrane space.
IV. It transfers electrons to Ubiquinone (UQ).

Which statement is INCORRECT?

Regarding Cytochrome c in the Electron Transport Chain:

I. It is a small protein attached to the outer surface of the inner mitochondrial membrane.
II. It acts as a mobile electron carrier between Complex III and Complex IV.
III. It contains copper centres Cu_A and Cu_B.
IV. It transfers electrons directly to molecular oxygen.

Which statements are correct?

Consider the components of Complex IV:

I. Known as Cytochrome c oxidase complex.
II. Contains Cytochromes a and a₃.
III. Possesses two copper centers (Cu_A and Cu_B).
IV. Passes electrons directly to O₂, reducing it to H₂O.

Which option contains correct statements?

Statement analysis on ATP yield per coenzyme molecule oxidized in ETS:

I. Oxidation of one molecule of NADH + H⁺ yields 3 molecules of ATP.
II. Oxidation of one molecule of FADH₂ yields 2 molecules of ATP.
III. NADH enters at Complex I while FADH₂ enters at Complex II.
IV. FADH₂ yields more ATP than NADH because it enters earlier in ETS.

Which statements are correct?

Consider the structure and function of ATP Synthase (Complex V):

I. F₁ headpiece is a peripheral membrane protein containing the catalytic site for ATP synthesis.
II. F₀ is an integral membrane protein complex forming a proton channel.
III. Protons pass through F₀ from intermembrane space to matrix down the electrochemical gradient.
IV. For each ATP produced, 4H⁺ pass through F₀.

Which statements are correct?

Regarding the terminal role of Oxygen in aerobic respiration:

I. Oxygen acts as the final hydrogen/electron acceptor at the end of ETS.
II. Oxygen is reduced to form water (H₂O).
III. Oxygen role is limited to the terminal stage, yet it drives the entire process.
IV. Oxygen pumps protons actively into the matrix.

Which statements are correct?

Compare photophosphorylation and oxidative phosphorylation:

I. Photophosphorylation uses light energy to create a proton gradient.
II. Oxidative phosphorylation uses energy of oxidation-reduction reactions.
III. Both processes require membrane-bound ATP synthase and a proton gradient.
IV. Oxidative phosphorylation occurs on thylakoid membranes of chloroplasts.

Which statements are correct?

Consider Ubiquinone (UQ/Ubiquinol) in ETS:

I. Ubiquinone is located within the inner mitochondrial membrane.
II. Receives reducing equivalents from Complex I (NADH).
III. Receives reducing equivalents from Complex II (FADH₂).
IV. Transfers electrons to Complex III, which then passes them to Cytochrome c.

Which statements are correct?

Read the following statements on Complex III of ETS:

I. Known as Cytochrome bc₁ complex.
II. Contains Cytochrome b, Fe-S center, and Cytochrome c₁.
III. Receives electrons from reduced ubiquinone (ubiquinol).
IV. Passes electrons directly to molecular oxygen.

Which statement is INCORRECT?