AP BIOLOGY

CELL RESPIRATION

THE KREBS CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The energy in the electrons donated from NADH and FADH2 is used to:
A
Actively transport H+ ions from the matrix to the intermembrane space
B
Actively transport H+ ions from the matrix to the cytoplasm
C
Actively transport H+ ions from the intermembrane space to the matrix
D
Actively transport H+ ions from the cytoplasm to the intermembrane space
Explanation: 

Detailed explanation-1: -Summary. Electron transport is the final stage of aerobic respiration. In this stage, energy from NADH and FADH2 is transferred to ATP. During electron transport, energy is used to pump hydrogen ions across the mitochondrial inner membrane, from the matrix into the intermembrane space.

Detailed explanation-2: -During oxidative phosphorylation, electrons derived from NADH and FADH2 combine with O2, and the energy released from these oxidation/ reduction reactions is used to drive the synthesis of ATP from ADP.

Detailed explanation-3: -NADH and FADH2 carry high-energy electrons to the electron transport chain in cellular respiration. NADPH carries high-energy electrons to the electron transport chain in photosynthesis.

Detailed explanation-4: -The process of forming ATP from the electron transport chain is known as oxidative phosphorylation. Electrons carried by NADH + H+ and FADH2 are transferred to oxygen via a series of electron carriers, and ATPs are formed. Three ATPs are formed from each NADH + H+, and two ATPs are formed for each FADH2 in eukaryotes.

Detailed explanation-5: -Explanation: Both NADH and FADH2 donate two electrons to the electron transport chain, so theoretically they should make the same amount of ATP. However, NADH donates its electrons to complex I while FADH2 donates its electrons further “downstream” at complex II.

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