Determine whether each of these statements is true or false

Determine whether each of these statements is true or false and then explain why?

a) Respiration is impossible without oxygen as an electron acceptor for the reoxidation of coenzymes.

b) The most important contribution of the citric acid cycle to energy metabolism is the extraction of high-energy electrons during the oxidation of acetyl CoA to CO2.

c) Each respiratory enzyme complex in the electron-transport chain has a greater affinity for electrons than its predecessors, so that electrons pass sequentially from one complex to another until they are finally transferred to oxygen, which has the greatest electron affinity of all.

d) ER-bound nad free ribosomes, which are structurally and functionally identical, differ only in the proteins they happen to be making at a particular time.

Solution

Answer:

a). False

Respiration is an aerobic process in many organisms as oxygen is the single most common electron acceptor for reoxidation for reduced coenzymes. The other electron acceptors such as S, H+, or Fe3+ can be used in the absence of oxygen (anaerobic respiration).

b). True

c). True

d). True

Ribosomes translate mRNAs in the cytosol. The mRNAs for certain proteins encode a signal sequence for the ER membrane. After this sequence has been synthesized, it directs the nascent protein, along with the ribosome and the mRNA, to the ER membrane. Ribosomes translating mRNAs that do not encode such a sequence remain free in the cytosol.