Which of these statements best explains the origin of life on Earth?
Select one:
a. Primitive plants were created from living molecules.
b. Plant cells were formed by the destruction of fossils in rocks.
c. Non-living molecules were transformed into bacteria by chemical processes.
d. Reproducing molecules evolved into living molecules by biological processes.

Question

Which of these statements best explains the origin of life on Earth? 
Select one:
a. Primitive plants were created from living molecules. 
b. Plant cells were formed by the destruction of fossils in rocks. 
c. Non-living molecules were transformed into bacteria by chemical processes. 
d. Reproducing molecules evolved into living molecules by biological processes.

anonymous · Answer

The krebs cycle is an aerobic process and is part of glucose catabolism. Key thing to noete is that this happens IN THE MITOCHONDRIA. The molecule that enters the krebs cycle is acetyl coA. This is a 2 carbon derivative of pyruvate from the glycolytic cycle which combines with oxaloacetate to make a 6 carbon molecule. The cycle is a series of Oxidation-reduction reactions which regenerates the starting material oxaloacetate so the cycle can contineu. The main goal of the krebs cycle as I was taught in Biochem is to create an abundance of NADH electron carrier molecules for use in the Electron Transport chain, aka oxidative phosphorylation. FADH is also generated but that cannot generate as many ATP as NADH can. The products of this cycle are CO2, NADH, FADH, and an ATP via GTP formation. 

 To answer your question there are electron carrying molecules created in this cycle which will be transported to the ETC (electron transport chain) to maintain the gradient that allows ATP to be made in large quantities. I hope this is in depth enough for you.

anonymous · Answer

C. Most prebiotic molecules that may have become part of life were protected from destruction by the sun's high-energy UV radiation.