Question

Evolutionary biologists maintain that glycolysis is a metabolic pathway that evolved on earth prior to the divergence of life on planet Earth into different Domains. Which of the following statements best supports this hypothesis?
A. The process of glycolysis, with few molecular modifications, is used by all cells on the planet regardless of the domain to which they belong.
B. Glycolysis is the only metabolic pathway that does not use or require the presence of oxygen.
C. The process of glycolysis is used by all eukaryotic organisms from all domains and kingdoms.
D. The enzymes used in the process of glycolysis are found in the cytosol of cells rather than in a membrane-enclosed organelle.

Answer 1

The metabolic pathway by which one molecule of glucose is converted into two molecules of pyruvate, two hydrogen ions, and two molecules of water is called glycolysis. The high energy molecules of ATP and NADH are synthesized here by the free energy released in the process. It is a sequence of 10 enzyme-catalyzed reactions and its main function is to produce energy in the form of ATP.

Complete Answer:
Let us analyze the options to find the correct answer-
- Option A: This option does not talk about the evolution of the process and why it is used by all the cells. Though this statement states the correct thing this gives an unclear idea about evolution, thus it is incorrect.
- Option B: Glycolysis does not require oxygen and is a common pathway for the formation of energy molecules in both aerobic and anaerobic organisms. Thus possibly, this process would have appeared prior to the divergence of life on planet Earth into different Domains since the early atmosphere lacked oxygen and the aerobic conditions have evolved from the anaerobic one. Therefore, this option seems most appropriate.
- Option C: This statement is incorrect because glycolysis takes place in the cytoplasm of most prokaryotic and all eukaryotic cells. As it does not speak about the prokaryotic organisms, this option is incorrect.
- Option D: Glycolytic enzymes are located on the outside of the mitochondria. But, the location of the glycolytic enzymes speaks nothing about its evolutionary relationships and thus this option is incorrect.

Therefore, the correct option is B. Glycolysis is the only metabolic pathway that does not use or require the presence of oxygen.

Note: Glycolysis was probably one of the earliest metabolic pathways to evolve since it is used by nearly all of the organisms on earth. The first prokaryotes did not have access to a large supply of oxygen in the early Earth atmosphere, so they likely had to use glycolysis to create ATP. Without glycolysis, living organisms would not have the ability to engage in fermentation or begin the process of Cellular Respiration.