Question

Which of these is the chief reason the protocell was probably a fermenter? a. The protocell didn't have any enzymes. b. The atmosphere didn't have any oxygen. c. Fermentation provides the most energy. d. There was no ATP yet. e. All of these are correct.

Short answer

The chief reason the protocell was probably a fermenter is b. The atmosphere didn't have any oxygen.

Step-by-step solution

Understanding fermentation

Fermentation is an anaerobic process in which energy is produced from organic compounds without the involvement of oxygen. This process typically occurs in microorganisms such as yeast and bacteria and provides them with energy in the absence of oxygen.

Evaluating the given reasons

We will now assess each given reason and determine its relevance to the protocell being a fermenter: a. The protocell didn't have any enzymes: Enzymes are protein molecules that accelerate chemical reactions, including those involved in energy production. Although the protocell might have lacked specific enzymes, this reason doesn't explain why it would have been a fermenter. b. The atmosphere didn't have any oxygen: Since fermentation is an anaerobic process, the absence of oxygen would favor this type of energy production over other methods that rely on oxygen, such as cellular respiration. This reason appears to be relevant to the protocell being a fermenter. c. Fermentation provides the most energy: This statement is incorrect as aerobic respiration, which requires oxygen, provides more energy than fermentation. d. There was no ATP yet: ATP (adenosine triphosphate) is a molecule that provides energy for cellular processes. Although the protocell might not have had ATP molecules, it doesn't necessarily mean that it was a fermenter, as there are various ways to produce energy. e. All of these are correct: Since reason c is incorrect and others aren't clear reasons for the protocell being a fermenter, this choice cannot be the correct answer.

Determine the chief reason

Based on our evaluation of the given reasons, the absence of oxygen in the atmosphere (reason b) is the most plausible explanation for the protocell being a fermenter. In an anaerobic environment, fermentation is favored over other energy production methods that require oxygen. Thus, the chief reason the protocell was probably a fermenter is: b. The atmosphere didn't have any oxygen.