Question

question 56
2 pts
the oxygen revolution changed earths environment dramatically. which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
the persistence of some animal groups in anaerobic habitats
the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria

Explanation:

Analyze the impact of the oxygen revolution

The oxygen revolution (Great Oxidation Event) introduced abundant free oxygen (\(\text{O}_2\)) into Earth's oceans and atmosphere. This environmental shift was toxic to many anaerobic organisms but opened up a highly efficient metabolic pathway for others.

Evaluate the metabolic advantages of free oxygen

Organisms that evolved aerobic cellular respiration could use oxygen as a terminal electron acceptor. This allowed them to harvest significantly more energy (ATP) from organic molecules compared to anaerobic pathways.

Assess the given multiple-choice options

• Option 1: Directly describes the evolution of cellular respiration utilizing oxygen to harvest energy, which is the primary metabolic advantage of the oxygen revolution.
• Option 2: Persistence in anaerobic habitats is a survival strategy to avoid oxygen, not an adaptation taking advantage of its presence.
• Option 3: Protective pigments are a defense mechanism against oxygen toxicity, not a way to actively utilize or take advantage of it.
• Option 4: The endosymbiosis of cyanobacteria led to chloroplasts, which produce oxygen rather than taking advantage of its pre-existing environmental presence.

Answer:

• the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules (Correct answer)
• the persistence of some animal groups in anaerobic habitats
• the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
• the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria