Question

multiple choice question
according to our current understanding, how did cellular respiration evolve?
o cellular respiration appeared when two organisms merged, combining their metabolic activities.
o all of the steps in cellular respiration appeared simultaneously in an ancestral organism.
o cellular respiration first appeared as a very long process, and has since been simplified down to the few steps that extract energy most efficiently.
o the different steps in cellular respiration evolved over time.

Explanation:

Cellular respiration is a complex process. It is believed that its different steps evolved over time through natural - selection and the development of metabolic pathways in organisms. The idea of it appearing all at once or through a simple merger of organisms is not consistent with current understanding. Also, it did not start as a long - process and then simplify; rather, it built up complexity over evolutionary time.

Answer:

The different steps in cellular respiration evolved over time.