A researcher discovers a new unicellular organism that contains a single circular chromosome and no membrane-bound organelles. Upon closer observation, the researcher notices that this organism can also fix nitrogen and produce methane. How should this organism be classified?

The organism is anaerobic bacteria.

Explanation:

Bacteria is a prokaryotic microorganism that have different shapes and can inhabit in different habitat regions.

Bacteria is an important factor in the ecosystem as they have some unique features like they can capable of recycling vitamin B₁₂ and provide it through the food chain.

It play a vital role in nitrogen cycle as they helps to fix nitrogen in the ecosystem which is obtianed by plants and animals for their growth and development.

Methanogenesis is a process of formation of methane in the environment by some microbes like anaerobic bacteria through the process of anaerobic respiration.

i'm pretty sure it's spores

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.