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.

answer: angiosperms

dicots

angiosperms are highly evolved plants, they produce seeds which are enclosed within in a carple. these are the largest group of plants on earth. they include trees, shrubs, herbs and small flowering plants. angiosperms exhibit a flowering stage in their life cycle. the flower serves the function of reproduction and fruit formation in majority of angiosperms. dicot is the term used to describe flowering plants that have two seed leaves. dicots are plants which develop seeds which split into two parts called cotyledons. each cotyledon contains one embryo.

here, a small purple flower development indicates that the plant belongs to angiosperms and having two embryonic leaves indicates it belongs to dicots.  

answerall of the above;