Question

Astrobiologists searching for signs of life on other planets primarily search for __________.

Answer 1

Primarily search for microorganisms.
Astrobiologists study the origin, evolution, distribution and future of life in the Universe. These studies include both extraterrestrial and terrestrial life. There are several reasons why when searching for extraterrestrial life, astrobiologists mainly focus on microorganisms. This is because life on Earth has evolved from microorganisms and microbes have significantly influenced the development of Earth's environment. Also, microbes are very resistant, versatile and adaptive organisms, capable of surviving in harsh and seemingly unhabitable environments.

Answer 2

Water. This is due to the fact that chemical reactions necessary for life require a solvent for them to occur spontaneously. Water is, according to astrophysicists, the most abundant solvent in the universe and retains its liquid phase even at higher temperatures compared to other solvents. Water, also, is a polar solvent that will dissolve most elements necessary for biochemical reactions.