Exam 18: Life in the Universe

Scientists have shown that ammonia and methane,mixed together with hydrogen,carbon dioxide,or nitrogen,and exposed to electrical sparks,can produce some of the amino acids essential for life.

Some forms of life on Earth are silicon-based.

Complex microorganisms that have complex DNA enclosed in a cell nucleus are called:

Calculate the maximum likelihood that any technically advanced civilization that arose still exists in our galaxy today.

Which one of the following is NOT one of the six chemical elements commonly found in living organisms?

According to the theory of evolution,chemical reactions resulting in the mutation of a molecule are a natural and inevitable occurrence.

Given the following information,what would be the number of intelligent civilizations in our galaxy? If all stars formed planets; each planet has a 0.1 percent chance of supporting life; every time conditions are right life develops; and only 0.001 percent of the time intelligent life develops surviving indefinitely.

The habitable zone for a 1 M _$\odot$ star ranges from 0.9 to 1.4 AU from the star.

Examine the figure below. The habitable zone around a star depends most on its:

Mutations always lead to improvements in an organism's ability to survive and reproduce.

If the most pessimistic assumptions in the Drake equation were true,we would:

Why was the comet impact a chance happening that benefited the evolution of humans?

Approximately 10 percent of all life on Earth has been in the form of microorganisms.

If the entire history of the Earth were scaled to fit into one day,what time of day would microorganisms first form,oxygen start becoming a significant component of the atmosphere,and humans split off from their genetic ancestors?

Describe the difference between prokaryotes and eukaryotes.

Where do we think life first formed on the Earth?

If you wanted to find intelligent life in the universe,what spectral types of stars would you study and why?

If we model the history of the Earth as a single day,at what time would the first human civilizations appear?

Which one of the following is NOT one of the three categories of terrestrial life based on their DNA characteristics?

SETI's Allen Telescope Array (image below)is designed to search __________ for signs of intelligent life.