Astronomy Chapter 28 Review

The famed meteorite with carbonate rocks and possible microfossils came from:

The first step in cosmic evolution is:

If correct the number of technological civilizations in the galaxy should be equal to:

Of the terrestrial planets, Saturn seems to be most promising to exobiologists.

Why is the hypothesis that life on Earth came from outer space considered plausible?

An extraterrestrial observer would pick up the strongest radio signals when:

Of the billions of possible combinations of atoms into organic molecules, only about 1500 actually occur.

Elliptical galaxies will be more likely to have evolved intelligences than the stars close to the Milky Way.

Taking the total number of stars in the Milky Way and dividing by the age of the Milky Way is a way to estimate:

The water hole is a region around Sun-like stars where liquid water can exist on the surfaces of terrestrial planets

Assuming conditions for life and intelligence in the Galaxy, what factor limits the number of galactic civilizations?

Organic molecules are:

Which of the following appears most favored by natural selection?

Each factor in the Drake Equation has a well-known, established value.

NASA has NOT found definite proof for the past existence of life on Mars

Hundreds of complex organic molecules exist in deep space, especially in the giant molecular clouds

During which step in cosmic evolution did diverse life forms begin to arise?

Large molecules found in meteorites and interstellar clouds is evidence that:

Some scientists believe that silicon-based life is possible because:

Earth behaves as an artificial pulsar, with the strongest pulses for alien observers when NA is either rising or setting

Most SETI searches are done at:

Life emerged on Earth about a billion years after the solar system formed.

How does Drake define a technological civilization?

Of all the chemical elements, the one most crucial to the complexity of life is:

As yet, no human probe has completely left our solar system and gone into interstellar space.

For which of these forms of life is it hardest to apply present criteria for life, based on its behavior when isolated?

What is meant by the "habitable zone"?

What important molecules of life did Miller and Urey brew up?

The last step in cosmic evolution is:

If the material for life were introduced from space after the Earth formed, a major carrier would have been:

During which step in cosmic evolution were the chemical bases for life created?

Comets were likely a major agent in bringing both water and organic molecules to the surface of the early Earth

Which of these does Mars NOT have to help its case of past or present life?